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opensteno_qmk/docs/internals_gpio_control.md
JohSchneider d26a14c169
add 'togglePin' convenience function (#8734) 
* add 'togglePin' conveniance function

for AVR and chibios

* drop outmost parantheses

Co-Authored-By: Konstantin Đorđević <vomindoraan@gmail.com>

* toggle pin on avrs

toggle a pin configured as output by writing the corresponding bit to the PIN register

Co-Authored-By: Takeshi ISHII <2170248+mtei@users.noreply.github.com>

* togglepin: add documentation for newly added function

* Update docs/internals_gpio_control.md

Co-Authored-By: Konstantin Đorđević <vomindoraan@gmail.com>

* on AVR: use PORTD to toggle the output

... since not all MCUs support toggling through writing to PIN

Co-Authored-By: Ryan <fauxpark@gmail.com>

Co-authored-by: Johannes <you@example.com>
Co-authored-by: Konstantin Đorđević <vomindoraan@gmail.com>
Co-authored-by: Takeshi ISHII <2170248+mtei@users.noreply.github.com>
Co-authored-by: Ryan <fauxpark@gmail.com>
2020-04-29 04:04:29 -07:00

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GPIO Control :id=gpio-control

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 can provide basic control of GPIOs and are found in quantum/quantum.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 DDRB |= (1<<2) palSetLineMode(pin, PAL_MODE_OUTPUT_PUSHPULL)
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)

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 is used.