GPIO library

Enumerations
enum	gpio_direction_t { GPIO_DIR_INPUT = 0 , GPIO_DIR_OUTPUT = 1 }
enum	gpio_level_t { GPIO_LEVEL_LOW = 0 , GPIO_LEVEL_HIGH = 1 }

Functions
void	gpio_init (void)
void	gpio_destroy (void)
void	gpio_reset_pin (const io_t pin)
void	gpio_set_direction (const io_t pin, const gpio_direction_t direction)
gpio_direction_t	gpio_get_direction (const io_t pin)
void	gpio_set_level (const io_t pin, const gpio_level_t level)
gpio_level_t	gpio_get_level (const io_t pin)
void	gpio_reset (void)
bool	gpio_is_initialized (void)

Detailed Description

Functions for General Purpose I/O (GPIO) access to leds, buttons, (analog) pins, etc.

All functions use the IO pin number (io_t) from 0..IO_NUM_PINS-1.

The LED and button libraries are built on top of this library, but do not expose the full functionality of this library. Use this library when that is required. Also see the I/O switchbox (switchbox.h) and pin mapping (pinmap.h).

In particular, be aware that the numbering used in the high-level libraries is different from the underlying GPIO numbering.

• The button library uses 0..3 or BUTTON0..BUTTON3, and 0..1 or SWITCH0..SWITCH1, whereas GPIO uses IO_BTN0..IO_BTN3 and IO_SW0..IO_SW1.
• The LED library uses 0..3 or LED0..LED1 for green LEDs whereas GPIO uses IO_LD0..IO_LD3. It uses 0..1 or COLOR_LED0..COLOR_LED1 and the three color components (RGB) whereas GPIO uses IO_LD4/5R/G/B.
• The PWM library uses 0..5 or PWM0..PWM5, whereas GPIO uses SWB_PWM0..SWB_PWM5.
• The UART library uses 0..1 or UART0..UART1, whereas GPIO uses SWB_UART0..SWB_UART1.
• The ADC library is slightly different. It uses ADC0..ADC5 (these are non-consecutive numbers), whereas GPIO uses IO_A0..IO_A5 (which are consecutive).

An example of using this library to turn LED0 on:

#include <libpynq.h>
int main (void)
{
  gpio_init();
  // set pin A0 to be an input pin and read from it
  gpio_set_direction(IO_A0, GPIO_DIR_INPUT);
  gpio_level_t c = gpio_get_level(IO_A0);
  // alternatively, set A0 to be an output pin and write to it
  gpio_set_direction(IO_A0, GPIO_DIR_OUTPUT);
  gpio_set_level(IO_A0, GPIO_LEVEL_LOW);
  sleep_msec(100);
  gpio_set_level(IO_A0, GPIO_LEVEL_HIGH);
 
  // set LED 0 as output
  gpio_set_direction(IO_LD0, GPIO_DIR_OUTPUT);
  // turn LED 0 on
  gpio_set_level(IO_LD0, GPIO_LEVEL_HIGH);
  sleep_msec(1000);
  leds_destroy(); // turn LEDs off
  pynq_destroy();
  return EXIT_SUCCESS;
}

Enumeration Type Documentation

gpio_direction_t

enum gpio_direction_t

Enumerate the direction state (input/output) of the pin

Enumerator
GPIO_DIR_INPUT	The IO pin is an input.
GPIO_DIR_OUTPUT	The IO pin is an output.

Definition at line 88 of file gpio.h.

gpio_level_t

enum gpio_level_t

Enumerate the signal level.

Enumerator
GPIO_LEVEL_LOW	A low signal
GPIO_LEVEL_HIGH	A high signal

Definition at line 98 of file gpio.h.

Function Documentation

gpio_destroy()

void gpio_destroy ( void  )

extern

De-initialize the GPIO library. This releases the memory map and memory allocated by gpio_init.

Definition at line 47 of file gpio.c.

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gpio_get_direction()

gpio_direction_t gpio_get_direction ( const io_t  pin )

extern

Returns the direction the set pin is initialized in.

Parameters

pin	The IO pin to read the direction set in the shared memory system on the ARM processor.

Warning

Fails with program exit when pin is outside valid range.

Definition at line 95 of file gpio.c.

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gpio_get_level()

gpio_level_t gpio_get_level ( const io_t  pin )

extern

Return the level of the IO pin.

Parameters

pin	The IO pin to read it state.

Returns

the output level of pin.

Warning

Fails with program exit when pin is outside valid range.

Definition at line 118 of file gpio.c.

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gpio_init()

void gpio_init ( void  )

extern

Initializes the GPIO library.

Definition at line 40 of file gpio.c.

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gpio_is_initialized()

bool gpio_is_initialized ( void  )

extern

Check if gpio library is initialized.

Returns

true if initialize, false if not.

Definition at line 35 of file gpio.c.

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gpio_reset()

void gpio_reset ( void  )

extern

Reset all IO pins.

Definition at line 62 of file gpio.c.

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gpio_reset_pin()

void gpio_reset_pin ( const io_t  pin )

extern

Function is currently a no-op placeholder for arduino compatibility.

Parameters

pin	The IO pin to reset.

Warning

Fails with program exit when LEDs were not initialized with the correct mode.

Definition at line 55 of file gpio.c.

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gpio_set_direction()

void gpio_set_direction ( const io_t  pin, const gpio_direction_t  direction  )

extern

Set the IO pin as in input or output.

Parameters

pin	The IO pin to modify direction for.
direction	The direction to set on the pin.

Warning

Fails with program exit when pin or direction is outside valid range.

Definition at line 81 of file gpio.c.

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gpio_set_level()

void gpio_set_level ( const io_t  pin, const gpio_level_t  level  )

extern

Set the level of the output IO pin. If the pin is configured as input, this function does nothing.

Parameters

pin	The IO pin to modify direction for.
level	The level to set on the pin.

Warning

Fails with program exit when pin is outside valid range.

Definition at line 104 of file gpio.c.

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