Differential ADC On the Spark Core?

Hardware
1

Just starting to investigate the capabilities of the Spark core to integrate into a project. I’m digging through the datasheets and it doesn’t appear that the ADC on the STM32F10X is capable of anything but single ended measurements.
Am I correct in this assumption?

Thanks,
Jim

2

Hi @jag304

Here’s the app note for the ADC modes.

I believe the Spark currently uses Dual slow interleaved mode with a software averaging filter of 20 samples. The input of the ADC is not buffered and so the input impedance varies with the sample-rate you select, but is never what you would call high-impedance–40k ohm into 3.3V divided by 2 is good rough estimate.

I don’t see any differential input possibilities either but there is not a lot of room at 3.3V.

Maybe if you tell us more about what you are trying to do, we can help more.

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3

Thanks for the speedy response. I was hoping to do thermocouple measurements without much additional analog overhead, but I may not be able to avoid it.

4

I like the Maxim parts for this but the Analog Devices parts are fine as well:

https://www.sparkfun.com/products/306 (5V only)

Good luck!

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