mirror of
https://github.com/stianeikeland/go-rpio.git
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121 lines
4.2 KiB
Markdown
121 lines
4.2 KiB
Markdown
go-rpio
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=======
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Native GPIO-Gophers for your Pi!
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**Documentation:** [](https://godoc.org/github.com/stianeikeland/go-rpio)
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go-rpio is a Go library for accessing [GPIO](http://elinux.org/Rpi_Low-level_peripherals)-pins
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on the [Raspberry Pi](https://en.wikipedia.org/wiki/Raspberry_Pi).
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It requires no external c libraries such as
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[WiringPI](https://projects.drogon.net/raspberry-pi/wiringpi/) or [bcm2835](http://www.open.com.au/mikem/bcm2835).
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There's a tiny bit of additional information over at my [blog](https://blog.eikeland.se/2013/07/30/go-gpio-library-for-raspberry-pi/).
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## Releases ##
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- 1.0.0 - Supports original rpi A/B/B+
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- 2.0.0 - Adds support for rpi 2, by @akramer
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- 3.0.0 - Adds support for /dev/gpiomem, by @dotdoom
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- 4.0.0 - Adds support for PWM and Clock modes, by @Drahoslav7
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- 4.1.0 - Adds support for edge detection, by @Drahoslav7
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- 4.2.0 - Faster write and toggle of output pins, by @Drahoslav7
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- 4.3.0 - Adds support for SPI, by @Drahoslav7
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- 4.4.0 - Support for disabling interrupts (workaround for #35), by @Drahoslav7
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## Usage ##
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```go
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import "github.com/stianeikeland/go-rpio/v4"
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```
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If you're using an older go.mod incompatible you should instead use:
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```go
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import "github.com/stianeikeland/go-rpio"
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```
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Open memory range for GPIO access in /dev/mem
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```go
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err := rpio.Open()
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```
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Initialize a pin, run basic operations.
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Pin refers to the bcm2835 pin, not the physical pin on the raspberry pi header. Pin 10 here is exposed on the pin header as physical pin 19.
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```go
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pin := rpio.Pin(10)
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pin.Output() // Output mode
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pin.High() // Set pin High
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pin.Low() // Set pin Low
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pin.Toggle() // Toggle pin (Low -> High -> Low)
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pin.Input() // Input mode
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res := pin.Read() // Read state from pin (High / Low)
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pin.Mode(rpio.Output) // Alternative syntax
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pin.Write(rpio.High) // Alternative syntax
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```
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Pull up/down/off can be set using:
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```go
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pin.PullUp()
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pin.PullDown()
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pin.PullOff()
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pin.Pull(rpio.PullUp)
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```
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Unmap memory when done
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```go
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rpio.Close()
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```
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Also see example [examples/blinker/blinker.go](examples/blinker/blinker.go)
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### SPI
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#### setup/teardown
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- `rpio.SpiBegin(rpio.Spi0)` has to be called first before using any Spi func. It will change pin modes to `Spi` and initialize default setting.
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- `rpio.SpiEnd(rpio.Spi0)` should be called at the end, it will switch pin modes to `Input`.
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#### transferring data
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- `rpio.SpiTransmit(byte)` or `rpio.SpiTransmit(bytes...)` will transmit byte or bytes to slave.
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- `rpio.SpiReceive(n)` will return n bytes received from slave.
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- `rpio.SpiExchange(buffer)` will simultaneously transmit data from the buffer to slave and data from slave to the same buffer in full duplex way.
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#### settings
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- `rpio.SpiSpeed(hz)` will set transmit speed of SPI
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- `rpio.SpiChipSelect(n)` will select chip/slave (ce0, ce1, or ce2) to which transferring will be done
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- `rpio.SpiChipSelectPolarity(n, pol)` set chip select polarity (low enabled is used by default which usually works most of the time)
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- `rpio.SpiMode(cpol, cpha)` set clock/communication mode (=combination of clock polarity and clock phase; cpol=0, cpha=0 is used by default which usually works most of the time)
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## Other ##
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Currently, it supports basic functionality such as:
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- Pin Direction (Input / Output)
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- Write (High / Low)
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- Read (High / Low)
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- Pull (Up / Down / Off)
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- PWM (hardware, on supported pins)
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- Clock
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- Edge detection
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It works by memory-mapping the bcm2835 gpio range, and therefore require root/administrative-rights to run.
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## Using without root ##
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This library can utilize the new [/dev/gpiomem](https://github.com/raspberrypi/linux/pull/1112/files)
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memory range if available.
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You will probably need to upgrade to the latest kernel (or wait for the next raspbian release) if you're missing /dev/gpiomem. You will also need to add a `gpio` group, add your user to the group, and then set up udev rules. I would recommend using [create_gpio_user_permissions.py](https://github.com/waveform80/rpi-gpio/blob/master/create_gpio_user_permissions.py) if you're unsure how to do this.
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PWM modes will still require root.
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