CSCI 255 — Embedded Systems

The Textbook

Read Section 8.6 of the textbook.

• Memory and I/O, pp 77–86

PIC 32 reference suvey

• Datasheets (wiring)
  • PIC32MX1XX/2XX datasheet
  • PIC32 Family Reference Manual (Documentation → Reference Manual)
  • PIC12LF1822 datasheet
• Programming (downloading)
  • Microstick II
  • PICKit 3 programmer
• I/O (programming)
  • PIC32 Family Reference Manual, Sect. 12 I/O Ports
  • PIC32 Ports Overview
  • 8-bit PIC peripherals

More about the PIC32 MX

• PIC32MX1XX/2XX 28/36/44-PIN datasheet (again)
  • Pin layout — page 4, Table 3
  • Minimal setup — page 28, Figure 2-1
  • Programming setup — page 28, Figure 2-2
  • Memory organization — page 39, Table 4-2
  • SFR memory locations — page 44, Table 4-1
  • Oscillator control — page 74, Figure 8-1
  • GPIO Port structure — page 127, Figure 11-1
• MIPS® Architecture For Programmers Volume II-A: The MIPS32® Instruction Set

“Building” a computer on a breadboard

• the really hard way
• 8 bit spaghetti
• Arduino on a breadboard
• Arduino Tiny AVR programmer
• Arduino in Altoid
• 

GPIO interfaces

In general, there are at least three collections of registers to control GPIO.

• One sets the direction — input or output: TRISp of DDRp
• One writes the pin — 0 or 1: LATp or PORTp
• One reads the pin — 0 or 1: PORTp or PINp

GPIO in C

Take a look at the first part of the lab on PIC32 GPIO to see how C is used for GPIO. (You can also use assembly code!)

GPIO in Arduino

• pinMode()
• digitalWrite()
• digitalRead()

GPIO on the Raspberry Pi

• easiest — Python (RPi.GPIO) API
• Linux-est — GPIO Sysfs

Looking at some source — Arduino

• Wiring site
• Wiring at Wikipedia
• Github
  • Arduino
  • Arduino AVR
  • main
  • wiring.c — timing and delay
  • wiring_digital.c — digital I/O
  • port stuff
    • Arduino.h — lots of constants
    • pins_arduino.h — pin definitions