ADS8674: How to add the channel adress in Output Data

Kilian Noetzold

Part Number: ADS8674

Tool/software:

In our application, data is very rarely corrupted. Only on a few devices and less than once a day.

The ADS8674 is operated in MAN_Ch_n mode as described in the datasheet on page 46. The first 16 bits of the SDO data should be zero, but this is not the case. This may be due to EMI or mechanical connection problems. In this case we discard the data. To improve this sanity check, we would like to enable the addition of the channel address to the data by setting the SDO bits to 01 in the "Feature Select Register". But it is not clear to me where data bits 8-5 of table 13 are in the data stream. Do we need to continue clocking after the 32nd falling edge of the SCLK signal in Figure 102? In that case we could not keep the 500ksps right?

Thanks.

10 months ago

0 Tom Hendrick 10 months ago

TI__Guru**** 181021 points

Hi Kilian,

Good question! To be honest, I'm not sure myself how this configuration works. I'll find out and get back to you as soon as possible - might not be until next week though given the Thanksgiving Holiday here in the US.

0 Kilian Noetzold 10 months ago in reply to Tom Hendrick

Intellectual 510 points

Hi Tom,

Thanks for looking into this.

0 Tom Hendrick 10 months ago in reply to Kilian Noetzold

TI__Guru**** 181021 points

Hi Kilian,

Setting the Feature Select Register to include the channel address adds an additional nine clock cycles to get the added detail out of the ADS8674. Normal operation is 32 clocks, bits 8-5 would be presented on the 33rd through 36th SCLK after the conversion data was presented. You can cut the transaction short if you like (you don't need to clock out all nine extra bits). This will impact the overall throughput as you noted above.

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ADS8674: How to add the channel adress in Output Data