Changing the Thermocouple IC

[Mikefly123]

Current Implementation

Right now the thermocouple on the battery board is a AD8495 feeding into an ADS1015 I2C ADC. This has been working fine for us, but on the V3b spin of the boards the thermocouple has become problematic (see #6 for more).

Rationale for Change

Our existing implementation of the thermocouple would make more sense if we were planning to have multiple thermocouple inputs, since up to four inputs can be fed into the ADS1015 and read individually. In the entire history of the PROVES Kit though, we have not had the need to have more than one thermocouple. Additionally, even if we wanted more than one thermocouple, the battery board is now so crowded there would be no room for the circuit. Therefore, if we wanted more than one couple we would need an expansion board anyways.

If we changed over to an all in one thermocouple IC it could significantly reduce the board's overall part count and slightly compact the layout.

[Mikefly123]

Proposed Change

I'm thinking about swapping everything over to a MAX31856 thermocouple IC. This is supported by Adafruit through their Universal Thermocouple Board. See the data sheet here.

The schematic gets significantly simpler when using this IC instead of the other scheme!