GPIO — `pymcu.hal.gpio`#

from pymcu.hal.gpio import Pin

Digital input/output control. Pin is an @inline class — it compiles to DDR/PORT register writes with zero SRAM allocation.

class `Pin`#

`Pin(name, mode, pull=-1, value=-1)`#

Creates a GPIO pin. All parameters except name and mode are optional.

Parameter	Type	Description
`name`	`str`	Port/pin name: `"PB5"`, `"PD2"`, `"PC0"`, etc.
`mode`	`uint8`	`Pin.OUT` or `Pin.IN`
`pull`	`uint8`	`Pin.PULL_UP` or `Pin.PULL_DOWN` (input only)
`value`	`uint8`	Initial output value (output only)

Constants#

Constant	Value	Description
`Pin.OUT`	0	Output mode
`Pin.IN`	1	Input mode
`Pin.OPEN_DRAIN`	2	Open-drain output
`Pin.PULL_UP`	1	Enable pull-up resistor
`Pin.PULL_DOWN`	2	Enable pull-down resistor
`Pin.IRQ_FALLING`	1	Interrupt on falling edge
`Pin.IRQ_RISING`	2	Interrupt on rising edge
`Pin.IRQ_LOW_LEVEL`	4	Interrupt on low level
`Pin.IRQ_HIGH_LEVEL`	8	Interrupt on high level

Methods#

Method	Description
`high()`	Drive pin high
`low()`	Drive pin low
`on()`	Alias for `high()`
`off()`	Alias for `low()`
`toggle()`	XOR pin with 1
`value(x=-1)`	Read pin if `x == -1`, else write `x`
`mode(m=-1)`	Read current mode if `m == -1`, else set mode
`pull(p)`	Configure pull resistor
`irq(trigger)`	Configure interrupt trigger hardware
`pulse_in(state, timeout_us=1000)`	Measure pulse width in microseconds

Examples#

Output pin#

from pymcu.hal.gpio import Pin

led = Pin("PB5", Pin.OUT)
led.high()
led.low()
led.toggle()

Input pin with pull-up#

from pymcu.hal.gpio import Pin
from pymcu.types import uint8

btn = Pin("PD2", Pin.IN, pull=Pin.PULL_UP)
v: uint8 = btn.value()

Interrupt-driven input#

from pymcu.hal.gpio import Pin
from pymcu.types import uint8

count: uint8 = 0

@interrupt(0x0002)      # INT0 vector (ATmega328P, pin D2)
def on_press():
    global count
    count += 1

def main():
    btn = Pin("PD2", Pin.IN, pull=Pin.PULL_UP)
    btn.irq(Pin.IRQ_FALLING)    # configure EICRA/EIMSK hardware
    # sei is emitted automatically when @interrupt handler exists
    while True:
        pass

Pulse measurement (e.g. HC-SR04)#

from pymcu.hal.gpio import Pin
from pymcu.types import uint16

echo = Pin("PD4", Pin.IN)
width: uint16 = echo.pulse_in(1, timeout_us=30000)
# width is duration in microseconds; 0 on timeout

Board pin names#

from pymcu.boards.arduino_uno import D13, D2, A0, LED_BUILTIN

led = Pin(LED_BUILTIN, Pin.OUT)    # same as Pin("PB5", Pin.OUT)
btn = Pin(D2, Pin.IN)              # same as Pin("PD2", Pin.IN)

Arduino Uno pin mapping#

Integer	Arduino silk	Port	Notes
0	D0 / RX	PD0	USART0 RX
1	D1 / TX	PD1	USART0 TX
2	D2	PD2	INT0
3	D3	PD3	INT1 / OC2B
5	D5	PD5	OC0B (Timer0 PWM)
6	D6	PD6	OC0A (Timer0 PWM)
9	D9	PB1	OC1A (Timer1 PWM)
10	D10	PB2	OC1B (Timer1 PWM)
11	D11	PB3	OC2A / MOSI
13	D13 / LED	PB5	Built-in LED / SCK
A0–A3	A0–A3	PC0–PC3	ADC0–ADC3
A4 / SDA	A4	PC4	I2C SDA
A5 / SCL	A5	PC5	I2C SCL