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What is the ADC converter to be used with BeagleBoard-X15 to transform 0-10V into 0-1.8V?

pascal sim
Prodigy 50 points
Other Parts Discussed in Thread: BEAGLEBOARD-X15, AM5728, PCA9306, ADS124S08

Hi,

i want to measure temperature in order to control heater.

I have three compartiments in my machines where i want to control heater.

i have three PT100 temperature sensor with output: 0-10V

The BeagleBoard-X15 can only receive signal 0-1.8V

1-Can BeagleBoard-X15 retrieve temperature signal from three sensor in the same time?

2-Which ADC shoud i use? can someone give me the part number please.

Thank you

  • 0
    TI__Guru**** 161600 points

    Hi,

    1. Yes, the device should be able to work with three sensors at once, if they are connected to different interface instances.

    2. There is no particular recommendation for this. Basically AM5728 could work with most of the available ADCs on the market, I'd suggest looking at devices that use serial interfaces (SPI, I2C, etc.) to transfer data to the SoC. Also it would be easier for your future work to choose a device that already has a driver (depending on what OS are you going to use in your application: Linux or RTOS).

    Best Regards,
    Yordan

  • 0 in reply to Yordan Kovachev
    Prodigy 50 points

    Thank you Yordan,

    i will use linux as OS with BeagleBoard-X15.

    And i did not find another device with driver already integrated maybe there ar so many byt with my knowlegde i did not find.

    But BBX-15 has I2C (serial interface) which seems good for me.

    I did find this card 8-Channel 0-10V Analog to Digital Converter with I2C Interface

    and PCA9306 I2C Data and Power Level Shifter .3VDC to 5VDC Bus Handler I2C Mini Module

    at

  • 0
    TI__Guru* 97465 points
    Pascal,


    In your first post, you mention that the PT100 has a range of 0-10V. The RTD is a resistance element and you measure the resistance to get a measurement of the temperature. Because of this, you can set the measurement range however you want and aren't bound to a 0V to 10V measurement.

    There are many ways to measure an RTD, but the most common would be to use an excitation current source and make a ratiometric measurement using a precision resistor as a reference. There are several different ways to construct this depending on the number of RTD leads.

    First, you can find more information about making an RTD measurement with the following app note:

    www.ti.com/.../sbaa275.pdf

    If you are using a two-, three-, or four-wire RTD, you should be able to find a topology to help you measure multiple RTDs. Look through the app note and then post back with what kind of circuit you want to put together. Depending on the precision you need, I would guess that the ADS124S08 would be a good device to use. (I would note that it uses an SPI type communication though).


    Joseph Wu