Postby ArT » Wed Apr 23, 2025 8:52 am
Please check what is current consumption of your board when you use external power supply DC/DC powering it from the same pins as programmer (programmer disconnected). Programmer is limiting to 100mA/200mA but sometimes it's not enough and the only solution is to desolder the chip and programm it in adapter. There are some tricks to lower external board power consumption, e.g. using slightly lower voltage (e.g. 2.6V for 3.3V chip) so MCU connected to FLASH will not start (voltage < BOD level) but it all depends on external board, sometimes internal capacity is so high that current is much above limits (chargins caps). Please check manual chapter 5 for more details.