diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index 3a0212d7fb..e96c00502c 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -143,6 +143,10 @@ msgstr ""
 msgid "%q must be between %d and %d"
 msgstr ""
 
+#: ports/atmel-samd/common-hal/busio/UART.c
+msgid "%q must be power of 2"
+msgstr ""
+
 #: py/argcheck.c
 msgid "%q must of type %q"
 msgstr ""
@@ -389,6 +393,7 @@ msgstr ""
 msgid "All event channels in use"
 msgstr ""
 
+#: ports/raspberrypi/common-hal/pulseio/PulseIn.c
 #: ports/raspberrypi/common-hal/rp2pio/StateMachine.c
 msgid "All state machines in use"
 msgstr ""
@@ -973,7 +978,7 @@ msgstr ""
 msgid "Expected an alarm"
 msgstr ""
 
-#: shared-module/_pixelbuf/PixelBuf.c
+#: shared-module/adafruit_pixelbuf/PixelBuf.c
 #, c-format
 msgid "Expected tuple of length %d, got %d"
 msgstr ""
@@ -1295,7 +1300,7 @@ msgstr ""
 msgid "Invalid buffer size"
 msgstr ""
 
-#: shared-bindings/_pixelbuf/PixelBuf.c
+#: shared-bindings/adafruit_pixelbuf/PixelBuf.c
 msgid "Invalid byteorder string"
 msgstr ""
 
@@ -1501,7 +1506,7 @@ msgstr ""
 msgid "Missing first_set_pin. Instruction %d sets pin(s)"
 msgstr ""
 
-#: shared-bindings/displayio/Group.c
+#: shared-bindings/busio/UART.c shared-bindings/displayio/Group.c
 msgid "Must be a %q subclass."
 msgstr ""
 
@@ -2348,7 +2353,7 @@ msgstr ""
 msgid "Unknown system firmware error: %04x"
 msgstr ""
 
-#: shared-bindings/_pixelbuf/PixelBuf.c
+#: shared-bindings/adafruit_pixelbuf/PixelBuf.c
 #, c-format
 msgid "Unmatched number of items on RHS (expected %d, got %d)."
 msgstr ""
@@ -2631,7 +2636,7 @@ msgstr ""
 msgid "buttons must be digitalio.DigitalInOut"
 msgstr ""
 
-#: shared-bindings/_pixelbuf/PixelBuf.c
+#: shared-bindings/adafruit_pixelbuf/PixelBuf.c
 msgid "byteorder is not a string"
 msgstr ""
 
@@ -2681,7 +2686,7 @@ msgid "can't cancel self"
 msgstr ""
 
 #: py/obj.c py/objint.c shared-bindings/i2cperipheral/I2CPeripheral.c
-#: shared-module/_pixelbuf/PixelBuf.c
+#: shared-module/adafruit_pixelbuf/PixelBuf.c
 msgid "can't convert %q to %q"
 msgstr ""
 
diff --git a/ports/atmel-samd/common-hal/busio/I2C.c b/ports/atmel-samd/common-hal/busio/I2C.c
index f7b8807976..d5a8f36f6a 100644
--- a/ports/atmel-samd/common-hal/busio/I2C.c
+++ b/ports/atmel-samd/common-hal/busio/I2C.c
@@ -71,6 +71,9 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     const mcu_pin_obj_t *scl, const mcu_pin_obj_t *sda, uint32_t frequency, uint32_t timeout) {
     uint8_t sercom_index;
     uint32_t sda_pinmux, scl_pinmux;
+
+    // Ensure the object starts in its deinit state.
+    self->sda_pin = NO_PIN;
     Sercom *sercom = samd_i2c_get_sercom(scl, sda, &sercom_index, &sda_pinmux, &scl_pinmux);
     if (sercom == NULL) {
         mp_raise_ValueError(translate("Invalid pins"));
diff --git a/ports/atmel-samd/common-hal/busio/SPI.c b/ports/atmel-samd/common-hal/busio/SPI.c
index 48ca8f843d..884c3e0414 100644
--- a/ports/atmel-samd/common-hal/busio/SPI.c
+++ b/ports/atmel-samd/common-hal/busio/SPI.c
@@ -92,6 +92,9 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     uint8_t miso_pad = 0;
     uint8_t dopo = 255;
 
+    // Ensure the object starts in its deinit state.
+    self->clock_pin = NO_PIN;
+
     // Special case for SAMR21 boards. (feather_radiofruit_zigbee)
     #if defined(PIN_PC19F_SERCOM4_PAD0)
     if (miso == &pin_PC19) {
diff --git a/ports/atmel-samd/common-hal/busio/UART.c b/ports/atmel-samd/common-hal/busio/UART.c
index 5aa13d076d..c33bf6f440 100644
--- a/ports/atmel-samd/common-hal/busio/UART.c
+++ b/ports/atmel-samd/common-hal/busio/UART.c
@@ -71,6 +71,10 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     uint32_t tx_pinmux = 0;
     uint8_t tx_pad = 255; // Unset pad
 
+    // Set state so the object is deinited to start.
+    self->rx_pin = NO_PIN;
+    self->tx_pin = NO_PIN;
+
     if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
@@ -85,6 +89,10 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         mp_raise_ValueError(translate("tx and rx cannot both be None"));
     }
 
+    if (have_rx && receiver_buffer_size > 0 && (receiver_buffer_size & (receiver_buffer_size - 1)) != 0) {
+        mp_raise_ValueError_varg(translate("%q must be power of 2"), MP_QSTR_receiver_buffer_size);
+    }
+
     self->baudrate = baudrate;
     self->character_bits = bits;
     self->timeout_ms = timeout * 1000;