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ADS7961-Q1: ADS7961 wrong data received on some of the channels

Uma Waghmare
Prodigy 30 points
Part Number: ADS7961-Q1
Other Parts Discussed in Thread: TMS320F28377D, ADS7961

We are using ADS7961 in manual mode interfacing with TMS320f28377D IC on SPI 

To configure the ic in Manual mode 0x1000 (channal 0 selected ) value is used  and i  m reading individual channal.

for chn0, chn1, chn3 and chn7  i m getting perfect result but for other channels such as 2,4,5,6,8 on-word i m getting wrong result.

follwoing is the values send in txbuf for n th frame and we r getting result in n+2 frame for selected channel .

chn0 = 0x1000; chn1 =0x1080;  chn2=0x1100; chn3=0x1180; chn4=0x1200;  etc 

Thanks in advance

Uma

  • 0
    TI__Mastermind 24940 points

    Hello Uma,

    It sounds like you are correctly sending the channel commands.

    Are the incorrect sample measurements related to the other input voltages? For example, if you have Ch1 at 1V and Ch2 at 2V, and when you read each channel, do you get 1V for both channels? Try setting each channel to a different voltage when testing, example, Ch0 to GND, Ch1 to 1V, ect.

    I would also suggest taking a scope shot of your digitial communications as well. This will help give a visual and help verify that what you expect to be sent to and from the device is in fact what is happenning. Please share these scope shots, including SDI, SDO, SCL, CS

    Regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 30 points

    Hello Cynthia,

    If we give  0V for ch0 then we are getting 0X00 hex Value correctly(D15 to D12 we are getting proper ch no) . 

    If we give 3V for ch0 then we are getting 0xFF hex value correctly(D15 to D12 we are getting proper ch no).

    Same thing is true for ch1 .

    But for ch2 we are getting (D15 to D12 value =0x3 hex)ch no and total o/p is 0x3ff0 when 3V given.

    It is showing wrong channel no we are expecting 0x2 hex insted of 0x3 hex similar things are happening for other channels mentioned in first post.

    I will send u snap shot of digital communication soon.

    Thanks in advance.

    Regards,

    Uma

     

  • 0 in reply to Uma Waghmare
    Prodigy 30 points

    Hello Cynthia,

    Problem is resolved .we are getting now correct result.

    We are configuring wrong clock polarity and clock phase now corrected and working fine.

    Thanks for all your effeort.

    Regards,

    Uma

  • 0 in reply to Uma Waghmare
    TI__Mastermind 24940 points
    I am glad that all is working correctly now!