QMK has a GPIO control abstraction layer which is microcontroller agnostic. This is done to allow easy access to pin control across different platforms.
## Functions :id=functions
The following functions provide basic control of GPIOs and are found in `platforms/<platform>/gpio.h`.
| Function | Description | Old AVR Examples | Old ChibiOS/ARM Examples |
|`setPinInput(pin)` | Set pin as input with high impedance (High-Z) | `DDRB &= ~(1<<2)` | `palSetLineMode(pin, PAL_MODE_INPUT)` |
|`setPinInputHigh(pin)` | Set pin as input with builtin pull-up resistor |`DDRB&=~(1<<2);PORTB\|=(1<<2)` | `palSetLineMode(pin, PAL_MODE_INPUT_PULLUP)` |
|`setPinInputLow(pin)` | Set pin as input with builtin pull-down resistor | N/A (Not supported on AVR) | `palSetLineMode(pin, PAL_MODE_INPUT_PULLDOWN)`|
|`setPinOutput(pin)` | Set pin as output (alias of `setPinOutputPushPull`) | `DDRB \|= (1<<2)` | `palSetLineMode(pin, PAL_MODE_OUTPUT_PUSHPULL)` |
|`setPinOutputPushPull(pin)` | Set pin as output, push/pull mode |`DDRB \|= (1<<2)` | `palSetLineMode(pin, PAL_MODE_OUTPUT_PUSHPULL)` |
|`setPinOutputOpenDrain(pin)` | Set pin as output, open-drain mode | N/A (Not implemented on AVR) | `palSetLineMode(pin, PAL_MODE_OUTPUT_OPENDRAIN)` |
|`writePinHigh(pin)` | Set pin level as high, assuming it is an output | `PORTB \|= (1<<2)` | `palSetLine(pin)` |
|`writePinLow(pin)` | Set pin level as low, assuming it is an output | `PORTB &= ~(1<<2)` | `palClearLine(pin)` |
|`writePin(pin, level)` | Set pin level, assuming it is an output |`(level)?PORTB\|=(1<<2):PORTB&=~(1<<2)`|`(level)?palSetLine(pin) : palClearLine(pin)` |
|`readPin(pin)` | Returns the level of the pin | `_SFR_IO8(pin >> 4) & _BV(pin & 0xF)` | `palReadLine(pin)` |
|`togglePin(pin)` | Invert pin level, assuming it is an output | `PORTB ^= (1<<2)` | `palToggleLine(pin)` |
## Macros :id=macros
The following macros provide basic control of GPIOs and are found in `platforms/<platform>/gpio.h`.
|`gpio_set_pin_input(pin)` |Set pin as input with high impedance (High-Z) |
|`gpio_set_pin_input_high(pin)` |Set pin as input with builtin pull-up resistor |
|`gpio_set_pin_input_low(pin)` |Set pin as input with builtin pull-down resistor (unavailable on AVR)|
|`gpio_set_pin_output(pin)` |Set pin as output (alias of `gpio_set_pin_output_push_pull`) |
|`gpio_set_pin_output_push_pull(pin)` |Set pin as output, push/pull mode |
|`gpio_set_pin_output_open_drain(pin)`|Set pin as output, open-drain mode (unavailable on AVR and ATSAM) |
|`gpio_write_pin_high(pin)` |Set pin level as high, assuming it is an output |
|`gpio_write_pin_low(pin)` |Set pin level as low, assuming it is an output |
|`gpio_write_pin(pin, level)` |Set pin level, assuming it is an output |
|`gpio_read_pin(pin)` |Returns the level of the pin |
|`gpio_toggle_pin(pin)` |Invert pin level, assuming it is an output |
## Advanced Settings :id=advanced-settings
Each microcontroller can have multiple advanced settings regarding its GPIO. This abstraction layer does not limit the use of architecture-specific functions. Advanced users should consult the datasheet of their desired device and include any needed libraries. For AVR, the standard avr/io.h library is used; for STM32, the ChibiOS [PAL library](https://chibios.sourceforge.net/docs3/hal/group___p_a_l.html) is used.
Each microcontroller can have multiple advanced settings regarding its GPIO. This abstraction layer does not limit the use of architecture-specific functions. Advanced users should consult the datasheet of their desired device. For AVR, the standard `avr/io.h` library is used; for STM32, the ChibiOS [PAL library](https://chibios.sourceforge.net/docs3/hal/group___p_a_l.html) is used.
## Atomic Operation
## Atomic Operation :id=atomic-operation
The above functions are not always guaranteed to work atomically. Therefore, if you want to prevent interruptions in the middle of operations when using multiple combinations of the above functions, use the following `ATOMIC_BLOCK_FORCEON` macro.
Ryan
2 months ago
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