• Comparing values
• Multiple word arithmetic
  • Instructions: addc, subb, cpb
  • Carry is C
  • Borrow is -C
  • Z is sticky and can only be cleared
• Tens complement — Wikipedia or YouTube
• Storing large constant arrays
  • Data memory size is much smaller than program memory size
    • In the PIC24HJ64GP502: 128KB of program memory & 8KB of data memory
  • But data addresses are 16 bits long 64KB to be accessed
    • Allow upper 32KB of data address space to be mapped to program memory
    • See page 52 of PIC24HJ64GP502 data sheet
• Initialize global data by copying from program memory
• Multiplication
  • Two registers can be muliiplied and stored into a two successive registers
  • Signed and unsigned multiplication requires different instructions
  • A 17⨯17 bit hardware multiplier is used.
• Division
  • Requires use of REPEAT instruction
  • The DIV instruction must be executed 18 times
  • Requires 19 clock cycles, but may be interrupted
  • Uses a non-restoring algorithm
• C Preprocessor magic
  • MSU ECE 3724 notes — pp. 5-9
• PIC processor restart
  • MSU ECE 3724 notes — pp. 25-26
• Making better music
  • With analog
    • filter cutoff
    • Fourier series for square wave
    • RC delay
  • With digital
    • DAC
    • PWM
    • PDM