diff --git a/locale/ID.po b/locale/ID.po
index ba2662201f..0626f461e8 100644
--- a/locale/ID.po
+++ b/locale/ID.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -372,6 +372,10 @@ msgstr "Bit clock dan word harus memiliki kesamaan pada clock unit"
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Kedua pin harus mendukung hardware interrut"
@@ -812,7 +816,7 @@ msgstr ""
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -891,11 +895,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Frekuensi PWM tidak valid"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -971,7 +975,8 @@ msgstr "Pin untuk channel kanan tidak valid"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Pin-pin tidak valid"
 
@@ -1430,7 +1435,7 @@ msgstr ""
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3111,8 +3116,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx dan rx keduanya tidak boleh kosong"
diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index 4201850311..8ab26e4977 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -368,6 +368,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr ""
@@ -801,7 +805,7 @@ msgstr ""
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -880,11 +884,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -960,7 +964,8 @@ msgstr ""
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr ""
 
@@ -1414,7 +1419,7 @@ msgstr ""
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3085,8 +3090,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr ""
diff --git a/locale/cs.po b/locale/cs.po
index 8160156995..3663933703 100644
--- a/locale/cs.po
+++ b/locale/cs.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -368,6 +368,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr ""
@@ -801,7 +805,7 @@ msgstr ""
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -880,11 +884,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -960,7 +964,8 @@ msgstr ""
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr ""
 
@@ -1414,7 +1419,7 @@ msgstr ""
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3085,8 +3090,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr ""
diff --git a/locale/de_DE.po b/locale/de_DE.po
index fe738d62a3..9e4bd36c08 100644
--- a/locale/de_DE.po
+++ b/locale/de_DE.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2020-05-18 02:48+0000\n"
 "Last-Translator: Jeff Epler <jepler@gmail.com>\n"
 "Language-Team: German <https://later.unpythonic.net/projects/circuitpython/"
@@ -379,6 +379,10 @@ msgstr "Bit clock und word select müssen eine clock unit teilen"
 msgid "Bit depth must be multiple of 8."
 msgstr "Bit depth muss ein Vielfaches von 8 sein."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Beide pins müssen Hardware Interrupts unterstützen"
@@ -814,7 +818,7 @@ msgstr "Gruppe voll"
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -895,11 +899,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Ungültige PWM Frequenz"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -975,7 +979,8 @@ msgstr "Ungültiger Pin für rechten Kanal"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Ungültige Pins"
 
@@ -1438,7 +1443,7 @@ msgstr "Die Stackgröße sollte mindestens 256 sein"
 msgid "Stream missing readinto() or write() method."
 msgstr "Stream fehlt readinto() oder write() Methode."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3133,8 +3138,7 @@ msgstr "tupel/list hat falsche Länge"
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx und rx können nicht beide None sein"
diff --git a/locale/en_US.po b/locale/en_US.po
index 638e70f66a..5ef3da275d 100644
--- a/locale/en_US.po
+++ b/locale/en_US.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2018-07-27 11:55-0700\n"
 "Last-Translator: \n"
 "Language-Team: \n"
@@ -368,6 +368,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr ""
@@ -801,7 +805,7 @@ msgstr ""
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -880,11 +884,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -960,7 +964,8 @@ msgstr ""
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr ""
 
@@ -1414,7 +1419,7 @@ msgstr ""
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3085,8 +3090,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr ""
diff --git a/locale/en_x_pirate.po b/locale/en_x_pirate.po
index fa94bfa1fa..f131144aec 100644
--- a/locale/en_x_pirate.po
+++ b/locale/en_x_pirate.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2020-03-30 22:11+0000\n"
 "Last-Translator: Tannewt <devnull@unpythonic.net>\n"
 "Language-Team: English <https://later.unpythonic.net/projects/circuitpython/"
@@ -377,6 +377,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr ""
@@ -810,7 +814,7 @@ msgstr ""
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -889,11 +893,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -969,7 +973,8 @@ msgstr "Belay that! Invalid pin for starboard-side channel"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr ""
 
@@ -1423,7 +1428,7 @@ msgstr ""
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3094,8 +3099,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr ""
diff --git a/locale/es.po b/locale/es.po
index a2dcdbd113..5aeb17d451 100644
--- a/locale/es.po
+++ b/locale/es.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2020-05-17 20:56+0000\n"
 "Last-Translator: Jeff Epler <jepler@gmail.com>\n"
 "Language-Team: \n"
@@ -375,6 +375,10 @@ msgstr "Bit clock y word select deben compartir una unidad de reloj"
 msgid "Bit depth must be multiple of 8."
 msgstr "Bits depth debe ser múltiplo de 8."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Ambos pines deben soportar interrupciones por hardware"
@@ -808,7 +812,7 @@ msgstr "Group lleno"
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -889,11 +893,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Frecuencia PWM inválida"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -969,7 +973,8 @@ msgstr "Pin inválido para canal derecho"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "pines inválidos"
 
@@ -1432,7 +1437,7 @@ msgstr "El tamaño de la pila debe ser de al menos 256"
 msgid "Stream missing readinto() or write() method."
 msgstr "A Stream le falta el método readinto() o write()."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3128,8 +3133,7 @@ msgstr "tupla/lista tiene una longitud incorrecta"
 msgid "tuple/list required on RHS"
 msgstr "tuple/lista se require en RHS"
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "Ambos tx y rx no pueden ser None"
diff --git a/locale/fil.po b/locale/fil.po
index 3593fa7e94..551b57a05b 100644
--- a/locale/fil.po
+++ b/locale/fil.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2018-12-20 22:15-0800\n"
 "Last-Translator: Timothy <me@timothygarcia.ca>\n"
 "Language-Team: fil\n"
@@ -374,6 +374,10 @@ msgstr "Ang bit clock at word select dapat makibahagi sa isang clock unit"
 msgid "Bit depth must be multiple of 8."
 msgstr "Bit depth ay dapat multiple ng 8."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Ang parehong mga pin ay dapat na sumusuporta sa hardware interrupts"
@@ -815,7 +819,7 @@ msgstr "Puno ang group"
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -896,11 +900,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Mali ang PWM frequency"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -976,7 +980,8 @@ msgstr "Mali ang pin para sa kanang channel"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Mali ang pins"
 
@@ -1437,7 +1442,7 @@ msgstr "Ang laki ng stack ay dapat na hindi bababa sa 256"
 msgid "Stream missing readinto() or write() method."
 msgstr "Stream kulang ng readinto() o write() method."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3141,8 +3146,7 @@ msgstr "mali ang haba ng tuple/list"
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx at rx hindi pwedeng parehas na None"
diff --git a/locale/fr.po b/locale/fr.po
index c9b5bf74af..30016104cb 100644
--- a/locale/fr.po
+++ b/locale/fr.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: 0.1\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2020-05-26 19:37+0000\n"
 "Last-Translator: Jeff Epler <jepler@gmail.com>\n"
 "Language-Team: French <https://later.unpythonic.net/projects/circuitpython/"
@@ -386,6 +386,10 @@ msgstr "'bit clock' et 'word select' doivent partager une horloge"
 msgid "Bit depth must be multiple of 8."
 msgstr "La profondeur de bit doit être un multiple de 8."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Les deux entrées doivent supporter les interruptions matérielles"
@@ -830,7 +834,7 @@ msgstr "Groupe plein"
 msgid "Hardware busy, try alternative pins"
 msgstr "Matériel occupé, essayez d'autres broches"
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr "Matériel utilisé, essayez d'autres broches"
 
@@ -911,11 +915,11 @@ msgstr "Sélection de broches I2C non valide"
 msgid "Invalid PWM frequency"
 msgstr "Fréquence de PWM invalide"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr "Sélection de broches SPI non valide"
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr "Sélection de broches UART non valide"
 
@@ -991,7 +995,8 @@ msgstr "Broche invalide pour le canal droit"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Broches invalides"
 
@@ -1458,7 +1463,7 @@ msgstr "La pile doit être au moins de 256"
 msgid "Stream missing readinto() or write() method."
 msgstr "Il manque une méthode readinto() ou write() au flux."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr "Fournissez au moins une broche UART"
 
@@ -3181,8 +3186,7 @@ msgstr "tuple/liste a une mauvaise longueur"
 msgid "tuple/list required on RHS"
 msgstr "tuple ou liste requis en partie droite"
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx et rx ne peuvent être 'None' tous les deux"
diff --git a/locale/it_IT.po b/locale/it_IT.po
index 5a4e3ac5a5..d4d2fadbea 100644
--- a/locale/it_IT.po
+++ b/locale/it_IT.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2018-10-02 16:27+0200\n"
 "Last-Translator: Enrico Paganin <enrico.paganin@mail.com>\n"
 "Language-Team: \n"
@@ -374,6 +374,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr "La profondità di bit deve essere multipla di 8."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Entrambi i pin devono supportare gli interrupt hardware"
@@ -815,7 +819,7 @@ msgstr "Gruppo pieno"
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -896,11 +900,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Frequenza PWM non valida"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -978,7 +982,8 @@ msgstr "Pin non valido per il canale destro"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Pin non validi"
 
@@ -1448,7 +1453,7 @@ msgstr "La dimensione dello stack deve essere almeno 256"
 msgid "Stream missing readinto() or write() method."
 msgstr "Metodi mancanti readinto() o write() allo stream."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3148,8 +3153,7 @@ msgstr "tupla/lista ha la lunghezza sbagliata"
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx e rx non possono essere entrambi None"
diff --git a/locale/ko.po b/locale/ko.po
index 29f825397b..cbbeccc82d 100644
--- a/locale/ko.po
+++ b/locale/ko.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2019-05-06 14:22-0700\n"
 "Last-Translator: \n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -372,6 +372,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr ""
@@ -805,7 +809,7 @@ msgstr ""
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -884,11 +888,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -964,7 +968,8 @@ msgstr "오른쪽 채널 핀이 잘못되었습니다"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "핀이 유효하지 않습니다"
 
@@ -1418,7 +1423,7 @@ msgstr ""
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3090,8 +3095,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr ""
diff --git a/locale/nl.po b/locale/nl.po
index d1477d83dd..f14f449d4d 100644
--- a/locale/nl.po
+++ b/locale/nl.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2020-05-19 17:08+0000\n"
 "Last-Translator: Dustin Watts <dustin_watts@yahoo.com>\n"
 "Language-Team: none\n"
@@ -378,6 +378,10 @@ msgstr "Bit clock en word select moeten een clock eenheid delen"
 msgid "Bit depth must be multiple of 8."
 msgstr "Bit diepte moet een meervoud van 8 zijn."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Beide pinnen moeten hardware interrupts ondersteunen"
@@ -819,7 +823,7 @@ msgstr "Groep is vol"
 msgid "Hardware busy, try alternative pins"
 msgstr "Hardware bezig, probeer alternatieve pinnen"
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr "Hardware in gebruik, probeer alternatieve pinnen"
 
@@ -900,11 +904,11 @@ msgstr "Ongeldige I2C pin selectie"
 msgid "Invalid PWM frequency"
 msgstr "Ongeldige PWM frequentie"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr "Ongeldige SPI pin selectie"
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr "Ongeldige UART pin selectie"
 
@@ -980,7 +984,8 @@ msgstr "Ongeldige pin voor rechter kanaal"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Ongeldige pinnen"
 
@@ -1448,7 +1453,7 @@ msgstr "Stack grootte moet op zijn minst 256 zijn"
 msgid "Stream missing readinto() or write() method."
 msgstr "Stream mist readinto() of write() methode."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr "Geef op zijn minst 1 UART pin op"
 
@@ -3134,8 +3139,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr ""
diff --git a/locale/pl.po b/locale/pl.po
index a5064d6bdf..e8c3c04e88 100644
--- a/locale/pl.po
+++ b/locale/pl.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2019-03-19 18:37-0700\n"
 "Last-Translator: Radomir Dopieralski <circuitpython@sheep.art.pl>\n"
 "Language-Team: pl\n"
@@ -371,6 +371,10 @@ msgstr "Zegar bitowy i wybór słowa muszą współdzielić jednostkę zegara"
 msgid "Bit depth must be multiple of 8."
 msgstr "Głębia musi być wielokrotnością 8."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Obie nóżki muszą wspierać przerwania sprzętowe"
@@ -804,7 +808,7 @@ msgstr "Grupa pełna"
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -885,11 +889,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Zła częstotliwość PWM"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -965,7 +969,8 @@ msgstr "Zła nóżka dla prawego kanału"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Złe nóżki"
 
@@ -1419,7 +1424,7 @@ msgstr "Stos musi mieć co najmniej 256 bajtów"
 msgid "Stream missing readinto() or write() method."
 msgstr "Strumień nie ma metod readinto() lub write()."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3096,8 +3101,7 @@ msgstr "krotka/lista ma złą długość"
 msgid "tuple/list required on RHS"
 msgstr "wymagana krotka/lista po prawej stronie"
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx i rx nie mogą być oba None"
diff --git a/locale/pt_BR.po b/locale/pt_BR.po
index d0d81bccba..8045ed9bac 100644
--- a/locale/pt_BR.po
+++ b/locale/pt_BR.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2018-10-02 21:14-0000\n"
 "Last-Translator: \n"
 "Language-Team: \n"
@@ -371,6 +371,10 @@ msgstr ""
 msgid "Bit depth must be multiple of 8."
 msgstr ""
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Ambos os pinos devem suportar interrupções de hardware"
@@ -810,7 +814,7 @@ msgstr "Grupo cheio"
 msgid "Hardware busy, try alternative pins"
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr ""
 
@@ -889,11 +893,11 @@ msgstr ""
 msgid "Invalid PWM frequency"
 msgstr "Frequência PWM inválida"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr ""
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr ""
 
@@ -971,7 +975,8 @@ msgstr "Pino inválido para canal direito"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Pinos inválidos"
 
@@ -1431,7 +1436,7 @@ msgstr "O tamanho da pilha deve ser pelo menos 256"
 msgid "Stream missing readinto() or write() method."
 msgstr ""
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr ""
 
@@ -3109,8 +3114,7 @@ msgstr ""
 msgid "tuple/list required on RHS"
 msgstr ""
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "TX e RX não podem ser ambos"
diff --git a/locale/sv.po b/locale/sv.po
index 25f8f34da6..803d9a0c67 100644
--- a/locale/sv.po
+++ b/locale/sv.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2020-05-20 18:32+0000\n"
 "Last-Translator: Jonny Bergdahl <jonny@bergdahl.it>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -378,6 +378,10 @@ msgstr "Bitklocka och ordval måste dela en klockenhet"
 msgid "Bit depth must be multiple of 8."
 msgstr "Bitdjupet måste vara multipel av 8."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Båda pinnarna måste stödja maskinvaruavbrott"
@@ -818,7 +822,7 @@ msgstr "Gruppen är full"
 msgid "Hardware busy, try alternative pins"
 msgstr "Hårdvaran är upptagen, prova alternativa pinnar"
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr "Hårdvaran används redan, prova alternativa pinnar"
 
@@ -899,11 +903,11 @@ msgstr "Ogiltigt val av I2C-pinne"
 msgid "Invalid PWM frequency"
 msgstr "Ogiltig PWM-frekvens"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr "Ogiltigt val av SPI-pinne"
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr "Ogiltigt val av UART-pinne"
 
@@ -979,7 +983,8 @@ msgstr "Ogiltig pinne för höger kanal"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Ogiltiga pinnar"
 
@@ -1445,7 +1450,7 @@ msgstr "Stackstorleken måste vara minst 256"
 msgid "Stream missing readinto() or write() method."
 msgstr "Stream saknar readinto() eller write() metod."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr "Ange minst en UART-pinne"
 
@@ -3142,8 +3147,7 @@ msgstr "tupel/lista har fel längd"
 msgid "tuple/list required on RHS"
 msgstr "tupel/lista krävs för RHS"
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx och rx kan inte båda vara None"
diff --git a/locale/zh_Latn_pinyin.po b/locale/zh_Latn_pinyin.po
index 19b79f2c53..3f61b77881 100644
--- a/locale/zh_Latn_pinyin.po
+++ b/locale/zh_Latn_pinyin.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: circuitpython-cn\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-27 11:28+0800\n"
+"POT-Creation-Date: 2020-05-27 10:46-0700\n"
 "PO-Revision-Date: 2019-04-13 10:10-0700\n"
 "Last-Translator: hexthat\n"
 "Language-Team: Chinese Hanyu Pinyin\n"
@@ -377,6 +377,10 @@ msgstr "Bǐtè shízhōng hé dānzì xuǎnzé bìxū gòngxiǎng shízhōng dā
 msgid "Bit depth must be multiple of 8."
 msgstr "Bǐtè shēndù bìxū shì 8 bèi yǐshàng."
 
+#: ports/mimxrt10xx/common-hal/busio/UART.c
+msgid "Both RX and TX required for flow control"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
 msgid "Both pins must support hardware interrupts"
 msgstr "Liǎng gè yǐn jiǎo dōu bìxū zhīchí yìngjiàn zhōngduàn"
@@ -812,7 +816,7 @@ msgstr "Fēnzǔ yǐ mǎn"
 msgid "Hardware busy, try alternative pins"
 msgstr "Yìngjiàn máng, qǐng chángshì qítā zhēnjiǎo"
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Hardware in use, try alternative pins"
 msgstr "Shǐyòng de yìngjiàn, qǐng chángshì qítā yǐn jiǎo"
 
@@ -893,11 +897,11 @@ msgstr "Wúxiào de I2C yǐn jiǎo xuǎnzé"
 msgid "Invalid PWM frequency"
 msgstr "Wúxiào de PWM pínlǜ"
 
-#: ports/mimxrt10xx/common-hal/busio/SPI.c ports/stm/common-hal/busio/SPI.c
+#: ports/stm/common-hal/busio/SPI.c
 msgid "Invalid SPI pin selection"
 msgstr "Wúxiào de SPI yǐn jiǎo xuǎnzé"
 
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
+#: ports/stm/common-hal/busio/UART.c
 msgid "Invalid UART pin selection"
 msgstr "Wúxiào de UART yǐn jiǎo xuǎnzé"
 
@@ -973,7 +977,8 @@ msgstr "Yòuxián tōngdào yǐn jiǎo wúxiào"
 #: ports/atmel-samd/common-hal/busio/UART.c
 #: ports/atmel-samd/common-hal/i2cslave/I2CSlave.c
 #: ports/cxd56/common-hal/busio/I2C.c ports/cxd56/common-hal/busio/SPI.c
-#: ports/cxd56/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
+#: ports/cxd56/common-hal/busio/UART.c ports/mimxrt10xx/common-hal/busio/SPI.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/I2C.c
 msgid "Invalid pins"
 msgstr "Wúxiào de yǐn jiǎo"
 
@@ -1433,7 +1438,7 @@ msgstr "Duīzhàn dàxiǎo bìxū zhìshǎo 256"
 msgid "Stream missing readinto() or write() method."
 msgstr "Liú quēshǎo readinto() huò write() fāngfǎ."
 
-#: ports/stm/common-hal/busio/UART.c
+#: ports/mimxrt10xx/common-hal/busio/UART.c ports/stm/common-hal/busio/UART.c
 msgid "Supply at least one UART pin"
 msgstr "Dìngyì zhìshǎo yīgè UART yǐn jiǎo"
 
@@ -3126,8 +3131,7 @@ msgstr "yuán zǔ/lièbiǎo chángdù cuòwù"
 msgid "tuple/list required on RHS"
 msgstr "RHS yāoqiú de yuán zǔ/lièbiǎo"
 
-#: ports/atmel-samd/common-hal/busio/UART.c
-#: ports/mimxrt10xx/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
+#: ports/atmel-samd/common-hal/busio/UART.c ports/nrf/common-hal/busio/UART.c
 #: shared-bindings/busio/UART.c
 msgid "tx and rx cannot both be None"
 msgstr "tx hé rx bùnéng dōu shì wú"
diff --git a/ports/mimxrt10xx/common-hal/busio/I2C.c b/ports/mimxrt10xx/common-hal/busio/I2C.c
index 0bb7dcc6c6..cad0fef982 100644
--- a/ports/mimxrt10xx/common-hal/busio/I2C.c
+++ b/ports/mimxrt10xx/common-hal/busio/I2C.c
@@ -81,7 +81,7 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     }
 
     if(self->sda_pin == NULL || self->scl_pin == NULL) {
-        mp_raise_RuntimeError(translate("Invalid I2C pin selection"));
+        mp_raise_ValueError(translate("Invalid I2C pin selection"));
     } else {
         self->i2c = mcu_i2c_banks[self->sda_pin->bank_idx - 1];
     }
diff --git a/ports/mimxrt10xx/common-hal/busio/SPI.c b/ports/mimxrt10xx/common-hal/busio/SPI.c
index 15c320140a..cede7b5bdb 100644
--- a/ports/mimxrt10xx/common-hal/busio/SPI.c
+++ b/ports/mimxrt10xx/common-hal/busio/SPI.c
@@ -91,10 +91,10 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                         || (mcu_spi_sck_list[i].bank_idx != mcu_spi_miso_list[k].bank_idx)) {
                         continue;
                     }
-                    //keep looking if the SPI is taken, edge case
+                    // if SPI is taken, break (pins never have >1 periph)
                     if (reserved_spi[mcu_spi_sck_list[i].bank_idx - 1]) {
                         spi_taken = true;
-                        continue;
+                        break;
                     }
                     //store pins if not
                     self->clock = &mcu_spi_sck_list[i];
@@ -102,11 +102,11 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                     self->miso = &mcu_spi_miso_list[k];
                     break;
                 }
-                if (self->clock != NULL) {
+                if (self->clock != NULL || spi_taken) {
                     break; // Multi-level break to pick lowest peripheral
                 }
             }
-            if (self->clock != NULL) {
+            if (self->clock != NULL || spi_taken) {
                 break;
             }
         // if just MISO, reduce search
@@ -118,14 +118,13 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                 }
                 if (reserved_spi[mcu_spi_sck_list[i].bank_idx - 1]) {
                     spi_taken = true;
-                    continue;
+                    break;
                 }
                 self->clock = &mcu_spi_sck_list[i];
-                self->mosi = NULL;
                 self->miso = &mcu_spi_miso_list[j];
                 break;
             }
-            if (self->clock != NULL) {
+            if (self->clock != NULL || spi_taken) {
                 break;
             }
         // if just MOSI, reduce search
@@ -137,14 +136,13 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                 }
                 if (reserved_spi[mcu_spi_sck_list[i].bank_idx - 1]) {
                     spi_taken = true;
-                    continue;
+                    break;
                 }
                 self->clock = &mcu_spi_sck_list[i];
                 self->mosi = &mcu_spi_mosi_list[j];
-                self->miso = NULL;
                 break;
             }
-            if (self->clock != NULL) {
+            if (self->clock != NULL || spi_taken) {
                 break;
             }
         } else {
@@ -159,7 +157,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
         if (spi_taken) {
             mp_raise_ValueError(translate("Hardware busy, try alternative pins"));
         } else {
-            mp_raise_ValueError(translate("Invalid SPI pin selection"));
+            mp_raise_ValueError(translate("Invalid pins"));
         }
     }
 
diff --git a/ports/mimxrt10xx/common-hal/busio/UART.c b/ports/mimxrt10xx/common-hal/busio/UART.c
index fbb45eeea4..2bec667eb7 100644
--- a/ports/mimxrt10xx/common-hal/busio/UART.c
+++ b/ports/mimxrt10xx/common-hal/busio/UART.c
@@ -39,7 +39,9 @@
 
 #include "fsl_lpuart.h"
 
-// TODO
+//arrays use 0 based numbering: UART1 is stored at index 0
+#define MAX_UART 8
+STATIC bool reserved_uart[MAX_UART];
 
 #define UART_CLOCK_FREQ (CLOCK_GetPllFreq(kCLOCK_PllUsb1) / 6U) / (CLOCK_GetDiv(kCLOCK_UartDiv) + 1U)
 
@@ -79,109 +81,159 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         mp_float_t timeout, uint16_t receiver_buffer_size, byte* receiver_buffer,
         bool sigint_enabled) {
 
-    // TODO: Allow none rx or tx
-
-    bool have_tx = tx != NULL;
-    bool have_rx = rx != NULL;
-    if (!have_tx && !have_rx) {
-        mp_raise_ValueError(translate("tx and rx cannot both be None"));
-    }
-
     self->baudrate = baudrate;
     self->character_bits = bits;
     self->timeout_ms = timeout * 1000;
 
-    const uint32_t rx_count = sizeof(mcu_uart_rx_list) / sizeof(mcu_periph_obj_t);
-    const uint32_t tx_count = sizeof(mcu_uart_tx_list) / sizeof(mcu_periph_obj_t);
+    // We are transmitting one direction if one pin is NULL and the other isn't.
+    bool is_onedirection = (rx != NULL) != (tx != NULL);
+    bool uart_taken = false;
 
-    for (uint32_t i = 0; i < rx_count; ++i) {
-        if (mcu_uart_rx_list[i].pin != rx)
-            continue;
+    const uint32_t rx_count = MP_ARRAY_SIZE(mcu_uart_rx_list);
+    const uint32_t tx_count = MP_ARRAY_SIZE(mcu_uart_tx_list);
 
-        for (uint32_t j = 0; j < tx_count; ++j) {
-            if (mcu_uart_tx_list[j].pin != tx)
+    // RX loop handles rx only, or both rx and tx
+    if (rx != NULL) {
+        for (uint32_t i = 0; i < rx_count; ++i) {
+            if (mcu_uart_rx_list[i].pin != rx) {
                 continue;
-
-            if (mcu_uart_tx_list[j].bank_idx != mcu_uart_rx_list[i].bank_idx)
+            }
+            // If TX is on, keep looking, else stop
+            if (tx != NULL) {
+                for (uint32_t j = 0; j < tx_count; ++j) {
+                    if (mcu_uart_tx_list[j].pin != tx || 
+                        mcu_uart_tx_list[j].bank_idx != mcu_uart_rx_list[i].bank_idx) {
+                        continue;
+                    }
+                    // If UART is taken, break (pins never have >1 periph)
+                    if (reserved_uart[mcu_uart_rx_list[i].bank_idx - 1]) {
+                        uart_taken = true;
+                        break;
+                    }
+                    self->rx = &mcu_uart_rx_list[i];
+                    self->tx = &mcu_uart_tx_list[j];
+                    break;
+                }
+                if (self->tx != NULL || uart_taken) {
+                    break;
+                }
+            } else {
+                if (reserved_uart[mcu_uart_rx_list[i].bank_idx - 1]) {
+                    uart_taken = true;
+                    break;
+                }
+                self->rx = &mcu_uart_rx_list[i];
+            }
+        }
+    } else if (tx != NULL) {
+        // TX only case
+        for (uint32_t i = 0; i < tx_count; ++i) {
+            if (mcu_uart_tx_list[i].pin != tx) {
                 continue;
-
-            self->rx_pin = &mcu_uart_rx_list[i];
-            self->tx_pin = &mcu_uart_tx_list[j];
-
+            }
+            if (reserved_uart[mcu_uart_tx_list[i].bank_idx - 1]) {
+                uart_taken = true;
+                break;
+            }
+            self->tx = &mcu_uart_tx_list[i];
             break;
         }
+    } else {
+        mp_raise_ValueError(translate("Supply at least one UART pin"));
     }
 
-    if(self->rx_pin == NULL || self->tx_pin == NULL) {
-        mp_raise_RuntimeError(translate("Invalid UART pin selection"));
+    if (uart_taken) {
+        mp_raise_ValueError(translate("Hardware in use, try alternative pins"));
+    }
+
+    if(self->rx == NULL && self->tx == NULL) {
+        mp_raise_ValueError(translate("Invalid pins"));
+    }
+
+    if (is_onedirection && ((rts != NULL) || (cts != NULL))) {
+        mp_raise_ValueError(translate("Both RX and TX required for flow control"));
     }
 
     // Filter for sane settings for RS485
     if (rs485_dir != NULL) {
-      if ((rts != NULL) || (cts != NULL)) {
-        mp_raise_ValueError(translate("Cannot specify RTS or CTS in RS485 mode"));
-      }
-      // For IMXRT the RTS pin is used for RS485 direction
-      rts = rs485_dir;
+        if ((rts != NULL) || (cts != NULL)) {
+            mp_raise_ValueError(translate("Cannot specify RTS or CTS in RS485 mode"));
+        }
+        // For IMXRT the RTS pin is used for RS485 direction
+        rts = rs485_dir;
     }
     else {
-      if (rs485_invert) {
-        mp_raise_ValueError(translate("RS485 inversion specified when not in RS485 mode"));
-      }
+        if (rs485_invert) {
+            mp_raise_ValueError(translate("RS485 inversion specified when not in RS485 mode"));
+        }
     }
 
     // Now check for RTS/CTS (or overloaded RS485 direction) pin(s)
-    const uint32_t rts_count = sizeof(mcu_uart_rts_list) / sizeof(mcu_periph_obj_t);
-    const uint32_t cts_count = sizeof(mcu_uart_cts_list) / sizeof(mcu_periph_obj_t);
+    const uint32_t rts_count = MP_ARRAY_SIZE(mcu_uart_rts_list);
+    const uint32_t cts_count = MP_ARRAY_SIZE(mcu_uart_cts_list);
 
     if (rts != NULL) {
-      for (uint32_t i=0; i < rts_count; ++i) {
-        if (mcu_uart_rts_list[i].bank_idx == self->rx_pin->bank_idx) {
-          if (mcu_uart_rts_list[i].pin == rts) {
-            self->rts_pin = &mcu_uart_rts_list[i];
-            break;
-          }
+        for (uint32_t i=0; i < rts_count; ++i) {
+            if (mcu_uart_rts_list[i].bank_idx == self->rx->bank_idx) {
+                if (mcu_uart_rts_list[i].pin == rts) {
+                    self->rts = &mcu_uart_rts_list[i];
+                    break;
+                }
+            }
+        }
+        if (self->rts == NULL){
+            mp_raise_ValueError(translate("Selected RTS pin not valid"));
         }
-      }
-      if (self->rts_pin == NULL)
-        mp_raise_ValueError(translate("Selected RTS pin not valid"));
     }
 
     if (cts != NULL) {
-      for (uint32_t i=0; i < cts_count; ++i) {
-        if (mcu_uart_cts_list[i].bank_idx == self->rx_pin->bank_idx) {
-          if (mcu_uart_cts_list[i].pin == cts) {
-            self->cts_pin = &mcu_uart_cts_list[i];
-            break;
-          }
+        for (uint32_t i=0; i < cts_count; ++i) {
+            if (mcu_uart_cts_list[i].bank_idx == self->rx->bank_idx) {
+                if (mcu_uart_cts_list[i].pin == cts) {
+                    self->cts = &mcu_uart_cts_list[i];
+                    break;
+                }
+            }
+        }
+        if (self->cts == NULL){
+            mp_raise_ValueError(translate("Selected CTS pin not valid"));
         }
-      }
-      if (self->cts_pin == NULL)
-        mp_raise_ValueError(translate("Selected CTS pin not valid"));
     }
 
-    self->uart = mcu_uart_banks[self->tx_pin->bank_idx - 1];
+    if (self->rx) {
+        self->uart = mcu_uart_banks[self->rx->bank_idx - 1];
+    } else {
+        self->uart = mcu_uart_banks[self->tx->bank_idx - 1];
+    }
 
-    config_periph_pin(self->rx_pin);
-    config_periph_pin(self->tx_pin);
-    if (self->rts_pin)
-      config_periph_pin(self->rts_pin);
-    if (self->cts_pin)
-      config_periph_pin(self->cts_pin);
+    if (self->rx) {
+        config_periph_pin(self->rx);
+    }
+    if (self->tx) {
+        config_periph_pin(self->tx);
+    }
+    if (self->rts) {
+        config_periph_pin(self->rts);
+    }
+    if (self->cts) {
+        config_periph_pin(self->cts);
+    }
 
     lpuart_config_t config = { 0 };
     LPUART_GetDefaultConfig(&config);
 
     config.dataBitsCount = self->character_bits == 8 ? kLPUART_EightDataBits : kLPUART_SevenDataBits;
     config.baudRate_Bps = self->baudrate;
-    config.enableTx = self->tx_pin != NULL;
-    config.enableRx = self->rx_pin != NULL;
-    config.enableRxRTS = self->rts_pin != NULL;
-    config.enableTxCTS = self->cts_pin != NULL;
-    if (self->rts_pin != NULL)
-      claim_pin(self->rts_pin->pin);
-    if (self->cts_pin != NULL)
-      claim_pin(self->cts_pin->pin);
+    config.enableTx = self->tx != NULL;
+    config.enableRx = self->rx != NULL;
+    config.enableRxRTS = self->rts != NULL;
+    config.enableTxCTS = self->cts != NULL;
+    if (self->rts != NULL) {
+        claim_pin(self->rts->pin);
+    }
+    if (self->cts != NULL) {
+        claim_pin(self->cts->pin);
+    }
 
     LPUART_Init(self->uart, &config, UART_CLOCK_FREQ);
 
@@ -189,16 +241,18 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     // ..unfortunately this isn't done by the driver library
     uint32_t modir = (self->uart->MODIR) & ~(LPUART_MODIR_TXRTSPOL_MASK | LPUART_MODIR_TXRTSE_MASK);
     if (rs485_dir != NULL) {
-      modir |= LPUART_MODIR_TXRTSE_MASK;
-      if (rs485_invert)
-        modir |= LPUART_MODIR_TXRTSPOL_MASK;
+        modir |= LPUART_MODIR_TXRTSE_MASK;
+        if (rs485_invert) {
+            modir |= LPUART_MODIR_TXRTSPOL_MASK;
+        }
     }
     self->uart->MODIR = modir;
 
-    if (self->tx_pin != NULL)
-      claim_pin(self->tx_pin->pin);
+    if (self->tx != NULL) {
+        claim_pin(self->tx->pin);
+    }
 
-    if (self->rx_pin != NULL) {
+    if (self->rx != NULL) {
         // The LPUART ring buffer wastes one byte to distinguish between full and empty.
         self->ringbuf = gc_alloc(receiver_buffer_size + 1, false, true /*long-lived*/);
 
@@ -212,12 +266,12 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         // the capacity is one less than the size.
         LPUART_TransferStartRingBuffer(self->uart, &self->handle, self->ringbuf, receiver_buffer_size + 1);
 
-        claim_pin(self->rx_pin->pin);
+        claim_pin(self->rx->pin);
     }
 }
 
 bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
-    return self->rx_pin == NULL && self->tx_pin == NULL;
+    return self->rx == NULL && self->tx == NULL;
 }
 
 void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
@@ -229,16 +283,16 @@ void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
 
     gc_free(self->ringbuf);
 
-//    reset_pin_number(self->rx_pin);
-//    reset_pin_number(self->tx_pin);
+//    reset_pin_number(self->rx);
+//    reset_pin_number(self->tx);
 
-    self->rx_pin = NULL;
-    self->tx_pin = NULL;
+    self->rx = NULL;
+    self->tx = NULL;
 }
 
 // Read characters.
 size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t len, int *errcode) {
-    if (self->rx_pin == NULL) {
+    if (self->rx == NULL) {
         mp_raise_ValueError(translate("No RX pin"));
     }
 
@@ -284,7 +338,7 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
 
 // Write characters.
 size_t common_hal_busio_uart_write(busio_uart_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
-    if (self->tx_pin == NULL) {
+    if (self->tx == NULL) {
         mp_raise_ValueError(translate("No TX pin"));
     }
 
@@ -320,7 +374,7 @@ void common_hal_busio_uart_clear_rx_buffer(busio_uart_obj_t *self) {
 }
 
 bool common_hal_busio_uart_ready_to_tx(busio_uart_obj_t *self) {
-    if (self->tx_pin == NULL) {
+    if (self->tx == NULL) {
         return false;
     }
 
diff --git a/ports/mimxrt10xx/common-hal/busio/UART.h b/ports/mimxrt10xx/common-hal/busio/UART.h
index 3a326eb3a4..94a5fb02c0 100644
--- a/ports/mimxrt10xx/common-hal/busio/UART.h
+++ b/ports/mimxrt10xx/common-hal/busio/UART.h
@@ -45,10 +45,10 @@ typedef struct {
     uint32_t baudrate;
     uint8_t character_bits;
     uint32_t timeout_ms;
-    const mcu_periph_obj_t *rx_pin;
-    const mcu_periph_obj_t *tx_pin;
-    const mcu_periph_obj_t *cts_pin;
-    const mcu_periph_obj_t *rts_pin;
+    const mcu_periph_obj_t *rx;
+    const mcu_periph_obj_t *tx;
+    const mcu_periph_obj_t *cts;
+    const mcu_periph_obj_t *rts;
 } busio_uart_obj_t;
 
 #endif // MICROPY_INCLUDED_MIMXRT10XX_COMMON_HAL_BUSIO_UART_H
diff --git a/ports/nrf/boards/hiibot_bluefi/mpconfigboard.mk b/ports/nrf/boards/hiibot_bluefi/mpconfigboard.mk
index ad477e534a..b6614f8b3f 100644
--- a/ports/nrf/boards/hiibot_bluefi/mpconfigboard.mk
+++ b/ports/nrf/boards/hiibot_bluefi/mpconfigboard.mk
@@ -1,5 +1,5 @@
 USB_VID = 0x239A
-USB_PID = 0x0016
+USB_PID = 0x80B2
 USB_PRODUCT = "HiiBot BlueFi"
 USB_MANUFACTURER = "HiiBot"
 
diff --git a/ports/stm/common-hal/busio/UART.c b/ports/stm/common-hal/busio/UART.c
index c83479126a..0dc10c4e4c 100644
--- a/ports/stm/common-hal/busio/UART.c
+++ b/ports/stm/common-hal/busio/UART.c
@@ -259,7 +259,7 @@ void common_hal_busio_uart_never_reset(busio_uart_obj_t *self) {
 }
 
 bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
-    return self->tx->pin == NULL;
+    return (self->tx->pin == NULL && self->rx->pin == NULL);
 }
 
 void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
@@ -272,10 +272,15 @@ void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
         }
     }
 
-    reset_pin_number(self->tx->pin->port,self->tx->pin->number);
-    reset_pin_number(self->rx->pin->port,self->rx->pin->number);
-    self->tx = NULL;
-    self->rx = NULL;
+    if (self->tx) {
+        reset_pin_number(self->tx->pin->port,self->tx->pin->number);
+        self->tx = NULL;
+    }
+    if (self->rx) {
+        reset_pin_number(self->rx->pin->port,self->rx->pin->number);
+        self->rx = NULL;
+    }
+    
     ringbuf_free(&self->ringbuf);
 }
 
diff --git a/shared-bindings/watchdog/WatchDogMode.c b/shared-bindings/watchdog/WatchDogMode.c
index cc75a6ea44..369454c11b 100644
--- a/shared-bindings/watchdog/WatchDogMode.c
+++ b/shared-bindings/watchdog/WatchDogMode.c
@@ -74,14 +74,13 @@ mp_obj_t watchdog_watchdogmode_type_to_obj(watchdog_watchdogmode_t mode) {
 }
 
 STATIC const mp_rom_map_elem_t watchdog_watchdogmode_locals_dict_table[] = {
-    {MP_ROM_QSTR(MP_QSTR_NONE),   MP_ROM_PTR(&mp_const_none_obj)},
     {MP_ROM_QSTR(MP_QSTR_RAISE),  MP_ROM_PTR(&watchdog_watchdogmode_raise_obj)},
     {MP_ROM_QSTR(MP_QSTR_RESET),  MP_ROM_PTR(&watchdog_watchdogmode_reset_obj)},
 };
 STATIC MP_DEFINE_CONST_DICT(watchdog_watchdogmode_locals_dict, watchdog_watchdogmode_locals_dict_table);
 
 STATIC void watchdog_watchdogmode_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
-    qstr runmode = MP_QSTR_NONE;
+    qstr runmode = MP_QSTR_None;
     if (MP_OBJ_TO_PTR(self_in) == MP_ROM_PTR(&watchdog_watchdogmode_raise_obj)) {
         runmode = MP_QSTR_RAISE;
     }
diff --git a/shared-bindings/watchdog/WatchDogTimer.c b/shared-bindings/watchdog/WatchDogTimer.c
index 5411d0bef5..52bda4c779 100644
--- a/shared-bindings/watchdog/WatchDogTimer.c
+++ b/shared-bindings/watchdog/WatchDogTimer.c
@@ -40,6 +40,20 @@
 
 #include "supervisor/port.h"
 
+//| class WatchDogTimer:
+//|     """Timer that is used to detect code lock ups and automatically reset the microcontroller
+//|        when one is detected.
+//|
+//|        A lock up is detected when the watchdog hasn't been fed after a given duration. So, make
+//|        sure to call `feed` within the timeout.
+//|     """
+//|
+
+//|     def __init__(self, ):
+//|         """Not currently dynamically supported. Access the sole instance through `microcontroller.watchdog`."""
+//|         ...
+//|
+
 //|     def feed(self):
 //|         """Feed the watchdog timer. This must be called regularly, otherwise
 //|         the timer will expire."""
diff --git a/shared-bindings/watchdog/__init__.c b/shared-bindings/watchdog/__init__.c
index d0704b7cf7..76e6317294 100644
--- a/shared-bindings/watchdog/__init__.c
+++ b/shared-bindings/watchdog/__init__.c
@@ -34,18 +34,14 @@
 //|
 //| The `watchdog` module provides support for a Watchdog Timer. This timer will reset the device
 //| if it hasn't been fed after a specified amount of time. This is useful to ensure the board
-//| has not crashed or locked up. You can enable the watchdog timer using :class:`wdt.WDT`.
-//| Note that on some platforms the watchdog timer cannot be disabled once it has been enabled.
+//| has not crashed or locked up. Note that on some platforms the watchdog timer cannot be disabled
+//| once it has been enabled.
 //|
-//| The WatchDogTimer is used to restart the system when the application crashes and ends
+//| The `WatchDogTimer` is used to restart the system when the application crashes and ends
 //| up into a non recoverable state. Once started it cannot be stopped or
 //| reconfigured in any way. After enabling, the application must "feed" the
 //| watchdog periodically to prevent it from expiring and resetting the system.
 //|
-//| Note that this module can't be imported and used directly. The sole
-//| instance of :class:`WatchDogTimer` is available at
-//| :attr:`microcontroller.watchdog`.
-//|
 //| Example usage::
 //|
 //|     from microcontroller import watchdog as w
diff --git a/tools/extract_pyi.py b/tools/extract_pyi.py
index e590e25f1f..d749d202b3 100644
--- a/tools/extract_pyi.py
+++ b/tools/extract_pyi.py
@@ -52,7 +52,22 @@ def convert_folder(top_level, stub_directory):
     # Validate that the module is a parseable stub.
     total += 1
     try:
-        astroid.parse(stub_contents)
+        tree = astroid.parse(stub_contents)
+        for i in tree.body:
+            if 'name' in i.__dict__:
+                print(i.__dict__['name'])
+                for j in i.body:
+                    if isinstance(j, astroid.scoped_nodes.FunctionDef):
+                        if None in j.args.__dict__['annotations']:
+                            print(f"Missing parameter type: {j.__dict__['name']} on line {j.__dict__['lineno']}\n")
+                        if j.returns:
+                            if 'Any' in j.returns.__dict__.values():
+                                print(f"Missing return type: {j.__dict__['name']} on line {j.__dict__['lineno']}")
+                    elif isinstance(j, astroid.node_classes.AnnAssign):
+                        if 'name' in j.__dict__['annotation'].__dict__:
+                            if j.__dict__['annotation'].__dict__['name'] == 'Any':
+                                print(f"missing attribute type on line {j.__dict__['lineno']}")
+
         ok += 1
     except astroid.exceptions.AstroidSyntaxError as e:
         e = e.__cause__