5 - Microcontroller inputs and outputs

Abstract

This chapter discusses single ended and differential digital and analog inputs and outputs, and their relation to microcontroller systems. There are two different types of input circuits used in data acquisition systems. One is single ended and the other is differential. Each of these circuits has their uses and their good and bad points. The advantage of single ended inputs is the same as analog inputs, it is only one channel per input. One difference between analog inputs and digital inputs is that digital inputs are more resistant to noise. The use of a differential two-channel input and the saturation of the optoisolator greatly reduce the chance of noise or high voltage. It is found that when measuring an analog input value, it is necessary to match the resolution of the microcontroller, the amount of information needed, and the ability of the sensor to supply the resolution. Keypad and liquid crystal display systems are the two examples of interfacing to a microcontroller.