AVR and PIC microcontrollers

A microcontroller is a complete small computer on a single integrated circuit, combining a processor core, program and data memory, and input/output peripherals in one inexpensive package. Unlike a desktop processor it is designed to be embedded inside a product, reading sensors and switching outputs to control a device. Two of the most widely used families in hobby and educational electronics are Atmel's AVR and Microchip's PIC, both of which span a range of parts from tiny 8-pin chips to larger devices with many peripherals.

The AVR is an 8-bit microcontroller family with a RISC-style core, on-chip flash program memory and a set of peripherals such as timers, analogue-to-digital converters and serial interfaces. Its flash memory can be reprogrammed many times, which suits experimentation, and it became especially well known as the chip at the heart of many early Arduino boards. The PIC family from Microchip serves a similar role and is equally popular; older 8-bit parts such as the PIC16C84 introduced many builders to in-circuit programming. The long-established 8051 architecture, originally from Intel, is another classic core still produced by many makers.

Microcontrollers are programmed by writing code in C or assembly language, compiling or assembling it into machine code, and loading that code into the chip's program memory with a programmer or bootloader. Development typically uses a toolchain of compiler, assembler and a programming tool, and simulators allow code to be tested before it runs on real hardware. Once programmed, the microcontroller runs its stored program independently each time it is powered on.

Frequently asked questions

What is a microcontroller?

It is a single chip containing a processor, memory and input/output peripherals, designed to be embedded in a device and run a fixed program that controls it.

How do AVR and PIC differ from a desktop CPU?

They integrate the processor, memory and I/O on one low-cost chip aimed at embedded control, rather than being a high-performance processor needing external memory and support chips.

How is a microcontroller programmed?

Code written in C or assembly is compiled into machine code and loaded into the chip's flash memory using a programmer or bootloader, after which the chip runs that program on power-up.