arduino due interfacing with AD7705

Dear friends,


 I am in big trouble, I designed a sensor system by interfacing AD7705 ADC with ATMGA328P-AU. All the library files I downloaded from (www.kerrywong.com/.../ )
And it is working fine.

   Now I want to change the controller to 32 bit SAM3x8e. The old library we used for AD7705 is not supporting. I am new with this controller, is there anyone to help me to find the solution. Can you suggest what change I should make in the old library? library file which is using is given below please go through it 

github.com/.../AD770X

hoping someone will help me .....................

Thank you..............



tags and product # corrected
[edited by: lallison at 2:04 PM (GMT 0) on 1 Oct 2019]
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  • HI,

    Thermopile application also can use this particular part number (AD7124)?. The thermopile output millivolt is 0-4.7mv only. So can we directly connect to ADC or needed any amplification network. Datasheet for thermopile is given below. please go through it.Thermopile.pdf

  • 0
    •  Analog Employees 
    on Oct 22, 2019 3:18 AM over 1 year ago in reply to heatcn

    Hi,

    Yes, AD7124 establishes the highest degree of signal chain integration, it consist of an on-chip low noise PGA that can amplify the small signal from your thermopile with a gain programmable from 1 to 128, thus allowing direct interface with the sensor. Upon looking at the attached sensor, looks like it has two sensors in one package. One for your thermopile and the other for cold junction. The thermopile can be connected to one channel (AIN0, AIN1) just like a thermocouple as shown on the figure below. AIN0 and AIN1 are configured as fully differential and since it is floating you have to enable the Vbias voltage generator enabled on AIN0 and biases the thermopile to mid supply. For this measurement you can use the internal 2.5V as your reference.

    For your cold junction, since the NTC looks like single ended you can just use another channel (AIN2, AIN3) and configured it as single ended, since you will set the Gain=1 for this measurement you have to disable the negative analog input buffer to meet the required common mode. For this measurement you can also use the internal 2.5V. For this, you can just treat the circuit as voltage divider, measure the voltage across the thermistor, use this to calculate the current and then get the thermistor resistance from these values.

    In terms of speed and noise performance, you can either use sinc4 filter, full power mode with an ODR of 50sps. This condition gives you the best performance in relation to speed and noise. Another option is to configure with post filter at full power mode with 25sps. This will give you simultaneous 50Hz and 60Hz rejection allowing to trade off the settling time and rejection.

    Thanks,

    Jellenie