What is Positive and Negative Mux input in ADC

Question

I am trying to understand the use of Positive and Negative Mux input in ADC, I have recenlty bought Atsamd21-Xplained board from Atmel and trying to get multiple pins ADC using ASF4 and with Atmel Start. While i was exploring the concept of ADC on Samd21,i came up with Positive Mux Input Selection and Negative Mux Input Selection drop down menus while configuring ADC in Atmel Start

I have came with the information that these are used for inputting into ADC. But what is the purpose.?Why it's used.?How can i configure for a single pin ADC and Multiple.? My other question is : How can i read Analog values from multiple ADC pins on ATsamd21 with ASF4 and Atmel Start.

Thank you.

Answer 1

This is a differential input ADC. It reads the voltage difference between the two input pins.

Typically, for a single input pin application, you would use the positive input pin as your input, and take the negative input pin to ground.

Read the data sheet carefully for the range of input voltages that each pin can be taken to. It may be that ground is not within the common mode range for that pin, in which case you would have to take it to some reference voltage that was in the required range.