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DAC7760 (Eval-Board) interfacing with TMS320F28377D (EVAL-BOARD),trying to communicate with SPI.

Prashanth Prakash41
Intellectual 320 points
Other Parts Discussed in Thread: DAC7760, TMS320F28377D

Hi , 

I am using the DAC7760 (Eval-Board) interfacing with TMS320F28377D (EVAL-BOARD),trying to  communicate with SPI .

The data-sheet says default frame is 24 bits wide. So can I send 8-bits in each transmission  (from MCU), and make 3 such transmissions to complete the entire 24-bit wide frame, instead of 24 bits(entire frame) in one transmission ?

Also I want to know, if I need to give any delay between consecutive transmissions ? Because I observed that if I give consecutive transmissions without any delay, there  is high chance of just the last/recent transmission being transmitted correctly.

Thank You,

Prashanth 

  • 0
    TI__Genius 10615 points

    Hi Prashanth,

    Prashanth Prakash41 said:
    The data-sheet says default frame is 24 bits wide. So can I send 8-bits in each transmission  (from MCU), and make 3 such transmissions to complete the entire 24-bit wide frame, instead of 24 bits(entire frame) in one transmission ?

    There should be no problem with this as long as the LATCH rising edge is not issued until after the 3x 8-bit frames are sent.

    Prashanth Prakash41 said:
    Also I want to know, if I need to give any delay between consecutive transmissions ? Because I observed that if I give consecutive transmissions without any delay, there  is high chance of just the last/recent transmission being transmitted correctly.

    This would depend on the SPI CLK frequency, if you are violating any timing specifications it will cause some problems, but if the SPI CLK is fairly slow, then such issues should not arise.

    I think the best way to address your issue is to share with me a few oscilloscope captures of the SPI frames that you are sending including SCLK, SDI and LATCH. This will allow me to make better recommendations for your setup.