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ADS127L01 SPI interface

Friedrich Kaufmann
Prodigy 90 points
Other Parts Discussed in Thread: ADS127L01, ADS127L01EVM

Hello,

I would like to use the ADS127L01.

I'm using the SPI interface and there it is possible to get the ADC results and to program registers. But I didn't find in the datasheet anything concerning mixing these two tasks. After the #DRDY signals goes low, I can shift out the results of the internal shift register. So I can't program the registers in that time range. Afterwards I can program registers of the ADC, but I must be ready before the next #DRDY signal is going low. I think, this can be a little bit difficult.
Perhaps there is the assumption, that the ADC is stopped, before any register is programmed using SPI interface. I can do this by setting the START pin low.
Is there any information available, concerning the practice using the SPI interface?

Further I'm interested, if the ADS127L01 needs a RESET after power up. Perhaps the device has an internal power up reset so no reset pulse is necessary at the #RESET pin of the ADC. At the evaluation board there is no connection of the RESET pin to the MCU. Perhaps I can connect the #RESET pin of the ADS127L01 directly to DVDD.

I appreciate any information available.

Thanks.

  • 0
    TI__Guru 66466 points

    Hello Friedrich,

    Thanks for posting your question.

    The interface on the ADS127L01 was not really intended for regular register updates while reading conversion results. Instead, this device is usually configured at start-up before START is taken high to begin conversions. However, that does not mean that you cannot do it and I can see when you may need to (i.e. if you need to update or enable the contents of the calibration registers). Please let me confer with our digital designers to know exactly how the interface will respond.

    Regarding the RESET, the ADS127L01 does issue its own internal power-on reset (POR) at start-up. It is not required to issue an additional RESET after power-up (more details are included on page 43 of the datasheet). The ADS127L01EVM only employs a software RESET option. The hardware connects the /PWDN/RESET pin to a pull-up resistor with an option to install a jumper to ground to evaluate the device in Power-Down Mode.

    Best Regards,