Raspberry Pi GPIO

SoutheastCon paper
BCM2385 ARM Peripherals
- Address Map (pp 5)
- Chapter 3 (pp 28–37), BSC (Broadcom Serial Controller) or I²C
- Chapter 6 (pp 89–108), General Purpose I/O
- Chapter 9 (pp 138–147), Pulse Width Modulation
- I²C
The pinout — Physical vs GPIO
- RPi Low-level peripherals
GPIO on Linux — a tale of many kernel interfaces
- The sysfs interface
  - Deprecated ABI documentation
    - No input with pullup?
  - /sys/class/gpio
  - ls -i /sys/class
  - mount | grep sysfs
- The dangerous /dev/mem hack
  - Memory mapping /dev/mem hack
- The safer /dev/gpiomem solution
  - Kernel source for the entire driver
  - mmap system call
- Character device with ioctl
  - /dev/gpiochipN
  - Character device documentation
  - ioctl based ABI
- Writing a device driver — Yikes!
- The ultimate quide
GPIO on Linux — a tale of many programming interfaces
- sysfs and the shell
- The dangerous /dev/mem hack
  - There is no excuse for doing this...
- The safer /dev/gpiomem solution
  - pigpio library
    - dpkg --listfiles pigpio
  - RPi.GPIO interface
- Character device with ioctl
  - lsgpio source
  - Presentations from another Linus

Things to do

Try having the button toggle the LED off and on. You may need to do a little switch debouncing. (Sleeping for 0.1 seconds should be OK.)

So many choices

GPIO libraries

GPIO tutorials

Our first attempt

2014 Pinkie Pie