164 lines
4.8 KiB
Markdown
164 lines
4.8 KiB
Markdown
# GPIO Module
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| Since | Origin / Contributor | Maintainer | Source |
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| :----- | :-------------------- | :---------- | :------ |
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| 2014-12-22 | [Zeroday](https://github.com/funshine) | [Zeroday](https://github.com/funshine) | [gpio.c](../../../app/modules/gpio.c)|
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This module provides access to the [GPIO](https://en.wikipedia.org/wiki/General-purpose_input/output) (General Purpose Input/Output) subsystem.
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All access is based on the I/O index number on the NodeMCU dev kits, not the internal GPIO pin. For example, the D0 pin on the dev kit is mapped to the internal GPIO pin 16.
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If not using a NodeMCU dev kit, please refer to the below GPIO pin maps for the index↔gpio mapping.
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| IO index | ESP8266 pin | IO index | ESP8266 pin |
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|---------:|:------------|---------:|:------------|
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| 0 [*] | GPIO16 | 7 | GPIO13 |
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| 1 | GPIO5 | 8 | GPIO15 |
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| 2 | GPIO4 | 9 | GPIO3 |
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| 3 | GPIO0 | 10 | GPIO1 |
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| 4 | GPIO2 | 11 | GPIO9 |
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| 5 | GPIO14 | 12 | GPIO10 |
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| 6 | GPIO12 | | |
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** [*] D0(GPIO16) can only be used as gpio read/write. No support for open-drain/interrupt/pwm/i2c/ow. **
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## gpio.mode()
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Initialize pin to GPIO mode, set the pin in/out direction, and optional internal weak pull-up.
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#### Syntax
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`gpio.mode(pin, mode [, pullup])`
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#### Parameters
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- `pin` pin to configure, IO index
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- `mode` one of gpio.OUTPUT, gpio.OPENDRAIN, gpio.INPUT, or gpio.INT (interrupt mode)
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- `pullup` gpio.PULLUP enables the weak pull-up resistor; default is gpio.FLOAT
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#### Returns
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`nil`
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#### Example
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```lua
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gpio.mode(0, gpio.OUTPUT)
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```
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#### See also
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- [`gpio.read()`](#gpioread)
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- [`gpio.write()`](#gpiowrite)
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## gpio.read()
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Read digital GPIO pin value.
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#### Syntax
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`gpio.read(pin)`
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#### Parameters
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`pin` pin to read, IO index
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#### Returns
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a number, 0 = low, 1 = high
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#### Example
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```lua
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-- read value of gpio 0.
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gpio.read(0)
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```
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#### See also
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[`gpio.mode()`](#gpiomode)
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## gpio.serout()
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Serialize output based on a sequence of delay-times. After each delay, the pin is toggled.
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#### Syntax
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`gpio.serout(pin, start_level, delay_times [, repeat_num])`
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#### Parameters
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- `pin` pin to use, IO index
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- `start_level` level to start on, either `gpio.HIGH` or `gpio.LOW`
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- `delay_times` an array of delay times between each toggle of the gpio pin.
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- `repeat_num` an optional number of times to run through the sequence.
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Note that this function blocks, and as such any use of it must adhere to the SDK guidelines of time spent blocking the stack (10-100ms). Failure to do so may lead to WiFi issues or outright crashes/reboots.
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#### Returns
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`nil`
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#### Example
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```lua
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gpio.mode(1,gpio.OUTPUT,gpio.PULLUP)
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gpio.serout(1,1,{30,30,60,60,30,30}) -- serial one byte, b10110010
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gpio.serout(1,1,{30,70},8) -- serial 30% pwm 10k, lasts 8 cycles
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gpio.serout(1,1,{3,7},8) -- serial 30% pwm 100k, lasts 8 cycles
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gpio.serout(1,1,{0,0},8) -- serial 50% pwm as fast as possible, lasts 8 cycles
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gpio.serout(1,0,{20,10,10,20,10,10,10,100}) -- sim uart one byte 0x5A at about 100kbps
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gpio.serout(1,1,{8,18},8) -- serial 30% pwm 38k, lasts 8 cycles
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```
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## gpio.trig()
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Establish or clear a callback function to run on interrupt for a pin.
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This function is not available if GPIO_INTERRUPT_ENABLE was undefined at compile time.
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#### Syntax
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`gpio.trig(pin, [type [, callback_function]])`
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#### Parameters
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- `pin` **1-12**, pin to trigger on, IO index. Note that pin 0 does not support interrupts.
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- `type` "up", "down", "both", "low", "high", which represent *rising edge*, *falling edge*, *both
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edges*, *low level*, and *high level* trigger modes respectivey. If the type is "none" or omitted
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then the callback function is removed and the interrupt is disabled.
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- `callback_function(level)` callback function when trigger occurs. The level of the specified pin
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at the interrupt passed as the parameter to the callback. The previous callback function will be
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used if the function is omitted.
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#### Returns
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`nil`
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#### Example
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```lua
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do
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-- use pin 1 as the input pulse width counter
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local pin, pulse1, du, now, trig = 1, 0, 0, tmr.now, gpio.trig
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gpio.mode(pin,gpio.INT)
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local function pin1cb(level)
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local pulse2 = now()
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print( level, pulse2 - pulse1 )
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pulse1 = pulse2
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trig(pin, level == gpio.HIGH and "down" or "up")
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end
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trig(pin, "down", pin1cb)
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end
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```
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#### See also
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[`gpio.mode()`](#gpiomode)
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## gpio.write()
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Set digital GPIO pin value.
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#### Syntax
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`gpio.write(pin, level)`
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#### Parameters
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- `pin` pin to write, IO index
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- `level` `gpio.HIGH` or `gpio.LOW`
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#### Returns
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`nil`
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#### Example
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```lua
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-- set pin index 1 to GPIO mode, and set the pin to high.
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pin=1
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gpio.mode(pin, gpio.OUTPUT)
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gpio.write(pin, gpio.HIGH)
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```
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#### See also
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- [`gpio.mode()`](#gpiomode)
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- [`gpio.read()`](#gpioread)
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