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ADC ADS7230 Manual Channel selection query?

Partha Murali
Prodigy 10 points

Dear Team,

Very Good Morning.

I am using ADS 7230 in Manual conversion mode and manual channel selection and i have a query.Kindly help me with this.

I would want to continuously toggle between channel 0 and channel 1 and read the respective outputs.

My init procedure :-

         Config with internal clk and no TAG bit

            Assert CS

            Send 16-bit data  0xE6FD with 16 clks --Manual trigger,Manual Channel and Internal clock

            De-assert CS

Query 1:-

Now , if i initiate conversion manually and read the output data, i would want to know whether the output belongs to channel 0 or channel 1 (since i have so far not issued the channel command)

Steps:-

           Assert CS

            Send 4-bit command 0xD with 4 clks

            Capture 12-bit data with 12 clks as converted result 

            De-assert CS           Assert CS

    The 12-bit data belongs to which channel???

 Query 2 :-

Suppose my current channel is channel 0 and then i issue a sequence like the following :-

            Assert CS

            Send 4-bit command 0'b 0001 with 4 clks

            Capture 12-bit data with 12 clks as converted result 

            De-assert CS           Assert CS

Now the 4 MSBs of my output belong to channel 0 or channel 1??? since it takes 4 clock cycles for the command to get executed and by then the 4 MSBS of the previous channel would have been shifted already.

Is my understanding right.

What is the right sequence to keep toggling between both the channels and get the right channel data??

Thanks in advance.

  • 0
    TI__Guru**** 168735 points

    Hi Partha,

    Welcome to our forum!  Someone will be addressing your question shortly.

  • 0
    TI__Mastermind 23235 points

    (For reference, use Figure 60 in the d/s) To determine which data is read out of the converter, you need to take into account the channel setting at the previous convert start. 

    From the above referenced figure, when CONVST is taken low, the channel that is selected is started converting.  When EOC goes high, the output is updated with the converted data.  The converted data can then be read after the next CONVST low using CS. 

    From your queries, you want to make sure that you are taking CONVST low after setting the command to set the channel select.  Since you are in manual mode, the device will not convert without the CONVST.