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STM8 bootloader over UART - facing some issues

Question asked by su.ha on Apr 27, 2015

I'm following the instructions given in the STM8 bootloader manual for using the built-in ROM bootloader.

I have bootloader version 1.3 on board. When attempting to write the RAMroutines, I'm noticing the following:

I receive acknowledge bytes up until the final checksum byte (for the data bytechecksum), where I receive a NACK.

However, when I read from the memory where I have written into, I see that thedata bytes have been correctly written.

To illustrate, here's the command sequence I'm sending:

0x31 (write command), 0xCE (complement of write command)
0x00 (token reply byte, bootloader in reply mode)

0x00 (address byte MSB), 0x00 (address byte 2), 0x00 (address byte 3),0xA0 (address byte LSB), 0xA0 (address byte checksum)
0x00 (token reply byte, bootloader in reply mode)

0x0F (N: number of bytes to write - 1),
data bytes: 0x5f 0x3F 0x90 0x3F 0x96 0x72 0x09 0x00 0x8E 0x16 0xCD 0x60 0x650xB6 0x90 0xE7
data byte checksum (XOR of last two data bytes): 0x77

Then when I go to read the bytes written starting from address A0, I see thatthe data bytes above have been written correctly.

Why am I getting a NACK response to the final checksum (which is the XOR of theNth and N+1th data bytes)?