mazduino-mini6ch: fix PD14 stepper-enable vs critical-LED pin conflict

stepperEnablePin is PD14 (MCU-ENBL -> DRV8825 EN via the JP6 manual-
enable jumper), but mini6ch never overrode LED_CRITICAL_ERROR_BRAIN_PIN
so it inherited the rusEFI default of PD14 and claimed the pin first.
Point the critical-error LED at the dedicated onboard PB4 LED (PB7 is
the comms LED) to free PD14 for stepper enable.

Author: amrikarisma

CHANGELOG.md

@@ -35,6 +35,7 @@ All notable changes to Mazduino firmware are documented here.
 - Root `meta-info.env` (SHORT_BOARD_NAME=mazduino): generic board identifier removed; all builds now reference a named board variant
 
 ### Fixed
+- mazduino-mini6ch: PD14 pin conflict between the stepper driver enable (`stepperEnablePin`, MCU-ENBL → DRV8825 EN via JP6 manual-enable jumper) and the critical-error LED. mini6ch never overrode `LED_CRITICAL_ERROR_BRAIN_PIN`, so it inherited the rusEFI default of PD14 and claimed the pin before the stepper could use it. Moved the critical-error LED to the dedicated onboard PB4 LED (mini6ch has 3 LEDs — PB4, PB6, PB7 — with PB7 reserved for comms), freeing PD14 for stepper enable. Requires a firmware rebuild
 - Root `board_configuration.cpp`: removed forward declaration of `customBoardTsAction` which caused undefined reference linker error in CI unit test build
 - `EFI_EMBED_INI_MSD=FALSE` on mega100-512: the embedded TunerStudio INI file was contributing approximately 155KB to the firmware binary; disabling it reduced firmware from 488KB to 271KB
 - `EFI_EMBED_INI_MSD=FALSE` on all boards (mazduino-lite, mazduino-compact, mazduino-mini6ch, mazduino-mega100): CAN feature additions grew firmware beyond the 768KB linker budget; disabling INI embedding removes the 160KB ramdisk from flash. The TunerStudio INI is published as a GitHub Releases artifact instead

boards/mazduino-mini6ch/board.mk

@@ -4,6 +4,11 @@ BOARDCPPSRC += \
 
 endif
 
+# STM32F427VGT6: same core as F429 minus LTDC/DMA2D.
+# Enables SRAM3 (+64KB), correct flash driver, and EFI_IS_F42x features.
+# Clock stays at 168MHz so USB 48MHz remains exact (PLLN=336, PLLQ=7).
+IS_STM32F427 = yes
+
 DDEFS += -DEFI_WIDEBAND_FIRMWARE_UPDATE=FALSE
 DDEFS += -DRAM_UNUSED_SIZE=100
 DDEFS += -DSTM32_ADC_USE_ADC3=TRUE
@@ -16,3 +21,10 @@ DDEFS += -DEFI_EMBED_INI_MSD=FALSE
 
 # Mazda PFI — no GDI high-pressure fuel pump
 DDEFS += -DEFI_HPFP=FALSE
+
+# Move critical-error LED off PD14: that pin is the stepper driver enable
+# (MCU-ENBL -> DRV8825 EN via JP6 for manual enable). Default rusEFI critical
+# LED is PD14, which collided with stepperEnablePin. mini6ch has 3 onboard
+# LEDs (PB4, PB6, PB7); PB7 is the comms LED, so use the dedicated PB4 LED for
+# critical error. This frees PD14 for stepper enable.
+DDEFS += -DLED_CRITICAL_ERROR_BRAIN_PIN=Gpio::B4