CS 273: PIC Microprocessors

PIC 12F508

• Datasheet (PDF)

Notes:

• Very broad line with probably hundreds of different devices available. Some have built-in USB interfaces, some have built-in A/D, some have built-in ethernet, some have built-in CAN, etc.
• 12F508 is near bottom of the line. Bottom-devices (10F200) are six-pin package (power, ground, 1 in, 3 io); this is 8-pin package (power, ground, 1 in, 5 io)
• True Harvard architecture
• 12-bit instructions
• RISC instruction set
  • all instructions same size
  • all instructions except branches 1 cycle; branches take 2
• No real notion of "memory" as opposed to registers, but memory-mapped anyway

Things to look at in datasheet:

• P1: overview
• P12: block diagram
• P17: program memory organization (mention no real interrupts)
• P19: data "memory" organization
• P42: CONFIG word
• P22: STATUS register
• P24: OPTION register
• P58: instruction set
  • Very, very limited arithmetic. But rich set of bit-twiddling.
  • No real notion of instruction+addressing mode. Uses different instruction mnemonic for different mode
  • Oddball conditional branches
  • Very weird in that writing to some registers requires special instructions.