Delta Sigma ADC demodulator/Sinc3 filter

G

GoWestBill

New member
I'm working on a circuit that uses a AMC3336 isolated ADC and need to convert the output to a reading of the applied input voltage. Sinc3 filter is mentioned in the data sheet and I am acquiring a C2000 dev board but in the meantime I wanted to see what a Teensy 4.1 would be capable of using its on chip resources. I don't need high throughput,something near DC is fine, just want to be able to apply a known voltage to the input and verify that the AMC3336 is reading it correctly.

Thanks in advance, Bill
 
Sinc3 filter appears to be something you would do in FPGA, so not sure if you can simply connect this device to T4.1 and have it do that in software.
 
20MHz is pretty fast for working with in software... Perhaps you could just about get a boxcar average to work on that as the first filter stage - depends how important anti-aliasing performance is to you. IIRC sinc3 does small cascaded boxcars and is rather more complex as a result.
 
What led me in this direction was the mention of DSP in the data sheet and here on pjrc as "DSP extension instructions". Looks like those are for audio frequencies. The data sheet for the AMC3336 has 9 MHz min clock but I just ran a test down to 1 KHz and the data looks valid - probably not meeting spec though. I will take a look at boxcar averaging and the DSP extension instructions. Oh, I've taken a look at the Teensy audio library but it looks like it only applies to 3.x boards, will it work with 4.1?
 
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