Digital I/O

pinMode(), digitalWrite(), digitalRead(). More...

Functions
uint8_t	digitalPinToGpio (pin_size_t pin)
	RP2040 GPIO behind an Arduino pin, for use with the pico-sdk.
void	pinMode (pin_size_t pinNumber, PinMode pinMode)
	Sets a pin as an input or an output.
void	digitalWrite (pin_size_t pinNumber, PinStatus status)
	Sets an output pin HIGH (3.3 V) or LOW (0 V).
PinStatus	digitalRead (pin_size_t pinNumber)
	Reads the level on a pin.

Detailed Description

pinMode(), digitalWrite(), digitalRead().

All pins are 3.3 V. A3-A5 are analog only: digital functions ignore them.

Function Documentation

digitalPinToGpio()

uint8_t digitalPinToGpio ( pin_size_t pin )

inline

RP2040 GPIO behind an Arduino pin, for use with the pico-sdk.

Parameters

pin	Arduino pin number (e.g. 2, A0, LED_BUILTIN).

Returns

GPIO number, or NOT_A_GPIO for a pin with no GPIO behind it (A3-A5) or a pin number out of range.

digitalRead()

PinStatus digitalRead

(

pin_size_t

pinNumber

)

Reads the level on a pin.

Works in any mode, including OUTPUT (it reads back the pin). Inputs are HIGH above about 2 V and LOW below about 0.8 V.

Parameters

pinNumber

Arduino pin.

Returns

HIGH or LOW. Always LOW for A3-A5 and numbers out of range.

Note

After analogRead() on A0-A2, call pinMode() before digitalRead() on that pin: analogRead() turns off its digital input.

Examples

AnalogBurstBackground.ino, and FreeRtosTasks.ino.

digitalWrite()

void digitalWrite	(	pin_size_t	pinNumber,
		PinStatus	status )

Sets an output pin HIGH (3.3 V) or LOW (0 V).

What it does depends on the pin's mode:

• OUTPUT: drives the pin.
• OUTPUT_OPENDRAIN: LOW drives the pin low, HIGH releases it.
• INPUT: HIGH turns on the pull-up and LOW turns it off, as on an Uno.

Parameters

pinNumber	Arduino pin. A3-A5 and numbers out of range are ignored.
status	HIGH or LOW.

Note

Unlike an Uno, digitalWrite() does not stop analogWrite() or tone() output: call pinMode() first to use the pin as a plain output again.

Examples

AnalogBurstBackground.ino, CmsisRtos2Threads.ino, FreeRtosTasks.ino, MulticoreBasics.ino, and MulticoreFifo.ino.

pinMode()

void pinMode	(	pin_size_t	pinNumber,
		PinMode	pinMode )

Sets a pin as an input or an output.

Also stops analogWrite() or tone() output on the pin and returns it to a plain digital pin.

Parameters

pinNumber	Arduino pin (e.g. 2, A0, LED_BUILTIN). A3-A5 and numbers out of range are ignored.
pinMode	One of: INPUT: no pull resistor. INPUT_PULLUP, INPUT_PULLDOWN: the RP2040's weak internal pull-up or pull-down. OUTPUT: driven high or low. OUTPUT_OPENDRAIN: driven low, or released (floating) for HIGH. Needs a pull-up resistor.

Warning

The pins are 3.3 V and not 5 V tolerant: do not connect a 5 V signal directly.

Examples

AnalogBurstBackground.ino, CmsisRtos2Threads.ino, FreeRtosTasks.ino, MulticoreBasics.ino, and MulticoreFifo.ino.