Microcontrollers-What's Out There
- 1 The Microdirectory - weblink
- 2 Families of Microcontrollers
- 2.1 PIC
- 2.2 Intel 8051 and variants
- 2.3 SuperH - Hitachi SH Family
- 2.4 ADuC812
- 2.5 Motorola 68HC11
- 3 Links
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.
- 8-bit ALU, Accumulator and Registers; hence it is an 8-bit microcontroller
- 8-bit data bus - It can access 8 bits of data in one operation
- 16-bit address bus - It can access 216 memory locations - 64 kB ( 65536 locations ) each of RAM and ROM
- On-chip RAM - 128 bytes ("Data Memory")
- On-chip ROM - 4 kB ("Program Memory")
- Four byte bi-directional input/output port
- UART (serial port)
- Two 16-bit Counter/timers
- Two-level interrupt priority
- Power saving mode
The SuperH (or SH) is brandname of a certain microcontroller and microprocessor architecture. The SuperH is fundamentally a 32-bit load/store RISC architecture found in a large number of embedded systems. SuperH is an embedded RISC developed for high cost-performance, miniaturization, and performance per unit of power consumption (MIPS/W). Product lines include a series with the SH-2 as the CPU core and on-chip large-capacity flash memory and peripheral functions such as timer, serial I/O, and AD converter, and a series with the SH-3 or SH-4 as the CPU core, which achieves high-speed data processing and is equipped with cache and MMU. Additionally, there is lineup of series with the SH2-DSP or SH3-DSP as the CPU core, which have full DSP functions and an emphasis on multimedia and communications processing. Currently available products also have lots of features, such as low power modes, low power consumption, and small size. Various versatile operating systems and development tools have been improved, allowing for more efficient development. See renesas.com.
- Speed (20 MIPS)
- Bits (32)
- RAM (8K)
- 16 bit timers (5)
- Interrupts (40)
- Power drain (100 mA)
- Pins to solder (100)
ADuC812 contains a high-speed 12-bit analogue to digital converter (ADC) with a sample & hold, and an 8-channel analogue multiplexer. The conversion rate can be controlled through software but is limited to about 200,000 conversions per second for full resolution. A 2.5 volt low drift voltage reference is integrated on-board. If desired an external voltage reference capable of overdriving the internal reference can be substituted. See mcjournal.com.
- 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