TMS320F28379D: SPIRXBUF buffer bit length

Hi Aditya,

Aditya Ghule1 said:

However, when I read the SPIRXBUF buffer, I get a 10 bit word with a 1 as the MSB. Should I discard the 10th bit for the word I am reading?

Have you only tried to transmit one word or does this happen with any data that you transmit? Is the data you receive correct?

Best Regards,

Marlyn

Hi Marlyn,

This happens with any data I transmit. I have been masking the 10th bit to get the data.  The data I receive seems to be correct. I had not masked the data before so I used to get an additional bit of the word, but masking the data seems to work. I was  curios how the buffer was providing an extra bit for a setting at a lower bit length.

Thank you,

Aditya

Hi Aditya,

Would it be possible to see how you are initializing the SPI module and how you transmit the data? I will try to duplicate this on my side as well. 

Best Regards,

Marlyn

Hi Marlyn,

Sorry about the delay in replying here are the settings I am using:

SpiaRegs.SPICCR.bit.CLKPOLARITY =1;
SpiaRegs.SPIBRR.bit.SPI_BIT_RATE = 40;
SpiaRegs.SPICCR.bit.SPILBK = 0x0;

SpiaRegs.SPICCR.bit.SPICHAR = 8;   
SpiaRegs.SPITXBUF = 0x01;
while(SpiaRegs.SPISTS.bit.INT_FLAG == 0);
data= SpiaRegs.SPIRXBUF ;

Thank you,

Aditya

Hi Aditya,

No worries, thank you for sharing your settings. I will provide an update by 3/21.

Best Regards,

Marlyn

Hi Aditya,

Aditya Ghule1 said:

SpiaRegs.SPICCR.bit.SPICHAR = 8;   
SpiaRegs.SPITXBUF = 0x01;

I noticed that you are transmitting a one (8 bits) before you read. What happens if you transmit 0x00 instead? Note: SPIRXBUF contains the most recently received character, right-justified, plus any bits that remain from previous transmission(s) that have been shifted to the left.

Best Regards,

Marlyn

Hi Marlyn, 

Thanks I will check that.  I am transmitting the 0x01 as dummy data as I am only reading the transmitted data from the device. I will try transmitting a 0x00 in the coming week to check if that makes a difference.

Thank you,

Aditya Ghule