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Errata for AN3155

Question asked by Timm Knape on May 30, 2018

Hi,

 

sorry, if this forum is the wrong place, but I did not find a better one :-)

 

In AN3155 (USART protocol used in the STM32 bootloader; DocID17066 Rev 7) on page 7 it is written:

 

2. for each command the host sends a byte and its complement (XOR = 0x00)

 

but if I XOR a byte and its complement I get 0xff as result, not 0x00.

 

I guess the correct meaning is restored if the XOR part is removed completely on checksums over a single byte. This also happens in byte 9 of the Read Memory Command (here the XOR should be replaced by complement). I do not know if any other documents are affected.

 

Sadly there is no contact in this document to address the problem directly.

 

Kind regards,

Timm.

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