qmk_firmware/docs/internals_gpio_control.md
Jack Humbert 15f6278aa6
Add support for Atmega32A to pin declarations and universal matrix (#4015)
* add computed pins from mcu type

* update for atmega32a

* doc typo

* add atmega16 chips, link to references

* remove avr include from config

* exclude assembler in config.h includes

* consolodate options, add 646

* fix typo in pindef
2018-11-02 12:31:40 -04:00

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# GPIO Control
QMK has a GPIO control abstraction layer which is micro-controller agnostic. This is done to allow easy access to pin control across different platforms.
## Functions
The following functions can provide basic control of GPIOs and are found in `quantum/quantum.h`.
|Function |Description |
|----------------------|------------------------------------------------------------------|
|`setPinInput(pin)` |Set pin as input with high impedance (High-Z) |
|`setPinInputHigh(pin)`|Set pin as input with build in pull-up |
|`setPinInputLow(pin)` |Set pin as input with build in pull-down (Supported only on STM32)|
|`setPinOutput(pin)` |Set pin as output |
|`writePinHigh(pin)` |Set pin level as high, assuming it is an output |
|`writePinLow(pin)` |Set pin level as low, assuming it is an output |
|`writePin(pin, level)`|Set pin level, assuming it is an output |
|`readPin(pin)` |Returns the level of the pin |
## Advance settings
Each micro-controller can have multiple advance settings regarding its GPIO. This abstraction layer does not limit the use of architecture specific functions. Advance users should consult the datasheet of there desired device and include any needed libraries. For AVR the standard avr/io.h library is used and for STM32 the Chibios [PAL library](http://chibios.sourceforge.net/docs3/hal/group___p_a_l.html) is used.