Coreink power hold

m5stack/boards/M5STACK_CoreInk/board_init.c

@@ -0,0 +1,40 @@
+/*
+* SPDX-FileCopyrightText: 2026 M5Stack Technology CO LTD
+*
+* SPDX-License-Identifier: MIT
+*/
+
+#include "py/mpconfig.h"
+#include "esp_log.h"
+#include "driver/gpio.h"
+
+// CoreInk latches its own power rail on with GPIO12: running on battery, the
+// rail stays up only while that pin is driven high - or while the user keeps
+// the power button pressed. Out of reset the pad is an input, so there is a
+// window on every boot during which nothing holds the rail up.
+//
+// M5GFX does assert the pin, but only as a side effect of board autodetect,
+// which is reached from M5.begin() around 2s into a MicroPython boot. The
+// rail does not survive unaided for anything like that long. On battery the
+// consequences are that the board switches itself off after any reset, and
+// that powering it on means holding the power button down for seconds rather
+// than pressing it.
+//
+// Asserting the latch here - the first thing app_main does, before the
+// MicroPython task is created - closes that window to ~50ms.
+#define COREINK_POWER_HOLD_PIN  GPIO_NUM_12
+
+void CoreInk_board_startup(void) {
+    gpio_config_t power_hold = {
+        .pin_bit_mask = 1ULL << COREINK_POWER_HOLD_PIN,
+        .mode = GPIO_MODE_OUTPUT,
+        .pull_up_en = GPIO_PULLUP_DISABLE,
+        .pull_down_en = GPIO_PULLDOWN_DISABLE,
+        .intr_type = GPIO_INTR_DISABLE,
+    };
+    gpio_config(&power_hold);
+    gpio_set_level(COREINK_POWER_HOLD_PIN, 1);
+    ESP_LOGI("CoreInk", "power hold (GPIO12) asserted");
+
+    boardctrl_startup();
+}

m5stack/boards/M5STACK_CoreInk/mpconfigboard.cmake

@@ -4,6 +4,10 @@
 
 # coreink https://github.com/m5stack/m5stack-board-id/blob/main/board.csv#L8
 set(BOARD_ID 6)
+
+set(MICROPY_SOURCE_BOARD
+    ${MICROPY_BOARD_DIR}/board_init.c
+)
 set(MICROPY_PY_LVGL 0)
 
 # Font Support

m5stack/boards/M5STACK_CoreInk/mpconfigboard.h

@@ -7,5 +7,10 @@
 #define MICROPY_HW_BOARD_NAME "M5STACK CoreInk"
 #define MICROPY_HW_MCU_NAME "ESP32-S3"
 
+// Assert the power-hold latch (GPIO12) from app_main, before the
+// MicroPython task starts - see board_init.c.
+#define MICROPY_BOARD_STARTUP CoreInk_board_startup
+void CoreInk_board_startup(void);
+
 // If not enable LVGL, ignore this...
 #include "./../mpconfiglvgl.h"

m5stack/boards/M5STACK_CoreInk/sdkconfig.board

@@ -12,3 +12,12 @@ CONFIG_ESPTOOLPY_FLASHFREQ="80m"
 CONFIG_ESPTOOLPY_FLASHMODE_QIO=y
 
 CONFIG_FREERTOS_ENABLE_BACKWARD_COMPATIBILITY=y
+
+# CoreInk holds its power rail on with GPIO12, asserted at the top of app_main
+# (board_init.c). Validating the ~3.4MB app image costs ~900ms before app_main
+# is reached on every power-on reset, and on battery the rail does not survive
+# that long: the board switches off instead of restarting. Deep-sleep wakes
+# already skip validation; skip it on power-on too. This board has a single
+# factory partition, so there is no second image to fall back to if validation
+# were to fail.
+CONFIG_BOOTLOADER_SKIP_VALIDATE_ON_POWER_ON=y