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Read ADS1211U using Raspberry pi

Mans Sterner
Prodigy 10 points
Other Parts Discussed in Thread: ADS1211

Hi!

I'm currently working on a project where I want to read a voltage using the ADS1211U and convert it to my Raspberry Pi 2, model B.

I'm a complete newbie to this kind of work so I have a few questions:

1. What is the simplest way to connect the ADC to the Pi? I mean, which pins are essential for the SPI protocol to even function properly and where do I connect them to the Pi? Do I just connect the unused pins to ground?

2. How does the typical sampling procedure look like? Do I just write one instruction byte to the ADC and then continuously read from the DOR register, or do I have to keep sending instruction bytes between every sample?

The ADS1211U datasheet can be found here: w w w.ti.com/lit/ds/sbas034b/sbas034b.pdf

and the Pi pinout can be found here: w w w.raspberry-pi-geek.com/var/rpi/storage/images/media/images/raspib-gpio/12356-1-eng-US/RasPiB-GPIO_lightbox.png

Any help would be greatly appreciated!

  • 0
    TI__Guru* 97775 points
    Mans,


    To be honest, I'm not very familiar with the Raspberry Pi. We generally are more helpful with questions involving the data converters themselves.

    Using the SPI to communicate with the ADS1211, it is important to connect the SCLK, SDIO, SDOUT, and /CS. It is also important to use the /DRDY as an interrupt to know when to get a data reading. It's likely that you'll be using the Slave Mode, so that the MODE pin will be connected to ground. Figures 14-20 will help a lot in figuring out digital communications.

    It is also important to have a way to review the waveforms that are used in communications. Getting an oscilloscope or logic analyzer is extremely useful to getting all of the communications debugged.

    Out of curiosity, this is a bit of an older device and it's a more complicated communications scheme than some of our other devices. Would you be interested in a newer device? Most of our newer devices have evaluation modules that might be of better use to you. What exactly are you measuring?


    Joseph Wu