Hi I am trying to bootload STM32F405RG using USART. The bootloader version is 3.1 I get the ACK back for erase memory and even when I send the address for the Write Memory. However I never get an ACK back when I start writing the data bytes. Please h

[sunny123]

I am using 9600 baud rate and even parity .

Address bytes sent with checksum is 08 00 00 00 08 ACK Received

[FBL]

Hello @sunny123​,

Could you please be more specific about NACK? Does it transmits a NACK byte or aborts the command?

Could you check if the address is valid? If yes, please provide us a dump/ log for better understanding of the issue.

You should refer to AN3155 section 3.6 Write Memory command for further details about the requirements to respect the order of the code sequence.

[Tesla DeLorean]

Provide a more complete data-gram flow, your situation is hard to understand/interpret.

My recollection of a data packet.. For FLASH use aligned addresses and perhaps 8-16 byte patterns

{ // Tx: 31 Write
BYTE data[25] = { 0x31, 0xCE, 0x20, 0x00, 0x00, 0x00, 0x20, // WRITE 0x20000000, w/SUM
0x0F, // 16 Bytes
0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, // Data pattern
0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF, 
0x0F }; // SUM