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ADS112C04: RDATA cmd

Mahitha Ashok
Prodigy 10 points
Part Number: ADS112C04


Hello

I am a test engineer working on ATE(Automated Test Equipment) for ICs. 

I am currently working with your ADS112c04 device and have a few clarifications needed. 

1)Using the RDATA cmd, we can read out 2bytes of data. The 1st byte of data is okay while the 2nd byte is always latched to high(all 8bits). 

Since the master is the tester here, it cannot give an ACK after the 1st byte read. Will this affect the 2nd byte of data being available on the SDA line from the ADC device?

2) In continuous conversion mode, will DRDY go high gain only if the converted data is read out? In my case, DRDY is always low and does not seem to go back high at all. Is this a problem?

Looking forward to your reply.

Thanks

Mahitha

  • 0
    TI__Guru** 113765 points
    Hi Mahitha,

    Welcome to the E2E forum! The RDATA command is discussed on page 39 of the ADS112C04 datasheet. The device does expect to see an ACK after the first byte signaling the ADS112C04 that the first byte of the data was received as expected. The Master should be able to send the ACK when receiving data. When the ACK is received on the first byte, the communication ends as the ADS112C04 doesn't know what to do as the communication was indicated as failing.

    The DRDY pin is open drain, so there must be a pullup resistor on this pin. The DRDY pin is discussed in section 8.5.1.3 on page 36 of the datasheet. If the pullup resistor is missing, the DRDY will appear to never go high.

    If a previous conversion result is not read and the next conversion completes while in continuous mode, the DRDY should pulse high for 2 tmod periods signaling a new conversion result is ready to be read.

    Best regards,
    Bob B