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ADS7861/ADS1251 all synchronously sampling

Other Parts Discussed in Thread: ADS1251, ADS7861, OMAPL138, ADS1278, ADS1015, ADS8558, ADS1274

Cor van Mil wrote the following post at Wed, Feb 10 2010 12:17 AM:

Hello Rick,

Thank you very much for your help.

I want to use three ADS7861 in parallel  and two ADS1251 in parallel. All should be synchronously sampling at 10KHz. I want to target them on the OMAPL138 processor.

Cor

  • Moved this discussion from the Code Composer forum.

    Cor, can you describe a little more about your application? As I mentioned in the CCS forum, doing what you've suggested will require at least 5 serial interfaces, perhaps 7. That can be challenging even with a powerful processor like the OMAP.

    Would a part like the ADS1278 perhaps be a better solution? Hard to say without knowing what you're trying to accomplish. Please give us some more detail and we can maybe come up with an optimum solution.

  • Rick,

    The application is as follows. I want to measure two sensors at 24bit resolution and measure 3 analog encoders with 2 differential channels each (sin and cos) at least 12bit resolution. All signals must be sampled synchonously and at 10KHz sample rate. I like the ADS1278 especially the passband filter characteristics that are much better then the ADS1251. So in total I need 8 channels.Do you think the data rate will be too high for this processor? All signal must be digitally filterred with 4 section 2nd order LP filters. The data must transferrered via the USB to a pc.

    In addition I need to measure 4 channels 10bit at 100Hz control 8 pwm outputs and control 3 stepper motors.

    Kind Regards,

    Cor

  • The data rate wouldn't be too high at all. This seems like a good solution. You might look at the ADS1015 for the 4-channel ADC, using the I2C port on the OMAP. The OMAP can do all the PWM control and such.

  • Hello Rick,

    Yes this is a nice component. I will look for it in more detail.

    regards,

    Cor

    p.s. Could you please provide me with the driver for the ADS1278, 8 channel synchronously sampling at 10kHz?

  • Here's the example project for the C6416, closest we have to anything for the OMAP platform.

    7115.ADS1278-DSK6416-CCS3v1.zip

  • Hello Rick,

    Thank you  very much for your help. The code looks straightforward for using. I realized that the 24bit ADC is quiet far away from the others, about 60 cm. So now I'm rethinking the architecture. Would it be possible to use the 24bit ADS1274 and use the 6x12 bit ADS8558 all synchronously sampling? In this way the signals can be sampled right at the sensor.

    Regards,

    Cor 

     

  • I don't see any reason why that couldn't be done.