EE 308 Spring 2010Microcontroller ArchitecturesThings to Consider• Performance vs. Cost– Speed (instructions/second)– Precision (8, 16, 32 or 64 bits, fixed or floating point)– Princeton or Harvard Architecture– RISC or CISC?∗ RISC: Reduced Instruction Set Computer· Very few instructions (8-bit PIC uses 33 instructions)· Each instruction takes one cycle to execute· Each instruction takes one word of memory· Reduces hardware size, increases software size· Easier to implement pipelines, etc.∗ CISC: Complex Instruction Set Computer· Larger number of more specialized instructions· Increases hardware size, reduces software size• Voltage• Peripherals– A/D converter (number of bits)– COM ports (how many, what type – SCI, SPI I2C)– USB– Ethernet– Timers– Specialized items∗ PWM∗ Media control (Compact Flash, Secure Digital cards)∗ Many others• Memory– Address bus size– RAM– EEPROM– Flash EEPROM• Special Requirements– Low power for battery applications– Radiation hardened for space applications– Temperature range1EE 308 Spring 2010• Development Tools– Software Tools∗ Assembler∗ C Compiler∗ IDE– Hardware tools∗ Evaluation boards∗ In Circuit Emulators∗ Background Debug Mode• Familiarity– Different lines from same manufacturer often have similar programming modelsand instruction forms– For example, consider writing the byte $AA to address held in the X register:∗ Motorola: movb #$AA, 0,X∗ Intel: mov [ECX] 0AAH– Consider the way the 16-bit $1234 number is stored in memory location $20001. Motorola: $12 is stored in address $2000,$34 is stored in address $20012. Intel: $34 is stored in address $2000,$12 is stored in address $20012EE 308 Spring 2010Freescale (Motorola) Microcontrollers• HC08 (8 bit)– $1.00 each– 8 pins to 80 pins– 128 bytes to 2 KB RAM– 1.5 KB to 7680 KB Flash EEPROM– 2 MHz to 8 MHz clock– Lots of different peripherals• HCS08 (8 bit)– $2.00 each (and higher)– 8 pins to 64 pins– 512 bytes to 4 KB RAM– 4 KB to 60 KB Flash EEPROM– 8 MHz or 20 MHz clock– Lots of different peripherals• HCS12 (16 bit)– $10.00 each (and higher)– 48 pins to 112 pins– 2 KB to 12 KB RAM– 1 KB to 4 KB EEPROM– 32 KB to 512 KB Flash EEPROM3EE 308 Spring 2010– 25 MHz to 50 MHz clock– Lots of different peripherals• S12X (16 bit)– $20.00 each (and higher)– 48 pins to 112 pins– 4 KB to 12 KB RAM– 1 KB to 4 KB EEPROM– 32 KB to 512 KB Flash EEPROM– 25 MHz clock– Lots of different peripherals• 56800 DSP (32 bit)– $7.00 each (and higher)– 48 pins to 112 pins– 4 KB to 32 KB RAM– 16 KB to 512 KB Flash EEPROM– 32 MHz to 120 MHz clock– Specialized for such things as audio processing• MAC (32 bit)– $20.00 each (and higher)– 32-bit upgrade of 9S12 line for automotive applications– 112 pins to 208 pins– 16 KB to 48 KB RAM– 384 KB to 1024 KB Flash EEPROM– 40 MHz to 50 MHz clock– Specialized for such things as audio processing• ColdFire (32 bit)– $40.00 each (and higher)– 144 pins to 256 pins– 16 MHz to 266 MHz clock• Power PC (32 bit)– $40.00 each (and higher)– 272 pins to 388 pins– 26 KB to 32 KB RAM– 448 KB to 1024 KB Flash EEPROM– 40 MHz to 66 MHz clock4EE 308 Spring 2010Other Manufacturers• Low end (8 bit)– PIC from Microchip∗ Very inexpensive ($0.50)∗ Low pin count (6 to 100)∗ Often small memory (16 bytes RAM, 128 bytes ROM)∗ RISC– 8051 (Originally Intel, now National, TI)– Z8 (Zilog – similar to 8051)• Mid-Range (16 bits)– Z80 and Z180 from Rabbit• High End (32 bit)– ARM - licensed to Intel, TI, many others– MIPS - licensed to Hitachi• Soft Core– Altera NIOS∗ Can customize to meet needs∗ Speed vs. size (number of logic gates)∗ 16-bit or 32-bit∗ Fixed point or floating point∗ Memory management or no me mory management∗ Can build specialized instructions to increase performance– Xilinx ARM (soft core or hard
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