Associate

Solved

STM32F303ZE Why is my SPI3 module transmitting 16-bits

Forum|Forum|8 years ago
January 22, 2018
4 replies
945 views

Posted on January 22, 2018 at 16:44

I have my SPI3 module configured as a master. I want it to transmit 8-bit words. Here is my setup as read from the chip while its executing. No matter what I do each time I write to SPI3->DR it transmits 16-bits what can I do? Please don't give any answers involving the HAL libraries as I am not able to use it.

Thanks

#stm32f-spi

SPI

This topic has been closed for replies.

Best answer by Tesla DeLorean

Posted on January 22, 2018 at 17:22

*((volatile uint8_t *)&SPI1->DR) = 0xAA; // volatile will be safer from the compiler folding the write

Guru

Posted on January 22, 2018 at 17:21

Write to the register with an appropriate cast so the bus transaction has the right width.

*((uint8_t *)&SPI1->DR) = 0xAA;

Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..

Tesla DeLoreanBest answer

Guru

Posted on January 22, 2018 at 17:22

*((volatile uint8_t *)&SPI1->DR) = 0xAA; // volatile will be safer from the compiler folding the write

Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..

Super User

Posted on January 22, 2018 at 17:29

And the explanation is under Data packing subchapter in the SPI chapter of RM.

JW