Library to access the GPIO pins on a Raspberry Pi from Haskell. Works with all Raspberry Pi versions up to and including v4.

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HPi is a small library to access the GPIO pins on a Raspberry Pi from Haskell. It also includes some functions to use the I2C, SPI, and PWM functionality of the Raspberry Pi, see the haddock documentation for details. It is constructed as a FFI wrapper around the bcm2835 library, which is written in C. Because this library accesses the GPIO pins directly via a memory map, it should be faster than libraries which access the GPIO pins via the /sys/class/gpio interface.

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In order to compile programs including this library, you will need to have the bcm2835 library installed. It can be found at http://airspayce.com/mikem/bcm2835/index.html. When performing the cabal install for HPi you may need to pass the --extra-lib-dirs and --extra-include-dirs flags if you have installed bcm2835 at a non-standard path. This library has been tested to work with bcm2835 version 1.63. Note that you cannot access the memory map without root privileges, programs should be run with sudo.

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Questions, bug reports and feature requests are more than welcome!