T48

WCH-link

Debug header

1. BO
   • 94 BOOT0
2. 3V3
   • no 3.3V on PCB. I guess connect to WCH-Link 3V3?
3. SWDCLK
   • PA14/SWCLK
4. SWDIO
   • PA13/SWDIO
5. ground
6. BOOT
   • U5 pin 4
   • SM16306SJ
   • https://www.lcsc.com/product-detail/LED-Drivers_Shenzhen-Sunmoon-Micro-SM16306S_C2830324.html
   • 4 => LE
   • BOOT1?

boot to high pin => seems to enable USB even with SWD plugged in

What exactly is this?

 ID 4348:55e0 WinChipHead

I think this is WchLink built into chip?

Unbrick

In theory we have all firmware (system ROM, bootloader, main firmware) and should be able to unbrick devices. However, I was unable to restore my devices

Theory: unrick issue is firmware is not at correct .hex location. Things that didn't seem to work to get firmware .hex file:

 objcopy --input-target=binary --output-target=ihex --set-start 0x08000000 t48_bootrom_2022-06-30.bin t48_bootrom_2022-06-30.hex

 objcopy --input-target=binary --output-target=ihex --change-addresses 0x08000000 t48_bootrom_2022-06-30.bin t48_bootrom_2022-06-30.hex  

 objcopy --input-target=binary --output-target=ihex t48_bootrom_2022-06-30.bin temp.hex
 objcopy --change-addresses 0x08000000 temp.hex t48_bootrom_2022-06-30.hex