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USART protocol in bootloader : behavior of readout unprotect

LLouf
Associate II

Hello,

I have a small question about the bootloader, I guess this is common to all protocols but I have only tested with USART protocol. After sending the command readout unprotect, the application note states that :

"After the transmission of the [first] ACK byte, the bootloader erases all the Flash

memory sectors and it disables the read protection for the entire Flash memory. If the erase

operation is successful, the bootloader deactivates the RDP."

and

"For most STM32 products, the readout unprotect operation induces a mass erase of the

Flash memory, so the Host has to wait sufficient time after the second ACK and before

restarting connection."

So it left me wondering : is the mass erase performed before or after the second ACK is sent ? The second quote suggests that it happens after, but the first quote is a bit ambiguous on this point. So I measured the time between the first ACK and the second, which gave me around 23ms for a Nucleo F103RB (128kB of flash). It seems that the erase takes place between the two ACKs from this timing, but is there anyway to confirm that I don't have to wait around 40ms after receiving the second ACK ?

Best regards,

Laurent

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