Merge pull request #112 from fudger/master

Reformat readme.md for better readability.
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README.md
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# pigpio # pigpio
pigpio is a C library for the Raspberry which allows control of the pigpio is a C library for the Raspberry which allows control of the
General Purpose Input Outputs (GPIO). General Purpose Input Outputs (GPIO).
Features ## Features
sampling and time-stamping of GPIO 0-31 between 100,000 and 1,000,000 times per second. * Sampling and time-stamping of GPIO 0-31 between 100,000 and 1,000,000 times per second
* Provision of PWM on any number of the user GPIO simultaneously
* Provision of servo pulses on any number of the user GPIO simultaneously
* Callbacks when any of GPIO 0-31 change state (callbacks receive the time of the event
accurate to a few microseconds)
* Notifications via pipe when any of GPIO 0-31 change state
* Callbacks at timed intervals
* Reading/writing all of the GPIO in a bank (0-31, 32-53) as a single operation
* Individually setting GPIO modes, reading and writing
* Socket and pipe interfaces for the bulk of the functionality in addition to the
underlying C library calls
* Construction of arbitrary waveforms to give precise timing of output GPIO
level changes (accurate to a few microseconds)
* Software serial links, I2C, and SPI using any user GPIO
* Rudimentary permission control through the socket and pipe interfaces so users
can be prevented from "updating" inappropriate GPIO
* Creating and running scripts on the pigpio daemon
provision of PWM on any number of the user GPIO simultaneously. ## Interfaces
provision of servo pulses on any number of the user GPIO simultaneously.
callbacks when any of GPIO 0-31 change state (callbacks receive the time of the event
accurate to a few microseconds).
notifications via pipe when any of GPIO 0-31 change state.
callbacks at timed intervals.
reading/writing all of the GPIO in a bank (0-31, 32-53) as a single operation.
individually setting GPIO modes, reading and writing.
socket and pipe interfaces for the bulk of the functionality in addition to the
underlying C library calls.
the construction of arbitrary waveforms to give precise timing of output GPIO
level changes (accurate to a few microseconds).
software serial links, I2C, and SPI using any user GPIO.
rudimentary permission control through the socket and pipe interfaces so users
can be prevented from "updating" inappropriate GPIO.
creating and running scripts on the pigpio daemon.
Interfaces
The library provides a number of control interfaces The library provides a number of control interfaces
* the C function interface,
* the /dev/pigpio pipe interface,
* the socket interface (used by the pigs utility and the Python module).
the C function interface ## Utilities
the /dev/pigpio pipe interface A number of utility programs are provided:
* the pigpiod daemon,
* the Python module,
* the piscope digital waveform viewer,
* the pigs command line utility,
* the pig2vcd utility which converts notifications into the value change dump (VCD)
format (useful for viewing digital waveforms with GTKWave).
the socket interface (used by the pigs utility and the Python module) ## Example programs
Utilities See http://abyz.co.uk/rpi/pigpio/examples.html.
A number of utility programs are provided ## GPIO
the pigpiod daemon. ALL GPIO are identified by their Broadcom number. See http://elinux.org.
the Python module.
the piscope digital waveform viewer.
the pigs command line utility.
the pig2vcd utility which converts notifications into the value change dump (VCD)
format (useful for viewing digital waveforms with GTKWave).
Example programs
See http://abyz.co.uk/rpi/pigpio/examples.html
GPIO
ALL GPIO are identified by their Broadcom number. See elinux.org
There are 54 GPIO in total, arranged in two banks. There are 54 GPIO in total, arranged in two banks.
@ -69,31 +54,19 @@ Bank 1 contains GPIO 0-31. Bank 2 contains GPIO 32-54.
A user should only manipulate GPIO in bank 1. A user should only manipulate GPIO in bank 1.
There are at least three types of board. There are at least three types of board:
* Type 1
Type 1 * 26 pin header (P1)
* Hardware revision numbers of 2 and 3
26 pin header (P1). * User GPIO 0-1, 4, 7-11, 14-15, 17-18, 21-25
* Type 2
Hardware revision numbers of 2 and 3. * 26 pin header (P1) and an additional 8 pin header (P5)
* Hardware revision numbers of 4, 5, 6, and 15
User GPIO 0-1, 4, 7-11, 14-15, 17-18, 21-25. * User GPIO 2-4, 7-11, 14-15, 17-18, 22-25, 27-31
* Type 3
Type 2 * 40 pin expansion header (J8)
* Hardware revision numbers of 16 or greater
26 pin header (P1) and an additional 8 pin header (P5). * User GPIO 2-27 (0 and 1 are reserved)
Hardware revision numbers of 4, 5, 6, and 15.
User GPIO 2-4, 7-11, 14-15, 17-18, 22-25, 27-31.
Type 3
40 pin expansion header (J8).
Hardware revision numbers of 16 or greater.
User GPIO 2-27 (0 and 1 are reserved).
It is safe to read all the GPIO. If you try to write a system GPIO or change It is safe to read all the GPIO. If you try to write a system GPIO or change
its mode you can crash the Pi or corrupt the data on the SD card. its mode you can crash the Pi or corrupt the data on the SD card.