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There is an error in AN3155 Rev 15 page 26/48, Figure 15. After the first ACK you send either a special command that starts with 0xFFFy or the number of pages to be erased.


This is supported by the previous page Figure 16. The ACK is sent then if it is a special erase you send it the 2 bytes special code. If it is not then you send the number of bytes for the number of pages you want to erase, then the pages to erase, then the checksum.

Figure 16 says you send the number of bytes before you send the special code. That is not right.

ST Employee

Hi @KiptonM​ ,

thanks for the feedback, but I do not see any contradiction between the two figures. Both host and device side diagrams looks correct to me.



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I guess I can see how you might see it as O.K. but it is not.

"Receive Number of pages to be Erased N (Two bytes)"

Is misleading because it is not always the number of pages to be erased. It could be a special case.

I would change it to "Receive two bytes".

Next block: "0xFFFY received? Where Y can be be F, E, or D?"

(Yes direction is O.K.)

No direction add block:


"Interpret two bytes (MSB first) as 1 less than the number of pages to be erased.

Then continue as before.