SPI Only sending 2 bytes and then TXTF flag goes high

[TomC1]

I am using an STM32H755, and attempting to send 35 bytes of data over SPI.

The data is copied into the TXDR, one byte at a time, but then only the first two bytes are send. The TSIZE is set to 35 and the CTSIZE counts down from 35 to 33, and then the TXDR bit goes high and no further data is sent. 

Could anyone suggest any reason why this may be happenning?

 

Thanks

[TDK]

If there are no error flags set then you’re probably missing something in your assumptions. Show a minimal (non-)working example.

[TDK]

Note that the TXFIFO can’t hold 35 bytes. If you’re blindly sending them all there immediately, that’s the problem.