mirror of https://github.com/joan2937/pigpio
98 lines
2.5 KiB
Markdown
98 lines
2.5 KiB
Markdown
# pigpio
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pigpio is a C library for the Raspberry which allows control of the
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general purpose input outputs (gpios).
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Features
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sampling and time-stamping of gpios 0-31 between 100,000 and 1,000,000 times per second.
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provision of PWM on any number of the user gpios simultaneously.
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provision of servo pulses on any number of the user gpios simultaneously.
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callbacks when any of gpios 0-31 change state (callbacks receive the time of the event
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accurate to a few microseconds).
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notifications via pipe when any of gpios 0-31 change state.
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callbacks at timed intervals.
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reading/writing all of the gpios in a bank (0-31, 32-53) as a single operation.
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individually setting gpio modes, reading and writing.
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socket and pipe interfaces for the bulk of the functionality in addition to the
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underlying C library calls.
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the construction of arbitrary waveforms to give precise timing of output gpio
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level changes (accurate to a few microseconds).
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software serial links using any user gpio.
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rudimentary permission control through the socket and pipe interfaces so users
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can be prevented from "updating" inappropriate gpios.
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creating and running scripts on the pigpio daemon.
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Interfaces
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The library provides a number of control interfaces
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the C function interface
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the /dev/pigpio pipe interface
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the socket interface (used by the pigs utility and the Python module)
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Utilities
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A number of utility programs are provided
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the pigpiod daemon.
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the Python module.
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the pigs command line utility.
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the pig2vcd utility which converts notifications into the value change dump (VCD)
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format (useful for viewing digital waveforms with GTKWave).
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gpios
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ALL gpios are identified by their Broadcom number. See elinux.org
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There are 54 gpios in total, arranged in two banks.
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Bank 1 contains gpios 0-31. Bank 2 contains gpios 32-54.
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A user should only manipulate gpios in bank 1.
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There are at least three types of board.
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Type 1
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26 pin header (P1).
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Hardware revision numbers of 2 and 3.
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User gpios 0-1, 4, 7-11, 14-15, 17-18, 21-25.
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Type 2
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26 pin header (P1) and an additional 8 pin header (P5).
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Hardware revision numbers of 4, 5, 6, and 15.
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User gpios 2-4, 7-11, 14-15, 17-18, 22-25, 27-31.
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Type 3
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40 pin expansion header (J8).
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Hardware revision numbers of 16 or greater.
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User gpios 2-27 (0 and 1 are reserved).
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It is safe to read all the gpios. If you try to write a system gpio or change
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its mode you can crash the Pi or corrupt the data on the SD card.
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