U85 module programming
This module can be programmed in two different ways: with programming or by UART.
Connect "PWRON" line to VBAT line - to power on module.
You need to connect SWDIO, SWCLK, NRST, GND to your programmer (ST-Link for example).
Notice that NRST must be connected!
You need to select "Connect under Reset" and Reset mode: "Hardware Reset" in options of your programmer.
This STM32 have integrated UART bootloader (DFU), that is stored in ROM (it is not possible to erase it).
This bootloader can be used for loading firmware to MCU without programmer. Only USB-UART converter is needed.
You need to connect BOOT0 line to GND and reset module to enter to bootloader.
Use "STM32CubeProgrammer" utility for working with bootloader. Select "UART" mode near "Connect" button.
Original firmware of the module is locked, so you will have such message after connection:
So you need to set "Read Unprotect" switch (it is at right) and try to connect again.
Pinout for UART programming:
