STM32F101C8 Boot Loader reload?

[Mr_Overkill]

Hello,

 New here. I am working with a piece of consumer electronics equipment that uses a STM32F101C8 processor. the customer was doing an update to this unit and in the middle of the update, pulled the USB plug out of his computer bricking the unit. all attempts at using the manufacturers method of updating have failed. I have checked powers and grounds and all voltages are where they should be.
 I have ordered a ST Link V2 programmer that is due today. I am looking for advice/info On How to get a baseline. How to connect and erase the chip back to a stock setting essentially. reload a basic boot loader. something to attempt to get the chip back to a basic state so i can re-attempt the update process.

 I have the .BIN file from the MFG if that helps. 

 

My thinking is that if i can connect, get in, set up a basic starting point. even something like the blink program would probably reset the chip enough for the manufactures update process through the ST software and USB converter would work. it is a last ditch hail mary pass before we replace a very expensive board.

 there just has to be a way to do this without replacing the whole board. I SHOULD be able to re flash the MCU one way or another.

Please advise any sort of starting points. to quote the CEO from the movie "Margin Call"

"Please, speak as you might to a young child, or a golden retriever"

 

[Tesla DeLorean]

As I recollect the STM32F101 only supports the UART (USART1 PA9,PA10) as a means of update via the System Loader in ROM.

You'd need access to the serial port, the BOOTx pins, and reset or power cycling.

Probably at this point you'd be wanting to use STM32 Cube Programmer in UART/COM mode. You get one shot at connection per power-cycle / reset. Suggest 9600 baud 8E1 connection.

For JTAG connectivity, and ST-LINK/V2 and STM32 Cube Programmer should suffice.

You've provided no detail on the board, modes of connectivity, buttons or jumpers. So little idea what exactly you're working with.

No link to the manufacturers instructions or files.

A blinky app will not help you. You can partially or mass erase the part and just apply the the manufacturer's loader.

If the part is protected, it can be mass erased to clear, but you need to get all the material back on-board.

[TDK]

If the manufacturer has a custom bootloader on there, you would need to flash through that. However, if chip is dead, perhaps it does not.

If chip is locked (RDP2), you cannot recover.

Otherwise:

• Power the board through normal means.
• Connect GND, SWDIO, SWCLK between board and programmer, preferably also VDD_TARGET and NRST.
• Open STM32CubeProgrammer and hit connect.
• Upload firmware file to chip.
• Disconnect, power cycle, observe results.

[Mr_Overkill]

I had to photoshop multiple sections of the schematic together so you get all of the picture.

The factory update procedure uses a FTDI USB adapter. On the schematic you can see there is a 75C3232 IC that communicates to the STM32F101C8 IC,

 There is also an 24C16 eprom attached and there is a Header that is not populated that I can get the ST lInk connected to easily.

The factory program is a ST Link flash program. and the first step is to get the program to SEE the STM ic, which it does not. there is no response from the bootloader is the error i get. So I am hoping to plug in with the ST Link V2 programmer and see if i can get the STM32 to respond. and then from there, try and erase it or see what I can do to clear it and re program it etc.

[TDK]

Programmer header looks to be exposed. PA9/PA10 look to be used for the UART bootloader. Probably it is using the system bootloader and not a custom one, especially if standard ST programmer applications are used. In which case, you should be able to connect over USB->UART with STM32CubeProgrammer if you hold BOOT0 high during reset. If you can't do that, chip may be toast.

[Mr_Overkill]

I am working through getting my ST-LINK V2 programmer installed. Had some issues trying to get STMCube Programmer software to run on my windows 7 machine. I managed to get it to work on my Win11 laptop and will give it a try.

[Tesla DeLorean]

Needs to be using an USB-to-RS232 adapter, not going to work with a CMOS 3.3V level one.

Or a PC with a DB9 RS232 Serial port.

[Mr_Overkill]

Yes I have the factory USB to RS232 cable!