diff --git a/ports/atmel-samd/boards/cp32-m4/mpconfigboard.mk b/ports/atmel-samd/boards/cp32-m4/mpconfigboard.mk
index 86a7719b84..5cd3fe70ec 100644
--- a/ports/atmel-samd/boards/cp32-m4/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/cp32-m4/mpconfigboard.mk
@@ -11,6 +11,5 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = "W25Q128JV_PM"
 
-CIRCUITPY_PS2IO = 1
 # No I2S on SAMD51G.
 CIRCUITPY_AUDIOBUSIO = 0
diff --git a/ports/atmel-samd/boards/datalore_ip_m4/mpconfigboard.mk b/ports/atmel-samd/boards/datalore_ip_m4/mpconfigboard.mk
index aa5f47d400..398c54a119 100644
--- a/ports/atmel-samd/boards/datalore_ip_m4/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/datalore_ip_m4/mpconfigboard.mk
@@ -11,7 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 3
 EXTERNAL_FLASH_DEVICES = "GD25Q16C, W25Q16JV_IQ, W25Q16JV_IM"
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_NETWORK = 1
-MICROPY_PY_WIZNET5K = 5500
-CIRCUITPY_PS2IO = 1
diff --git a/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.mk b/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.mk
index 176ebac82c..4faa073876 100644
--- a/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.mk
@@ -11,7 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q16C
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_NETWORK = 1
-MICROPY_PY_WIZNET5K = 5500
-CIRCUITPY_PS2IO = 1
diff --git a/ports/atmel-samd/boards/grandcentral_m4_express/mpconfigboard.mk b/ports/atmel-samd/boards/grandcentral_m4_express/mpconfigboard.mk
index 423761c3f7..33542183b6 100644
--- a/ports/atmel-samd/boards/grandcentral_m4_express/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/grandcentral_m4_express/mpconfigboard.mk
@@ -11,5 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 2
 EXTERNAL_FLASH_DEVICES = "W25Q64JV_IQ, GD25Q64C"
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_PS2IO = 1
diff --git a/ports/atmel-samd/boards/hallowing_m4_express/mpconfigboard.mk b/ports/atmel-samd/boards/hallowing_m4_express/mpconfigboard.mk
index 0d891abc82..375be283a5 100644
--- a/ports/atmel-samd/boards/hallowing_m4_express/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/hallowing_m4_express/mpconfigboard.mk
@@ -11,7 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q64C
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_NETWORK = 1
-MICROPY_PY_WIZNET5K = 5500
-CIRCUITPY_PS2IO = 1
diff --git a/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.mk b/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.mk
index 5cab5bf43a..dca4e3706f 100644
--- a/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.mk
@@ -12,7 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q16C
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_PS2IO = 1
 # No I2S on SAMD51G
 CIRCUITPY_AUDIOBUSIO = 0
 
diff --git a/ports/atmel-samd/boards/kicksat-sprite/mpconfigboard.mk b/ports/atmel-samd/boards/kicksat-sprite/mpconfigboard.mk
index 706e551c5d..453be3b5ee 100644
--- a/ports/atmel-samd/boards/kicksat-sprite/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/kicksat-sprite/mpconfigboard.mk
@@ -14,3 +14,5 @@ LONGINT_IMPL = MPZ
 # Not needed.
 CIRCUITPY_AUDIOBUSIO = 0
 CIRCUITPY_DISPLAYIO = 0
+CIRCUITPY_NETWORK = 0
+CIRCUITPY_PS2IO = 0
diff --git a/ports/atmel-samd/boards/metro_m4_airlift_lite/mpconfigboard.mk b/ports/atmel-samd/boards/metro_m4_airlift_lite/mpconfigboard.mk
index 98d85ba826..bd837ebd6e 100644
--- a/ports/atmel-samd/boards/metro_m4_airlift_lite/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/metro_m4_airlift_lite/mpconfigboard.mk
@@ -11,7 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 3
 EXTERNAL_FLASH_DEVICES = "S25FL116K, S25FL216K, GD25Q16C"
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_NETWORK = 1
-MICROPY_PY_WIZNET5K = 5500
-CIRCUITPY_PS2IO = 1
diff --git a/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.mk b/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.mk
index 68b6f64065..e4d8b9428e 100644
--- a/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.mk
@@ -11,7 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 3
 EXTERNAL_FLASH_DEVICES = "S25FL116K, S25FL216K, GD25Q16C"
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_NETWORK = 1
-MICROPY_PY_WIZNET5K = 5500
-CIRCUITPY_PS2IO = 1
diff --git a/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk b/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk
index 4bd1d6e522..eff8bfe08a 100644
--- a/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk
@@ -12,7 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = "W25Q16JV_IM"
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_PS2IO = 1
 # No I2S on SAMD51G
 CIRCUITPY_AUDIOBUSIO = 0
 
diff --git a/ports/atmel-samd/boards/monster_m4sk/mpconfigboard.mk b/ports/atmel-samd/boards/monster_m4sk/mpconfigboard.mk
index a3db7dc890..84d1285c5b 100644
--- a/ports/atmel-samd/boards/monster_m4sk/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/monster_m4sk/mpconfigboard.mk
@@ -11,6 +11,3 @@ QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q64C
 LONGINT_IMPL = MPZ
-
-CIRCUITPY_AUDIOIO = 1
-CIRCUITPY_DISPLAYIO = 1
diff --git a/ports/atmel-samd/boards/pewpew_m4/mpconfigboard.mk b/ports/atmel-samd/boards/pewpew_m4/mpconfigboard.mk
index 54ec3d1d0e..bc2ae609ed 100644
--- a/ports/atmel-samd/boards/pewpew_m4/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/pewpew_m4/mpconfigboard.mk
@@ -17,7 +17,9 @@ CIRCUITPY_BITBANGIO = 0
 CIRCUITPY_FREQUENCYIO = 0
 CIRCUITPY_I2CSLAVE = 0
 CIRCUITPY_NEOPIXEL_WRITE = 0
+CIRCUITPY_NETWORK = 0
 CIRCUITPY_PIXELBUF = 0
+CIRCUITPY_PS2IO = 0
 CIRCUITPY_RTC = 0
 CIRCUITPY_TOUCHIO = 0
 CIRCUITPY_USB_HID = 0
diff --git a/ports/atmel-samd/boards/pybadge/mpconfigboard.mk b/ports/atmel-samd/boards/pybadge/mpconfigboard.mk
index 7e2cb64398..b5a240c66b 100644
--- a/ports/atmel-samd/boards/pybadge/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/pybadge/mpconfigboard.mk
@@ -12,8 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q16C
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_AUDIOIO = 1
-CIRCUITPY_DISPLAYIO = 1
 CIRCUITPY_GAMEPAD = 1
 CIRCUITPY_GAMEPADSHIFT = 1
 CIRCUITPY_STAGE = 1
diff --git a/ports/atmel-samd/boards/pybadge_airlift/mpconfigboard.mk b/ports/atmel-samd/boards/pybadge_airlift/mpconfigboard.mk
index 7e77b0feaf..e78789d741 100644
--- a/ports/atmel-samd/boards/pybadge_airlift/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/pybadge_airlift/mpconfigboard.mk
@@ -12,8 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q16C
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_AUDIOIO = 1
-CIRCUITPY_DISPLAYIO = 1
 CIRCUITPY_GAMEPAD = 1
 CIRCUITPY_GAMEPADSHIFT = 1
 CIRCUITPY_STAGE = 1
diff --git a/ports/atmel-samd/boards/pygamer/mpconfigboard.mk b/ports/atmel-samd/boards/pygamer/mpconfigboard.mk
index 0fce468d9f..a455690e19 100644
--- a/ports/atmel-samd/boards/pygamer/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/pygamer/mpconfigboard.mk
@@ -12,8 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q64C
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_AUDIOIO = 1
-CIRCUITPY_DISPLAYIO = 1
 CIRCUITPY_GAMEPAD = 1
 CIRCUITPY_GAMEPADSHIFT = 1
 CIRCUITPY_STAGE = 1
diff --git a/ports/atmel-samd/boards/pygamer_advance/mpconfigboard.mk b/ports/atmel-samd/boards/pygamer_advance/mpconfigboard.mk
index 8711738d4f..b6bb266308 100644
--- a/ports/atmel-samd/boards/pygamer_advance/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/pygamer_advance/mpconfigboard.mk
@@ -12,8 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = GD25Q64C
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_AUDIOIO = 1
-CIRCUITPY_DISPLAYIO = 1
 CIRCUITPY_GAMEPAD = 1
 CIRCUITPY_GAMEPADSHIFT = 1
 CIRCUITPY_STAGE = 1
diff --git a/ports/atmel-samd/boards/robohatmm1_m4/mpconfigboard.mk b/ports/atmel-samd/boards/robohatmm1_m4/mpconfigboard.mk
index 56f1617dbf..f18a3dbf46 100644
--- a/ports/atmel-samd/boards/robohatmm1_m4/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/robohatmm1_m4/mpconfigboard.mk
@@ -14,7 +14,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = "W25Q64JV_IQ"
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_PS2IO = 1
 # No I2S on SAMD51G
 CIRCUITPY_AUDIOBUSIO = 0
 # Make room for more stuff
diff --git a/ports/atmel-samd/boards/trellis_m4_express/mpconfigboard.mk b/ports/atmel-samd/boards/trellis_m4_express/mpconfigboard.mk
index ec37186c3a..bb0b7d1754 100644
--- a/ports/atmel-samd/boards/trellis_m4_express/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/trellis_m4_express/mpconfigboard.mk
@@ -12,7 +12,6 @@ EXTERNAL_FLASH_DEVICE_COUNT = 2
 EXTERNAL_FLASH_DEVICES = "W25Q64JV_IQ, GD25Q64C"
 LONGINT_IMPL = MPZ
 
-CIRCUITPY_PS2IO = 1
 # No I2S on SAMD51G
 CIRCUITPY_AUDIOBUSIO = 0
 
diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
index 88ddb49e01..df108664ad 100644
--- a/ports/atmel-samd/mpconfigport.mk
+++ b/ports/atmel-samd/mpconfigport.mk
@@ -16,10 +16,18 @@ endif
 
 # Put samd21-only choices here.
 ifeq ($(CHIP_FAMILY),samd21)
-# frequencyio not yet verified as working on SAMD21.
+# frequencyio not yet verified as working on SAMD21, though make it possible to override.
+ifndef CIRCUITPY_AUDIOMIXER
 CIRCUITPY_AUDIOMIXER = 0
+endif
+
+ifndef CIRCUITPY_FREQUENCYIO
 CIRCUITPY_FREQUENCYIO = 0
+endif
+
+ifndef CIRCUITPY_TOUCHIO_USE_NATIVE
 CIRCUITPY_TOUCHIO_USE_NATIVE = 1
+endif
 
 # SAMD21 needs separate endpoint pairs for MSC BULK IN and BULK OUT, otherwise it's erratic.
 USB_MSC_EP_NUM_OUT = 1
@@ -27,8 +35,24 @@ endif
 
 # Put samd51-only choices here.
 ifeq ($(CHIP_FAMILY),samd51)
-CIRCUITPY_SAMD = 1
+# No native touchio on SAMD51.
 CIRCUITPY_TOUCHIO_USE_NATIVE = 0
+
+# The ifndef's allow overriding in mpconfigboard.mk.
+
+ifndef CIRCUITPY_NETWORK
+CIRCUITPY_NETWORK = 1
+MICROPY_PY_WIZNET5K = 5500
+endif
+
+ifndef CIRCUITPY_PS2IO
+CIRCUITPY_PS2IO = 1
+endif
+
+ifndef CIRCUITPY_SAMD
+CIRCUITPY_SAMD = 1
+endif
+
 endif
 
 INTERNAL_LIBM = 1
diff --git a/ports/nrf/mpconfigport.mk b/ports/nrf/mpconfigport.mk
index 02bde3effa..f61d9f8eae 100644
--- a/ports/nrf/mpconfigport.mk
+++ b/ports/nrf/mpconfigport.mk
@@ -11,20 +11,33 @@ USB_SERIAL_NUMBER_LENGTH = 16
 LONGINT_IMPL = MPZ
 
 # Audio via PWM
+ifndef CIRCUITPY_AUDIOCORE
 CIRCUITPY_AUDIOCORE = 1
+endif
+
 CIRCUITPY_AUDIOIO = 0
+
+# The ifndef's allow overriding in mpconfigboard.mk.
+
+ifndef CIRCUITPY_AUDIOMIXER
 CIRCUITPY_AUDIOMIXER = 1
+endif
+
+ifndef CIRCUITPY_AUDIOPWMIO
 CIRCUITPY_AUDIOPWMIO = 1
+endif
+
+ifndef CIRCUITPY_AUDIOBUSIO
 CIRCUITPY_AUDIOBUSIO = 1
+endif
 
 # No I2CSlave implementation
 CIRCUITPY_I2CSLAVE = 0
 
-# enable NVM
-CIRCUITPY_NVM = 1
-
 # enable RTC
+ifndef CIRCUITPY_RTC
 CIRCUITPY_RTC = 1
+endif
 
 # frequencyio not yet implemented
 CIRCUITPY_FREQUENCYIO = 0
diff --git a/ports/stm32f4/mpconfigport.mk b/ports/stm32f4/mpconfigport.mk
index 928d53e67c..3ae0daaa08 100644
--- a/ports/stm32f4/mpconfigport.mk
+++ b/ports/stm32f4/mpconfigport.mk
@@ -15,18 +15,56 @@ LONGINT_IMPL = MPZ
 #Reduced feature set for early port
 CIRCUITPY_MINIMAL_BUILD = 1
 
+# The ifndef's allow overriding in mpconfigboard.mk.
+
+ifndef CIRCUITPY_BOARD
 CIRCUITPY_BOARD = 1
+endif
+
+ifndef CIRCUITPY_DIGITALIO
 CIRCUITPY_DIGITALIO = 1
+endif
+
+ifndef CIRCUITPY_ANALOGIO
 CIRCUITPY_ANALOGIO = 1
+endif
+
+ifndef CIRCUITPY_MICROCONTROLLER
 CIRCUITPY_MICROCONTROLLER = 1
+endif
+
+ifndef CIRCUITPY_BUSIO
 CIRCUITPY_BUSIO = 1
+endif
+
+ifndef CIRCUITPY_PULSEIO
 CIRCUITPY_PULSEIO = 1
+endif
+
+ifndef CIRCUITPY_OS
 CIRCUITPY_OS = 1
+endif
+
+ifndef CIRCUITPY_STORAGE
 CIRCUITPY_STORAGE = 1
+endif
+
+ifndef CIRCUITPY_RANDOM
 CIRCUITPY_RANDOM = 1
+endif
+
+ifndef CRICUITPY_USB_HID
 CIRCUITPY_USB_HID = 1
+endif
+
+ifndef CIRCUITPY_USB_MIDI
 CIRCUITPY_USB_MIDI = 1
+endif
+
+ifndef CIRCUITPY_NEOPIXEL_WRITE
 CIRCUITPY_NEOPIXEL_WRITE = 1
+endif
+
 
 #ifeq ($(MCU_SUB_VARIANT), stm32f412zx)
 #endif
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index c1199571bf..241fa10175 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -53,7 +53,7 @@ ifndef CIRCUITPY_DEFAULT_BUILD
 endif
 
 # Some features have no unique HAL component, and thus there's never
-# a reason to not include them. 
+# a reason to not include them.
 ifndef CIRCUITPY_ALWAYS_BUILD
   CIRCUITPY_ALWAYS_BUILD = 1
 endif
@@ -170,7 +170,7 @@ CIRCUITPY_NEOPIXEL_WRITE = $(CIRCUITPY_DEFAULT_BUILD)
 endif
 CFLAGS += -DCIRCUITPY_NEOPIXEL_WRITE=$(CIRCUITPY_NEOPIXEL_WRITE)
 
-# Only certain boards support NETWORK (Ethernet)
+# Enabled on SAMD51. Won't fit on SAMD21 builds. Not tested on nRF or STM32F4 builds.
 ifndef CIRCUITPY_NETWORK
 CIRCUITPY_NETWORK = 0
 endif