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ADS131M08: ADS131M08, Reading single register

Saad Jabir
Prodigy 230 points
Part Number: ADS131M08

Tool/software:

Hello ,

We are trying to interpret the signals found on page 44 of the datasheet in a c code to read one single register of the ads131m08.

We would like to read the value of one register so we form the 16 bit command word and send it to the ADC.

While the adc is contentiously converting  the 8 analog channels. When is the right signal conditions TO READ THE REGISTER VALUE.?? 

Should we wait the drdy to go low and then have on word for the register followed by 8 (24 bits) words of the adc channels??

Why there is an OR 111aaaaannnnnn in the table at  page 42?

Do you have a simple code to just write the register and read it back for verification?

Thank you for your help !!

  • 0
    TI__Mastermind 45245 points

    Hi Saad,

    Please see my answers for your questions blow.

    1. Your question: When is the right signal conditions TO READ THE REGISTER VALUE.?? 

    Answer: You can read registers at any time as long as the ADC is properly powered up and reset.

    2. Your question: Should we wait the drdy to go low and then have on word for the register followed by 8 (24 bits) words of the adc channels??

    Answer: To read a register, no, you do not need to wait the /DRDY signal. If you only read a register and do not care about the conversion data of the ADC channels, you do not need to send more words. See the timing examples below.

    3. Your question: Why there is an OR 111aaaaannnnnn in the table at  page 42?

    Answer:  This is explained in the note at the bottom of the table 8-11 Command Definitions. When nnn nnnn is greater than 0 (you are reading more registers than one), the response begins with 111a aaaa annn nnnn, followed by the register data.

    4. Your question: Do you have a simple code to just write the register and read it back for verification?

    Answer: You can find the sample code in the section 9.16 Code Example in the data sheet or download SBAC254.zip (ADS131M0x Example Code) under Software Development from the link:   https://www.ti.com/product/ADS131M08#software-development

    You can find the following timing examples for writing and reading a register on ADS131M08 ADC:

    Timing 1: Use WREG command to write the GAIN register (04h address) with 0x0E0E data

    Timing 2: Use RREG command to read the GAIN register (04h address) , the register data (0x0E0E) is shown in the 2nd frame

    BR,

    Dale