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ADS7038-Q1: auto-sequence mode

yan zhou
Prodigy 10 points
Part Number: ADS7038-Q1

Tool/software:

I am trying to implement the auto-sequence mode 

my sequence of commands:

1. Reset

2. Channel ID append enable

3. choose auto-sequence mode 

4. Channels 0, 1 and 6 activated for auto-sequencing

5. Start Sequencer

The SPI rate is 2M, transmit and receive FIFO are enable.

After these configuration steps ,  I can not receive the sampling result. Is there any missing step? Do I need to configure the sampling rate by OSC_SEL and CLK_DIV?

In auto-sequence mode , set SEQ_START to 1 for one time and it will trigger the continuous sampling without the rising edge of CS yes?

Please help to analyze this issue

Thanks a lot!

  • 0
    TI__Genius 11915 points

    Hi Yan,

    Thank you for the patience in waiting for a response over the US holidays. You do not need to configure the sampling rate with OSC_SEL and CLK_DIV. Auto-sequence mode does require the rise and fall of CS. The only difference between auto-sequence and manual mode is that you don't need to manually select the channel to read from by programming the MANUAL_CH_SEL register.

    Your configuration looks correct, so it seems like you only have to provide CS and SCLK to the device in order to get data from the selected auto-sequence channels. Since you have the Channel ID appended, it will appear as the last 4 bits in each SPI frame.

    Follow the below figure, sending 16 clocks rather than 12, and you should be able to see the last 4 bits SDO change according to the channels you have selected (0, 1, and 6). It could also be worthwhile for testing purposes to enable all channels for auto-sequencing, and you can see conversions cycle from 0-7, and back to 0 again.

    Please let me know if you are able to get this working by providing CS and 16 SCLKs while CS is low. If you are unable to, can you send a logic capture of the SPI lines showcasing the complete sequence you are sending?

    Regards,
    Joel