STM8 bootloader UART write memory

[thaonguyen]

Hello,
I am developing a firmware for a host device to flash STM8S via UART.
My issue is when I send a write command, STM8 didn't response anything.
- Host sends write command: 0x31 0xCE, STM8 responsed ACK 0x79 . Host replies 0xFF
- Host sends 5 bytes address and checksum: 0x00 0x00 0x88 0x00 0x88, STM8 responsed ACK 0x79. Host replies 0xFF

- Host sends 6 bytes (1 byte: number of data, 4 bytes data and 1 byte checksum): 0x03 0x00 0x00 0x00 0x00 0x03

 STM8 didn't reply anything.
I attached serial capture image.
Please help me. it took me a long time to check it

 

[AA1]

Maybe it is missing the erase/write routines. See UM0560 - STM8 bootloader, section 3.8.1 RAM erase/write routines.

Also STM8S bootloader uses reply mode. Section 2.1.1 - The host must reply to all the bytes sent from the bootloader. I think 0xFF is the reply to 0x79. Maybe this works but reply byte should be the same as received. In this case 0x79.

[thaonguyen]

Hi @AA1 ,
I am sure that wrote RAM erase/write rountines to RAM start at address 0x0000A0, and I read back data is correct.
I just changed to reply same byte received, but it doesn't change, you can see image attached.
could you recheck this issue to help me?

 

[AA1]

UART settings is 1 start bit, 8 data bit, no parity bit, 1 stop bit?

 

[AA1]

Also try UART settings 1 start bit, 8 data bit, even parity, 1 stop bit.

[thaonguyen]

Hi @AA1 ,
I tried with wrong checksum then STM8 repsonses NACK
I also tried to use parity even bit but no change.

[Tesla DeLorean]

Why do you keep sending these 0xFF bytes?

Sending them after the command likely means it's expecting 256 bytes of data, not 4 bytes.

Also the protocol want's EVEN PARITY, ie 8E1, like the STM32 equivalent

https://www.st.com/resource/en/user_manual/um0560-stm8-bootloader-stmicroelectronics.pdf

[thaonguyen]

Hi @Tesla DeLorean ,
I am developing using UM560 document.
my stm8 is stm8s105 (stm8s-discovery). I wrote both 128 bytes and 256 bytes and it still isn't working.

pls help me with any idea.

[AA1]

I think the protocol for STM8S uses reply mode. UM0560 - STM8 bootloader Section 2.1.1 - The host must reply to all the bytes sent from the bootloader. Otherwise first 0xFF sent would be the first byte of 4 bytes address and the checksum would be wrong, which is not the case.

[thaonguyen]

@I just saw that stm8 is restarted after Host sends data.
any reason to do it restarted?

[Tesla DeLorean]

Watchdog? Writing to the wrong area causing a fault?

Perhaps use the Flash Demonstrator or ST tools to program via the loader, and monitor the COM port traffic.

[AA1]

.s19 file is not a binary file. How do you wrote RAM erase/write routines to RAM.

If above step is ok, other possibility is watchdog as Tesla DeLorean already said. Do you have watchdog enable by hardware in options bytes?

 

[thaonguyen]

Hi @AA1 ,
I don't use Watchdog.

I am writing content of routines file to RAM starting at address 0x0000A0. should it be correct?

[AA1]

If you don't' use watchdog, invalid opcode reset seems the only possibility. And this happens because code at address 0x0000A0 is invalid. Show me the first bytes at address 0x0000A0.

 

[AA1]

If the problem is solved, you should mark this topic as answered.