Trouble with STM32H7 bootloader

[Mr_M_from_G]

Hello,

we have some trouble with STM32H742, trying to flash it via bootloader. It seems to accept only every second line of a hex file. We receive a hexfile with another microcontroller, build the bootloader commands and perform the bootloader communication. We send a write command of 16 bytes = 128 bits and receive an ACK after ca 50 µsec which seems to be reasonable according to the data sheet. After > 0.5msec we send the next write command which also receives ACK and locks like the first one on the oscilloscope watching UART Rx and Tx. But only every second one is really written to flash, the others are all bytes 0xFF.

Maybe important: we have Vcc only 1.8V but it is stable while flash is written

Anybody any experience with that?

Can we get the source code of the bootloader from ST?

Thanks for any help

Martin

[Mr_M_from_G]

Here is some news about it:

we found, that you have to program 32 bytes with one write command, otherwise it will fail with the next write command for the same 32 byte block. For this reason I would also assume that you might have trouble writing over a 32 byte boundary but we didn't check that.

I did not check how ST's Flash Loader demonstrator does it. Still a note in AN3155 would be great.

Martin