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Using ADS1298 IC in wireless circuit

Derek Sinclair
Prodigy 90 points
Other Parts Discussed in Thread: ADS1298, ADS1299

Hopefully this question and problem makes sense.  I am experimenting with making a wireless EEG.  I stumbled across the ADS1298 chip and thought it would be useful in the project.  Not knowing much about it and being a bit confused, I have a few questions.  I will start with just one and hopefully the rest will come in time.  

So I ordered the chip individually, not part as any type of kit.  So what is the best way to simply test to be sure it is soldered properly and can output a signal from a function generator?  Will it need to be programmed first and if so what software should I use?

Sorry for the basic questions but just starting out.

Thank you,

Derek

  • 0
    TI__Guru 66446 points
    Hello Derek,

    Thank you for your interest in the ADS1298 and welcome to our forum!

    The ADS1298 itself does not need to be programmed, although there are internal registers that you can write to via SPI op-codes to change various settings (Gain, Data Rate, etc.). Are you using a microcontroller to talk to the device?

    To verify basic functionality, there are a few things you can check. First, verify all of the supplies, including the voltage on VCAP1 (1.2V) and the internal reference voltage (VREFP - VREFN). Second, if CLKSEL and START are pulled high, then /DRDY should begin pulsing at the default data rate of 500SPS.

    Once you have verified basic device functionality, you can try writing SPI commands to the device to read the ID register, configure an internal test signal, and collect data.

    For your reference, we also offer the ADS1299, which is even lower noise and especially equipped for EEG.

    Best of luck!
  • 0 in reply to Ryan Andrews
    Prodigy 90 points

    Thanks you for the reply!

    For right now, I was going to just use an Arduino Uno to power the ads.  Once the DRDY pulse is detected on an ocsilloscope I was going to use the Uno to try and capture data to first be read off of an SD card and then experiment with a wifi shield.

    I will try to verify functionality in the next day or so and let you know if I have any issues.

    But to be clear, for powering the ads, I need to follow the single supply connection in the datasheet correct?  With the external capacitors (VCAP1, VCAP2,...) ?  Also should I tie all supply pins together?

    Thanks again!

    Derek

  • 0 in reply to Derek Sinclair
    TI__Guru 66446 points
    Hi Derek,

    To power the ADS1298, all that is required is that you supply AVDD, AVSS, DVDD and DGND. The other internal supply rails (VCAPn) only require that you add the recommended bypass capacitors. You can refer to Figures 80 and 81 for single-supply and bipolar supply connections.

    Best Regards,