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ADS1230: make low cost Weigh Scale

Natesh kannan S
Intellectual 270 points
Part Number: ADS1230
Other Parts Discussed in Thread: ADS1231

hi friends

i just think to make a low cost weigh scale with ads1230 with cc3220 

please clear my doubts

1.it's Communicate with SPI Communication. is it possible to get ADC output depend upon the load.

2. i put 5kg load before power on my device. now power on the device is it shows load is 5kg or 0kg, incase this shows 0kg how to get my corresponding load value (applied load before power on)

3.the example code is available for this or not.

thanks in advance.

with regards

kannannatesh

  • 0
    TI__Guru** 113765 points

    Hi Natesh,

    The ADS1230 is an analog-to-digital converter (ADC) that converts a voltage input to a digital code.  It does not make a direct conversion to weight.  The weight conversion is accomplished in your firmware code.  To get the best performance with the lowest noise, you make the measurement ratiometric where the excitation voltage and reference voltage are the same.  The ratiometric measurement will cancel common noise and drift of the excitation/reference source.

    The output of the ADC is a digital representation of the input voltage.  In the case of a load cell, yes the ADC output directly corresponds to the load placed on the load cell.

    Placing the load on the load cell prior to applying power should have no negative affect.  You would still see the expected digital value, although there may be some offset (that can be calibrated out using the device offset calibration) or analog settling while caps charge.

    You may want to take a look at the ADS1231 which has a low-side switch to conserve sensor power by breaking the excitation current path.  This allows the ADS1231 to be placed in a very low power state while still keeping the analog supply active.  This removes any issues with powering up/down/up the device while still conserving power.

    At this time I do not have good example code.  I am working on some new code, but can't give a firm time when it will be available.  The ADS1230 is mostly pin controlled with the SPI being in the form of 2-wire.  SCLK and MISO is all that is required using a Mode 1 SPI configuration (SCLK dwells low and data latched on the falling SCLK edge).  You would initiate the SCLKs by sending three bytes to the micro buffer and reading the RX buffer after each byte is transmitted.  The conversion data is sent MSB first.  The ADS1230 datasheet covers the communication.

    The other piece of code would be the conversion of the digital code to weight.  The process and calculation is covered in the user's guide for the ADS1230REF in section 2.1.1 on page 8:

    http://www.ti.com/lit/ug/sbau125a/sbau125a.pdf

    Best regards,

    Bob B