Introduction to the PIC microcontroller

This chapter presents an introduction to the PIC microcontroller. A microcontroller is a computer control system on a single chip. It has many electronic circuits built into it, which can decode written instructions and convert them to electrical signals. The microcontroller will then step through these instructions and execute them one by one. The instructions we program into our microcontroller work by moving and manipulating data in memory locations known as user files and registers. PIC Microcontrollers are 8 bit micros, which means that the memory locations, the user files, and registers are made up of 8 binary digits. In order to step through the instructions the microcontroller needs a clock frequency to orchestrate the movement of the data around its electronic circuits. This can be provided by two capacitors and a crystal or by an internal oscillator circuit. The higher the clock frequency, the quicker the micro will finish one task and start another. It is found that the crystal and capacitors connected to pins 15 and 16 of the 16F84 produce the clock pulses that are required to step the microcontroller through the program and provide the timing pulses.