ADS8341: ADC Error with External vs Internal Clock

Hi Nandha,

Welcome to our e2e forum. 

It sounds like your problem is with the microcontroller rather than the ADS8341 itself.  Please post screen shots of the two controllers operating the ADS8341 in both internal and external clock modes - basically recreate figures 5 and 6 for us.  Ideally this would be with an o'scope, but a logic analyzer would work as well.

Hi Tom,

I can configure for external clock mode and I can recreate figure 5.

In case of Internal clock mode, how can I measure DCLK? What should be the input there? Even if we are using internal clock mode, is it necessary to give external clock? If so why? 

DCLK is always required, internal or external.  Internal clock mode uses an internal oscillator to do the conversion while DCLK strobes out the SDO.  External clock mode uses DCLK as the conversion clock.  Please review pages 13 and 14 of the datasheet.

Hi Nandha,

Have you found an issue/workaround?

Hi Tom, really sorry for the delay. 

I took waveform by comparing old and new microcontroller.

Old: CR16MCS9VJE7/NOPB     

New: FS32K146HAT0MLHLHR

Waveforms are not proper in new microcontroller. What may be the reasons?

I am getting 32 pulses in old uC with equal interval between each 8 pulses. Whereas in new uC I am getting a total of 40 pulses.

If channel 1 (yellow trace) is chip select, please keep that low through the entire 32 bit transfer.

I tried that as well. There is no change in the output. Is the clock pattern correct? Old uC is 8 bit and new one is 32 bit. Is that making any difference?

Can you share a schematic and details about what you think you are sending over as a command?  Zooming in a bit more on the screen shots would possible help as well.