Microcontrollers-What's Out There

Families of Microcontrollers

PIC

General Description

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.

Comparisons

PIC vs. AVR - A comparison between PIC and AVR

Features

• 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

SH1 - Hitachi SH Family

• Speed (20 MIPS)
• Bits (32)
• RAM (8K)
• 16 bit timers (5)
• Interrupts (40)
• Power drain (100 mA)
• Pins to solder (100)

ADuC812

• Good for data collection, smart sensor type application
• Fast (5 us) 8 channel, 12 bit ADC
• Hardware UART
• Flash
• CISC
• 1.25 MIPS max

68HC11

• 8 channel, 8 bit ADC
• 20K program, 1K RAM
• 5 16-bit timers
• 38 I/O pins
• UART
• 24 bit external memory space
• But: 3 MHz clock

Links

• 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