How to transmit more than 16 SPI bits?

Nick Wernicke

Other Parts Discussed in Thread: TMS320F28069

I did a thoroughly exhaustive search on this subject, even though I found literally *nothing* I feel like I am not the first person ever to try and do this. I need to transmit more than 16 SPI bits. According to the SPI guide, this is as simple as placing all the data into the 'FIFO Buffers', of which there can be up to 4 (16 bit data registers), which can be clocked in sequentially or with a 0 to 255 clock delay in between. Unfortunately, the guide is not so good as to reveal the addresses of said buffers, nor do the header files give any hints. The forums mention nothing about this topic, so I will be the first to ask:

How do I transmit more than 16 SPI bits with a c2000 processor?

over 14 years ago

0 DG44 over 14 years ago

Intellectual 330 points

Hi Nick,

I am uisng the SPI FIFO in the TMS320F28069 and in order to transmit 4 x 16-bits I write four times in the SPITXBUF register inside a for loop:

for (i=0; i<4; i++)

{ SpibRegs.SPITXBUF = Buffer[i]; }

These procedure, together with the SPI FIFO initialization was enough to transmit 4x 16-bits.

I hope that this can help you.

Regards,

Denise

0 Monica Zolog over 13 years ago in reply to DG44

Expert 1905 points

Hi!

If I need to read 96bits, I do the reading in a loop?

I haven't worked with the SPI yet, but I need to choose an ADC that has also SPI. Most of them send the result of the convesion in packets larger than 16 bits. I wonder how will I read the result and if it will be fast enough.

Thanks a lot,

Monica

0 Adnan Kurt over 11 years ago in reply to DG44

Intellectual 665 points

I think I could not understand your point in forming a for loop. Do you send the same 4*16bit data to the buffer 4 times? Or, should we place 4 off 16bit data to the buffer and that's all required?

Regards,
Adnan Kurt

0 DG44 over 11 years ago in reply to Adnan Kurt

Intellectual 330 points

Hi Adnan,

I just used the for loop to work with a buffer vector, but you can of course use a direct assignment as you mention.

Regards,

Denise

0 Adnan Kurt over 11 years ago in reply to DG44

Intellectual 665 points

Hi Denise,

Thanks for your reply. I have evaluated your code piece again, and got your point.

Regards,
Adnan

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How to transmit more than 16 SPI bits?