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AMC1203EVM: Digital Output interfacing with MSP430FR5994 Microcontroller

Part Number: AMC1203EVM
Other Parts Discussed in Thread: MSP430FR5994, ADS1203, ADS1202, AMC1203, AMC1200, AMC1100


I am working on a constant current power supply in which i need to measure output current. The current shunt resistor will drop around 50-60 millivolt. I need to provide this exact voltage drop value to microcontroller MSP430FR5994. I was thinking of using AMC1203EVM for the same, since it has 250 mVolt input range and good enough resolution for precision current measurement. However, i don't know whether i will be able to directly interface the digital outputs of AMC1203EVM with microcontroller or not.

I have no practical experience working with ADCs. So, i don't know whether i can interface MDAT and MCLK modulator outputs directly with microcontroller or not.

If not, can you please suggest a solution for the above stated application? Can something like ADS1202/ ADS1203 be a better option?


Hard Patel

  • Hi Hard,

    The MSP430FR5994 does not accommodate the MDAT and MCLK of the AMC1203. Since you are also asking about the ADS1202 or ADS1203, is it safe to assume you do not need any sort of voltage isolation?
  • Hi Tom,

    Yes your assumption is correct. I do not need voltage isolation specifically. It is just an advantage. Circuit will work without isolation also. I had chosen AMC1203 just because of the 250 milivolt analog input range.

    One more thing i would like to mention is that, i am interfacing with MSP430FR5994 LaunchPad. I have to somehow read the current values via ADC voltage drop into my MSP Launchpad.

    Can AMC1203EVM be interfaced in any way with MSP430FR5994 Launchpad? If not, kindly suggest some other way of interfacing or some other hardware. Thanks.

    Hard Patel

  • Hard,

    The AMC1203 is a digital modulator - the output is a digital bitstream that has to be put through a digital filter to get any meaningful data from it.  Some of the MSP430 devices (those with the SD24B module) have the ability to accomodate the bitstream and do the digital filtering, but the MSP430FG5994 does not have that peripheral.  That being said, the ADC12_B found on the MSP430FG5994 does have the ability to accomodate a differential input signal.  Take a look at the AMC1100 or the AMC1200, which are differential output amplifiers.  This would give you an analog output that, when operated at 3.3V on VDD2, should work with your launchpad and the ADC input to the MSP430.

  • Thanks a lot Tom,

    Your suggestion is perfect for me.

    I will use AMC1200 which will amplify my 50-60 milivolt DC signal with gain of 8 and then i can give the differential output of AMC1200 to two ADC pins of MSP430FR5994, which will give me digital readings.

    Thanks again
    Hard Patel
  • Just be careful to verify which ADC channels are on the LaunchPad. The pairs in differential mode are 0-1, 2-3, 4-5 etc. Details are in the MSP430 data sheets and LP user manuels.
  • However, if due to some limitation in launchpad pin availability, i am not able to connect AMC1200 output in differential pins, can i connect AMC1200 output in any 2 pins and read both voltages differently. And subtract the 1.29 volts (due to 3.3 volt on VDD2) programmatically?

    Or is that a bad idea?
  • Hi Hard,

    You'd really want to use a differential pair, it looks like P1.2 and P1.3 (A2 and A3) as well as P1.4 and P1.5 (A4 and A5) are available on J1 and J3 respectively. Either one of those channel pairs should work.