STM32L47 Bootloader v9.x SPI bug

[chaup]

Recently, I have been working on a project that intends to utilize the v9.x bootloader on an STM32L471VGT6 through the SPI 2 port. When utilizing the write memory command, I would find that the STM32L4 would occasionally have 0xFFFFFFFFFFFFFFFF written to its flash rather than the data I had requested. The frequency of this error increased the higher the baud rate of the SPI was and I found the issue was also much more prevalent in polling mode vs DMA mode. I happened to be reading through AN2606 and found in the version history for the L496 that theres is a known limitation on that processor with SPI writes. The behaviour listed was identical to what I was observing on the L4 and thankfully, the listed WA1 also solved the issue for the L4. Thus, I believe that the SPI write failure described for the L496 bootloader also exists on the L47 family and is currently undocumented. 

[Imen.D · Accepted solution]

Hello @chaup ,

First let me welcome you to the STM32 Community :) and thank you for having reported this point.

The known limitation (SPI write operation fail) exists also on the STM32L47 family.

An internal ticket ID 185529 is submitted in order to add this note in the coming release of AN2606.

(PS: Internal ticket ID 185529, is an internal tracking number and is not accessible or usable outside of ST).