mikeysklar · Oct 29, 2026 · Oct 29, 2026 · Oct 29, 2026 · Nov 1, 2026 · Nov 1, 2026
diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
@@ -861,6 +861,7 @@ msgstr ""
 #: ports/analog/common-hal/busio/SPI.c
 #: ports/espressif/common-hal/espidf/__init__.c
 #: ports/nordic/common-hal/_bleio/__init__.c
+#: shared-bindings/epaperdisplay/EPaperDisplay.c
 msgid "Invalid state"
 msgstr ""
 
@@ -1737,8 +1738,10 @@ msgstr ""
 #: ports/raspberrypi/common-hal/usb_host/Port.c
 #: shared-bindings/digitalio/DigitalInOut.c shared-bindings/emmcio/EMMC.c
 #: shared-bindings/i2cioexpander/IOPin.c shared-bindings/microcontroller/Pin.c
-#: shared-module/_airlift/__init__.c shared-module/max3421e/Max3421E.c
-#: shared-module/usb/core/Device.c shared-module/usb_host_audio/USBIn.c
+#: shared-module/_airlift/__init__.c
+#: shared-module/epaperdisplay/EPaperDisplay.c
+#: shared-module/max3421e/Max3421E.c shared-module/usb/core/Device.c
+#: shared-module/usb_host_audio/USBIn.c
 msgid "%q in use"
 msgstr ""
 

diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
@@ -39,6 +39,7 @@ CIRCUITPY_BUILTINS_POW3 ?= 0
 CIRCUITPY_BUSDEVICE ?= 0
 CIRCUITPY_COMPUTED_GOTO_SAVE_SPACE ?= 1
 CIRCUITPY_COUNTIO ?= 0
+CIRCUITPY_EPAPERDISPLAY_FAST ?= 0
 # Not enough RAM for framebuffers
 CIRCUITPY_FRAMEBUFFERIO ?= 0
 CIRCUITPY_FREQUENCYIO ?= 0
@@ -123,6 +124,10 @@ endif
 CIRCUITPY_ALARM ?= 1
 # Not enough room for both bitmaptools and bitmapfilter on most boards.
 CIRCUITPY_BITMAPFILTER ?= 0
+# Fast e-paper only fits on chips with 1MB flash.
+ifeq ($(HAS_1MB_FLASH),0)
+CIRCUITPY_EPAPERDISPLAY_FAST ?= 0
+endif
 CIRCUITPY_FLOPPYIO ?= $(CIRCUITPY_FULL_BUILD)
 CIRCUITPY_FRAMEBUFFERIO ?= $(CIRCUITPY_FULL_BUILD)
 CIRCUITPY_LOAD_NATIVE ?= 1

diff --git a/ports/espressif/boards/atmegazero_esp32s2/mpconfigboard.mk b/ports/espressif/boards/atmegazero_esp32s2/mpconfigboard.mk
@@ -15,3 +15,6 @@ CIRCUITPY_ESP_PSRAM_FREQ = 80m
 
 # Out of internal RAM with audiopwmio
 CIRCUITPY_AUDIOPWMIO = 0
+
+# Fast e-paper doesn't fit in internal RAM.
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
diff --git a/ports/espressif/boards/microdev_micro_s2/mpconfigboard.mk b/ports/espressif/boards/microdev_micro_s2/mpconfigboard.mk
@@ -15,3 +15,6 @@ CIRCUITPY_ESP_PSRAM_FREQ = 80m
 
 # Out of internal RAM with audiopwmio
 CIRCUITPY_AUDIOPWMIO = 0
+
+# Fast e-paper doesn't fit in internal RAM.
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
diff --git a/ports/espressif/mpconfigport.mk b/ports/espressif/mpconfigport.mk
@@ -34,6 +34,11 @@ IDF_TARGET_ARCH = xtensa
 CROSS_COMPILE = xtensa-$(IDF_TARGET)-elf-
 endif
 
+# Fast e-paper doesn't fit in flash on the C3, C5 and C6.
+ifneq ($(filter $(IDF_TARGET),esp32c3 esp32c5 esp32c6),)
+CIRCUITPY_EPAPERDISPLAY_FAST ?= 0
+endif
+
 # Use "internal flash" for CIRCUITPY drive.
 # Even thought it's an external flash chip, it appears as internal.
 INTERNAL_FLASH_FILESYSTEM = 1

diff --git a/ports/nordic/boards/TG-Watch/mpconfigboard.mk b/ports/nordic/boards/TG-Watch/mpconfigboard.mk
@@ -20,3 +20,5 @@ FROZEN_MPY_DIRS += $(TOP)/frozen/Adafruit_CircuitPython_LC709203F
 FROZEN_MPY_DIRS += $(TOP)/frozen/Adafruit_CircuitPython_DRV2605
 FROZEN_MPY_DIRS += $(TOP)/frozen/Adafruit_CircuitPython_BLE
 FROZEN_MPY_DIRS += $(TOP)/frozen/Adafruit_CircuitPython_BLE_Apple_Notification_Center
+
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
diff --git a/ports/nordic/mpconfigport.mk b/ports/nordic/mpconfigport.mk
@@ -98,6 +98,8 @@ ifeq ($(INTERNAL_FLASH_FILESYSTEM),1)
   CIRCUITPY_LTO_PARTITION = balanced
   CIRCUITPY_MSGPACK ?= 0
   CIRCUITPY_ULAB_OPTIMIZE_SIZE ?= 1
+  # Fast e-paper doesn't fit in what internal flash has left.
+  CIRCUITPY_EPAPERDISPLAY_FAST ?= 0
 else
   CIRCUITPY_USB_AUDIO ?= 1
 endif
@@ -125,6 +127,7 @@ OPTIMIZATION_FLAGS ?= -Os
 CIRCUITPY_LTO = 1
 CIRCUITPY_LTO_PARTITION = one
 ifeq ($(INTERNAL_FLASH_FILESYSTEM),1)
+  CIRCUITPY_EPAPERDISPLAY_FAST ?= 0
   CIRCUITPY_FULL_BUILD ?= 0
   CIRCUITPY_PULSEIO ?= 1
 endif

diff --git a/ports/raspberrypi/boards/wiznet_w5100s_evb_pico/mpconfigboard.mk b/ports/raspberrypi/boards/wiznet_w5100s_evb_pico/mpconfigboard.mk
@@ -11,6 +11,7 @@ EXTERNAL_FLASH_DEVICES = "W25Q16JVxQ"
 CIRCUITPY__EVE = 1
 CIRCUITPY_FLOPPYIO = 0
 CIRCUITPY_SSL = 1
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
 CIRCUITPY_USB_HOST = 0
 
 # The default is -O3. Change to -O2 because the build was overflowing.

diff --git a/ports/raspberrypi/boards/wiznet_w5100s_evb_pico2/mpconfigboard.mk b/ports/raspberrypi/boards/wiznet_w5100s_evb_pico2/mpconfigboard.mk
@@ -11,6 +11,7 @@ EXTERNAL_FLASH_DEVICES = "W25Q32JVxQ"
 
 CIRCUITPY__EVE = 1
 CIRCUITPY_SSL = 1
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
 
 # GPIO12-19 needed for picodvi, but GPIO16 is used for Wiznet.
 CIRCUITPY_PICODVI = 0

diff --git a/ports/raspberrypi/boards/wiznet_w5500_evb_pico/mpconfigboard.mk b/ports/raspberrypi/boards/wiznet_w5500_evb_pico/mpconfigboard.mk
@@ -11,6 +11,7 @@ EXTERNAL_FLASH_DEVICES = "W25Q16JVxQ"
 CIRCUITPY__EVE = 1
 CIRCUITPY_FLOPPYIO = 0
 CIRCUITPY_SSL = 1
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
 CIRCUITPY_USB_HOST = 0
 
 # The default is -O3. Change to -O2 because the build was overflowing.

diff --git a/ports/raspberrypi/boards/wiznet_w5500_evb_pico2/mpconfigboard.mk b/ports/raspberrypi/boards/wiznet_w5500_evb_pico2/mpconfigboard.mk
@@ -11,6 +11,7 @@ EXTERNAL_FLASH_DEVICES = "W25Q32JVxQ"
 
 CIRCUITPY__EVE = 1
 CIRCUITPY_SSL = 1
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
 
 # GPIO12-19 needed for picodvi, but GPIO16 is used for Wiznet.
 CIRCUITPY_PICODVI = 0

diff --git a/ports/raspberrypi/boards/wiznet_w55rp20_evb_pico/mpconfigboard.mk b/ports/raspberrypi/boards/wiznet_w55rp20_evb_pico/mpconfigboard.mk
@@ -11,6 +11,7 @@ EXTERNAL_FLASH_DEVICES = "PY25Q16HB"
 CIRCUITPY_WIZNET = 1
 CIRCUITPY__EVE = 1
 CIRCUITPY_SSL = 1
+CIRCUITPY_EPAPERDISPLAY_FAST = 0
 CIRCUITPY_USB_HOST = 0
 
 OPTIMIZATION_FLAGS = -O2
diff --git a/ports/stm/mpconfigport.mk b/ports/stm/mpconfigport.mk
@@ -19,6 +19,11 @@ ifeq ($(INTERNAL_FLASH_FILESYSTEM),1)
   OPTIMIZATION_FLAGS ?= -Os
 endif
 
+# Fast e-paper doesn't fit in flash on the F401 and F411.
+ifeq ($(MCU_VARIANT),$(filter $(MCU_VARIANT),STM32F401xE STM32F411xE))
+        CIRCUITPY_EPAPERDISPLAY_FAST ?= 0
+endif
+
 ifeq ($(MCU_VARIANT),STM32F407xx)
         UF2_FAMILY_ID ?= 0x6d0922fa
 endif

diff --git a/py/circuitpy_defns.mk b/py/circuitpy_defns.mk
@@ -1180,6 +1180,7 @@ $(filter $(SRC_PATTERNS), \
 	_airlift/transport.c \
 	displayio/bus_core.c \
 	displayio/display_core.c \
+	epaperdisplay/lag_drive.c \
 	usb/utf16le.c \
 )
 

diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
@@ -414,6 +414,11 @@ typedef long mp_off_t;
 #define CIRCUITPY_BUSIO_SPI_ASYNC (0)
 #endif
 
+// Normally set from CIRCUITPY_EPAPERDISPLAY_FAST in the .mk files. zephyr-cp doesn't set it.
+#ifndef CIRCUITPY_EPAPERDISPLAY_FAST
+#define CIRCUITPY_EPAPERDISPLAY_FAST (0)
+#endif
+
 // These CIRCUITPY_xxx values should all be defined in the *.mk files as being on or off.
 // So if any are not defined in *.mk, they'll throw an error here.
 

diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
@@ -317,6 +317,11 @@ CFLAGS += -DCIRCUITPY_QSPIBUS=$(CIRCUITPY_QSPIBUS)
 CIRCUITPY_EPAPERDISPLAY ?= $(CIRCUITPY_DISPLAYIO)
 CFLAGS += -DCIRCUITPY_EPAPERDISPLAY=$(CIRCUITPY_EPAPERDISPLAY)
 
+# Fast e-paper updates: EPaperDisplay's write_previous_ram_command, fast, lag_frames
+# and clean(). Ports and boards short on flash turn it off.
+CIRCUITPY_EPAPERDISPLAY_FAST ?= $(CIRCUITPY_EPAPERDISPLAY)
+CFLAGS += -DCIRCUITPY_EPAPERDISPLAY_FAST=$(CIRCUITPY_EPAPERDISPLAY_FAST)
+
 CIRCUITPY_I2CDISPLAYBUS ?= $(CIRCUITPY_DISPLAYIO)
 CFLAGS += -DCIRCUITPY_I2CDISPLAYBUS=$(CIRCUITPY_I2CDISPLAYBUS)
 

diff --git a/shared-bindings/displayio/__init__.c b/shared-bindings/displayio/__init__.c
@@ -84,11 +84,17 @@
 //|     Once you release a builtin display (one that is initialized automatically, not by user code),
 //|     the display will remain released even if you restart the CircuitPython VM, for instance by typing ctrl-D.
 //|     The display is not re-initialized until you do a hard reset or manually initialize it again.
+//|
+//|     If an EPaperDisplay using ``lag_frames`` can't get its bus, this waits up to 30 seconds and then
+//|     raises `RuntimeError` with every display left as it was, so you can free the bus and call it again.
 //|     """
 //|     ...
 //|
 //|
 static mp_obj_t displayio_release_displays(void) {
+    #if CIRCUITPY_EPAPERDISPLAY_FAST
+    displayio_prepare_release_displays();
+    #endif
     common_hal_displayio_release_displays();
     return mp_const_none;
 }