Microcontrollers-What's Out There
The Microdirectory is a fantastic online directory of microprocessors and microcontrollers which is updated annually. Check out this page for past microdirectories: http://www.edn.com/info/1340009098.html. This page will help quite a bit in your search for the perfect microcontroller.
Families of Microcontrollers
The Microchip PIC microcontrollers were perhaps the first that were marketed to the hobbyist and student community, one of the first microcontrollers to be offered in a relatively small package (18 pin DIP) and one of the first to implement flash or eeprom program memory (in the PIC16C84 in 1993)
Architecture: harvard, accumulator based (mostly) Package sizes: 6, 8, 14, 18, 20, 28, 40, ... 100 Program memory size: 256 words (12bit words = one instruction) to 256k bytes (2 bytes=1 instruction) Data RAM: 16 to ~3900 bytes (4096 byte address space, shared with peripheral registers.) Special features: EEPROM, 20mA output drive, several "sub-architectures"
Flash memory based PIC microcontrollers curently range from vanishingly small 6-pin chips in SOT23 packages to 100pin TQFPs. The basic architecture has been extended to chips with 16bit ALUs and integral DSP functionality.
Microchip has a liberal sample policy and chips are widely available from many vendors.
PIC vs. AVR - A comparison between PIC and AVR
- Excellent general purpose chips
- 18 - 28 pin packages (down to 8) with 14-22 I/O
- ADC available, usually 4 channels, 8 bits
- Max. 5 MIPS
- Hardware UART on heavier chips
- No external addressing
Intel invented the 8051 architecture a long time ago, and garnered some hobbyist interest with the 8052BASIC chip, which contained a basic interpretter in masked ROM and allowed one to build a very small BASIC based computer. Since then the architecture has been licensed and/or stolen by MANY vendors, and good things have happened to it. It's been shrunk, expanded, speeded up, made lower power, had peripherals added, increased memory, flash and eeprom (and even ferromagnetic ram) added. Most variants are somewhat harder to find than PIC or AVR chips.
- Speed (20 MIPS)
- Bits (32)
- RAM (8K)
- 16 bit timers (5)
- Interrupts (40)
- Power drain (100 mA)
- Pins to solder (100)
- Good for data collection, smart sensor type application
- Fast (5 us) 8 channel, 12 bit ADC
- Hardware UART
- 1.25 MIPS max
- 8 channel, 8 bit ADC
- 20K program, 1K RAM
- 5 16-bit timers
- 38 I/O pins
- 24 bit external memory space
- But: 3 MHz clock
- Wikipedia article: http://en.wikipedia.org/wiki/Microcontroller
- Microcontroller Interfacing Laboratory at North Dakota State: http://www.ece.ndsu.nodak.edu/~tareski/pub/sccs98.htm
- Selecting Microcontrollers - Blog: http://www.8051projects.info/blogs.asp?view=plink&id=132
- Selecting Microcontrollers - Evil Mad Scientist!: http://www.evilmadscientist.com/article.php/mcus
- MIT Microcontroller Overview Lecture Notes - http://www.media.mit.edu/physics/pedagogy/fab/ucntrl/fabmicronotes.html