hardware_gpio Library Functions

All the GPIOs in the μC are set to Input Pull-Down configuration during power up by default. To use this library, add following to the C/C++ file,

#include <hardware/gpio.h>

and following to the CMakeLists.txt file.

target_link_libraries(projectName pico_stdlib hardware_gpio)

Following are some of the most commonly used functions for configuring the GPIOs.

gpio_init(uint8_t pinNo)

This function initializes a GPIO to the peripheral function SIO (Single-Cycle IO). This function is similar to controlling a GPIO directly. However, this peripheral allows the processor to switch GPIO states in a single clock cycle.

• Function input pinNo can be any GPIO number, i.e. 0 through 29.

gpio_set_dir(uint8_t pinNo, bool dir)

This function configures a GPIO to Input or Output.

• Function input pinNo can be any GPIO number, i.e. 0 through 29.
• Function input dir must be a boolean value, i.e. 0 or false for Input and 1 or true for Output.

gpio_put(uint8_t pinNo, bool outVal)

This function drives a GPIO to High or Low if it is configured as an Output.

• Function input pinNo can be any GPIO number, i.e. 0 through 29.
• Function input outVal must be a boolean value, i.e. 0 to drive GPIO Low and 1 to drive GPIO High.

bool gpio_get(uint8_t pinNo)

This function reads the state of a GPIO.

• Function input pinNo can be any GPIO number, i.e. 0 through 29.
• Function returns 0 if the GPIO is in LOW state, else 1 if the GPIO is in HIGH state.

gpio_set_pulls(uint8_t pinNo, bool pUp, bool pDown)

This function enables or disables pull-down or pull-up resistors if the GPIO is configured as an Input.

• Function input pinNo can be any GPIO number, i.e. 0 through 29.
• Function input pUp must be a boolean value, i.e. 0 to disable and 1 to enable the pull-up resistor.
• Function input pDown must be a boolean value, i.e. 0 to disable and 1 to enable the pull-down resistor.

gpio_set_function(uint8_t pinNo, uint8_t func)

This function sets up the state of the GPIO to be controlled by a specific peripheral as discussed in the table.

• Function input pinNo can be any GPIO number, i.e. 0 through 29.
• Function input func must be an unsigned integer value from the table. Necessary constants representing different functions are already defined in the SDK as follows, GPIO_FUNC_SPI = 1, GPIO_FUNC_UART = 2, GPIO_FUNC_I2C = 3, GPIO_FUNC_PWM = 4,GPIO_FUNC_SIO = 5.

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