[John Boxall] shows how to add four buttons using one ADC pin. The concept is nothing new. The buttons make up an R2R resistive ladder. When one of them is pressed, it completes the circuit for ...

the development team noticed that the ADC readings on a SAMD21-based board were off by a consistent 35 mV; expanding their tests to a number of different analog pins and SAMD21 boards, they saw ...