If doing ISP, do not power the eMMC through the programmer. Instead, use the device's original power supply or a bench power supply with a set current limit (e.g., 200mA) to safely inject voltage to the board. 6. Conclusion
eMMC support in Postal3 requires specific pin configurations (e.g., PB2 to PD5 and PB5 to PD6 on ATmega chips) and pull-up/pull-down resistors . postal3 emmc hot