A family of integrated circuits that contain all the sub-systems needed to make programmable control systems.
AVR
Atmel manufactures a large family of Programmable Integrated Circuits (PICs).
Here is a PDF file about the Atmel AVR
AVR might stand for Advanced Virtual RISC.
- Advanced - well you wouldn't want to sell something that wasn't advanced.
- Virtual - Simultates the real thing (possibly better that the real thing)
- RISC - Reduced Instruction Set Computing (simpler, faster and more reliable than older technologies)
AVR might also stand for the company's founders: Alf and Vegard.
PIC Chips
These chips have an extra instruction bus. This allows instructions to be fetched at the same time as the data. This makes the processing faster. This is known as the Harvard Architecture.
The chips are useful because ...
- low cost
- simple to use
- easy to interface to sensors and control actuators
- versatile
- can be re-programmed for use in many different domestic and industrial control applications
The chips benefit society because ...
- domestic appliances become cheaper
- domestic appliances become more useful and versatile (programmable bread maker, washing machine, clock radio, VCR, etc)
- provide more information to the user (electricity meters can now display power usage in a visible location (not under the stairs). This allows users to save energy, money and the planet).
- car engine management processors save fuel, carbon emissions and reduce engine wear.
The chips contain ...
- processor
- data bus, instruction bus, address bus and control bus
- ROM - Memory that contains code that never changes.
- Flash RAM (retains its data with the power off but can be re-programmed)
- RAM - used for temporary storage
- Input/Output (I/O)
- Some chips have DAC and ADC circuits
Here is a simplified summary of the PIC chip.
You can download the data sheet for the PIC16F87xA range from microchip.com. The architecture diagram below is quoted from this sheet.
