I tried to set the Diagnostic Meter Mode by EVAL-AD7768FMCZ + EVAL-SDP-CH1Z.
I set the register 0x56 of the ADC Diagnostic Receive Select Register and 0x57 of the ADC Diagnostic Control Register, but the output data is still input voltage level.
Would you help how to set the diag mode?
Please make sure that inputs are disabled from the front end. Remove R134 and R139 for ch0, R155 and R151 for ch2 and similarly for the rest on EVAL BOARD.
Rest everything remains the same. Please…
We would like to know what do you mean by "data is still input voltage level". Have you connected an input on analog input pins?
The steps to set the diagnostic mode is
1. Disconnect the analog inputs to the channels which you wish to diagnose.
2. Enable the pre-charge buffers.
3. set the bits to 1 on the channels you wish to diagnose in register 0x56.
4. Set MODE A or B for channels in register 0x03.
5. Set the input scale (zero, +ve FS or -ve FS) in register 0x57 on the MUX A or B as per the MODE selection.
Please follow the above steps to use the Diagnostic Meter Mode.
Hi, Vikas J-san,
Thank you for your advice.
Yes, I tested while connecting an input analog signal, so I took off and retested.
I set CH0-4 as register 0x56 and +/-FS at register 0x57, but expected DOUT output (+/-VREF=+/-4.096V) wasn't obtained.
Is this output correct?
Rest everything remains the same. Please try this out. Make sure you select the appropriate Analysis channel as well.
I confirmed to remove R134 and R139 for ch0 and worked well.
Why isn't the positive/negative full-scale +/-Vref=4V, is it +/-3.78V?
As per page 91, Table 60. The device gives close to +ve or -ve full scale input. Hence, you can see around +/-3.78V.
HI, Vikas J-san,
Thank you for your support.
I understood that this function could work when I put the external switch to disconnect the input pins.