So new problem while trying to bypass non functioning SWD...
Using a working NUCLEO_H723 I can use the STM32CubeProgrammer to access it via STLINK (internal and external) as well as via USB DFU after reset with BOOT0 high.
From my reading of AN2606, once the bootloader has initialized, it cycles through the various options in sequence till it gets a connection (CAN first, then USARTx, I2Cx, SPIx, USB). The diagram indicates USB cable detection so I'm assuming as long as it isn't connected that the other peripherals will be checked.
I'm unclear on it checks all the possibilities for each USARTx (and I2C, SPI) or just one of them ? The only readily accessible USART is UART3 on CN10 of the Nucleo so I've started with that. Tried using RTS/DTR for BOOT0 and reset control but can't get the timing/polarity correct so just holding BOOT0 high and tried both manual reset and a pulse from DTR. I can see a single 0x7F being sent but no reply, then one more 0x7F after 2 seconds before it times out and quits.
The board works otherwise so assuming I don't have a fried serial port but maybe will have to connect to another to make sure. Open to suggestions, thanks,
