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ADS7961-Q1: ADS7961 change channel error

Kenshiro Hoshi
Prodigy 20 points
Part Number: ADS7961-Q1
Other Parts Discussed in Thread: ADS7961, ADS7955

Tool/software:

I combines Renesas microcomputer RH850 and ADS7961
After power up, configure the device/ADS7955 to operate in manual mode without any other configuration.
You are trying to change another channel (for example, channel 2).
But in the next frame, the channel is not changed.
The device keeps output channel 0 (default).
Also, if you apply a voltage only to CH0 when you are outputting another channel, the voltage will be detected even though the channel is not CH0.

Datasheet says ;

"The device continues its operation in Manual mode channel 0 through out the programming sequence and outputs
valid conversion results. It is possible to change channel, range, GPIO by inserting extra frames in between two
programming blocks. It is also possible to bypass any programming block if the user does not intent to use that
feature." (SLAS605A,p.27,Figure 49. Device Power-Up Sequence,note (1).)

Is any other setup required?

Here's a snippet of the actual source code

  • 0
    TI__Expert 6000 points

    Hi Hoshi-san,

    It is hard to debug issues with the device from source code alone, particularly from an unfamiliar MCU. Are you able to provide a logic capture file (preferred) or screenshots, or an oscilloscope capture of the SPI communication pins? 

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 20 points

    Hi,Joel,

    The screen shot of the oscilloscope related to SPI communication is attached below.
    Light blue is CS, yellow is SCLK, blue is DIN, and purple is DOUT.
    As shown in the first image, a command to specify each channel is sent to DIN, but only CH0 is displayed in DOUT. (The upper 4 bits of DOUT are not changed according to the command sent.)
    In the second image, the voltage is applied only to CH0 of the ADC. However, as shown in the first image, all channels are output as CH0, so the voltage for CH0 is output for all channels.

    Also, when I checked each channel one by one, the result is that only CH0 is output as well. The circuit should be connected without any problems, but I would appreciate it if you could let me know if you notice anything.


  • 0 in reply to Kenshiro Hoshi
    TI__Expert 6000 points

    Hi Hoshi-san, 

    From your latest post, it seems like you were able to resolve this issue, but you are seeing a bit shift. Is this the case? If so, can I close this thread and we can move our focus to the other thread?

    https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/1431060/ads7961-q1-manual-mode-channel-bit-error

    Regards,
    Joel