The main header file of the GPIO library. More...

#include "bcm2835_gpio.h"
#include <stdio.h>
#include <stdint.h>

Macros
#define	CORE_CLK_HZ 250000000
	Speed of the core clock core_clk.

#define	ERRORS
	The list of errors which may be returned from gpio functions. More...

#define	ERROR(x) x,
	Redefining to replace the macro with x.

#define	I2C_CLOCK_FREQ_MIN 10000
	Minimum I2C frequency (Hertz)

#define	I2C_CLOCK_FREQ_MAX 400000
	Maximum I2C frequency (Hertz)

#define	DBG_INFO stderr,__FILE__,__LINE__
	Macro which covers the first three arguments of dbgPrint.

#define	REV1_PINCNT 17
	Pin count on a PCB rev1 Raspberry Pi.

#define	REV2_PINCNT 17
	Pin count on a PCB rev2 Raspberry Pi.

#define	REV1_PINS {0, 1, 4, 7, 8, 9, 10, 11, 14, 15, 17, 18, 21, 22, 23, 24, 25}

#define	REV2_PINS {2, 3, 4, 7, 8, 9, 10, 11, 14, 15, 17, 18, 22, 23, 24, 25, 27}

#define	REV1_SDA 0
	The BCM2835 pin number of SDA on rev1 Raspberry Pi.

#define	REV1_SCL 1
	The BCM2835 pin number of SCL on rev1 Raspberry Pi.

#define	REV2_SDA 2
	The BCM2835 pin number of SDA on rev2 Raspberry Pi.

#define	REV2_SCL 3
	The BCM2835 pin number of SCL on rev2 Raspberry Pi.

Enumerations
enum	errStatus { ERROR_MAX }
	The enum of possible errors returned from gpio functions. Errors themselves are defined in the macro ERRORS.

enum	eState { low = 0x0, high = 0x1 }
	The enum of possible pin states in input/output modes. More...

enum	eResistor { pullDisable = GPPUD_DISABLE, pulldown = GPPUD_PULLDOWN, pullup = GPPUD_PULLUP }
	The enum for possible pull resistors. More...

enum	eFunction { input = GPFSEL_INPUT, output = GPFSEL_OUTPUT, alt0 = GPFSEL_ALT0, alt1 = GPFSEL_ALT1, alt2 = GPFSEL_ALT2, alt3 = GPFSEL_ALT3, alt4 = GPFSEL_ALT4, alt5 = GPFSEL_ALT5, eFunctionMin = GPFSEL_INPUT, eFunctionMax = GPFSEL_ALT3 }
	The enum of pin functions available. More...

enum	tPcbRev { pcbRevError = 0, pcbRev1 = 1, pcbRev2 = 2 }
	valid PCB revision values

Functions
errStatus	gpioSetup (void)
	Maps the memory used for GPIO access. This function must be called prior to any of the other GPIO calls. More...

errStatus	gpioCleanup (void)
	Unmaps the memory used for the gpio pins. This function should be called when finished with the GPIO pins. More...

errStatus	gpioSetFunction (int gpioNumber, eFunction function)
	Sets the functionality of the desired pin. More...

errStatus	gpioSetPin (int gpioNumber, eState state)
	Sets a pin to high or low. More...

errStatus	gpioReadPin (int gpioNumber, eState *state)
	Reads the current state of a gpio pin. More...

errStatus	gpioSetPullResistor (int gpioNumber, eResistor resistor)
	Allows configuration of the internal resistor at a GPIO pin. More...

errStatus	gpioGetI2cPins (int gpioNumberScl, int gpioNumberSda)
	Get the correct I2C pins. More...

errStatus	gpioI2cSetup (void)
	Initial setup of I2C functionality. More...

errStatus	gpioI2cCleanup (void)
	Disables the I2C controller and unmaps the memory used for the i2c functionality. This function should be called when finished with the I2C module. More...

errStatus	gpioI2cSetClock (int frequency)
	Sets the I2C Clock Frequency. More...

errStatus	gpioI2cSet7BitSlave (uint8_t slaveAddress)
	Sets the 7-bit slave address to communicate with. More...

errStatus	gpioI2cWriteData (const uint8_t *data, uint16_t dataLength)
	Writes `data` to the address previously specified by gpioI2cSet7BitSlave(). More...

errStatus	gpioI2cReadData (uint8_t *buffer, uint16_t bytesToRead)
	Read a number of bytes from I2C. The slave address should have been previously set with gpioI2cSet7BitSlave(). More...

const char *	gpioErrToString (errStatus error)
	Debug function which converts an error from errStatus to a string. More...

int	dbgPrint (FILE stream, const char file, int line, const char *format,...)
	Debug function wrapper for fprintf(). More...

Detailed Description

The main header file of the GPIO library.

This is is part of https://github.com/alanbarr/RaspberryPi-GPIO a C library for basic control of the Raspberry Pi's GPIO pins. Copyright (C) Alan Barr 2012

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Definition in file rpiGpio.h.

Macro Definition Documentation

◆ ERRORS

#define ERRORS

Value:

ERROR(OK)                           \
    ERROR(ERROR_DEFAULT)                \
    ERROR(ERROR_INVALID_PIN_NUMBER)     \
    ERROR(ERROR_RANGE)                  \
    ERROR(ERROR_NULL)                   \
    ERROR(ERROR_EXTERNAL)               \
    ERROR(ERROR_NOT_INITIALISED)        \
    ERROR(ERROR_ALREADY_INITIALISED)    \
    ERROR(ERROR_I2C_NACK)               \
    ERROR(ERROR_I2C)                    \
    ERROR(ERROR_I2C_CLK_TIMEOUT)        \
    ERROR(ERROR_INVALID_BSC)        \

The list of errors which may be returned from gpio functions.

Errors are defined within ERROR(x).

Definition at line 35 of file rpiGpio.h.

◆ REV1_PINS

#define REV1_PINS {0, 1, 4, 7, 8, 9, 10, 11, 14, 15, 17, 18, 21, 22, 23, 24, 25}

@ brief List of all BCM2835 pins available through the rev1 Raspberry Pi header

Definition at line 129 of file rpiGpio.h.

◆ REV2_PINS

#define REV2_PINS {2, 3, 4, 7, 8, 9, 10, 11, 14, 15, 17, 18, 22, 23, 24, 25, 27}

@ brief List of all BCM2835 pins available through the rev2 Raspberry Pi header

Definition at line 131 of file rpiGpio.h.

Enumeration Type Documentation

◆ eFunction

enum eFunction

The enum of pin functions available.

The enum values are equivalent to those in the data sheet.

Note: Currently only pins configured for input and output have been tested.

Enumerator
input	Set pin to input
output	Set pin to output
alt0	Set pin to alternative function 0
alt1	Set pin to alternative function 1
alt2	Set pin to alternative function 2
alt3	Set pin to alternative function 3
alt4	Set pin to alternative function 4
alt5	Set pin to alternative function 5
eFunctionMin	Minimum valid value for enum
eFunctionMax	Maximum valid value for enum

Definition at line 85 of file rpiGpio.h.

◆ eResistor

enum eResistor

The enum for possible pull resistors.

Enumerator
pullDisable	No resistor
pulldown	Pulldown resistor
pullup	Pullup resistor

Definition at line 75 of file rpiGpio.h.

◆ eState

enum eState

The enum of possible pin states in input/output modes.

Enumerator
low	Pin low
high	Pin high

Definition at line 69 of file rpiGpio.h.

Function Documentation

◆ dbgPrint()

int dbgPrint	(	FILE *	stream,
		const char *	file,
		int	line,
		const char *	format,
			...
	)

Debug function wrapper for fprintf().

Allows file and line information to be added easier to output strings. DBG_INFO is a macro which is useful to call as the "first" parameter to this function. Note this function will add on a newline to the end of a format string so one is generally not required in format.

Parameters

[in]	stream	Output stream for strings, e.g. stderr, stdout.
[in]	file	Name of file to be printed. Should be retrieved with FILE.
	line	Line number to print. Should be retrieved with LINE.
[in]	format	Formatted string in the format which printf() would accept.
	...	Additional arguments - to fill in placeholders in parameter `format`.

Returns: This function uses the printf() family functions and the returned integer is what is returned from these calls: If successful the number or characters printed is returned, if unsuccessful a negative value.

Definition at line 439 of file gpio.c.

◆ gpioCleanup()

errStatus gpioCleanup ( void )

Unmaps the memory used for the gpio pins. This function should be called when finished with the GPIO pins.

Returns: An error from errStatus.

Definition at line 134 of file gpio.c.

◆ gpioErrToString()

const char* gpioErrToString ( errStatus error )

Debug function which converts an error from errStatus to a string.

Parameters

error Error from errStatus.

Returns: String representation of errStatus parameter error.

Definition at line 405 of file gpio.c.

◆ gpioGetI2cPins()

errStatus gpioGetI2cPins	(	int *	gpioNumberScl,
		int *	gpioNumberSda
	)

Get the correct I2C pins.

The different revisions of the PI have their I2C ports on different GPIO pins which require different BSC modules.

Parameters

[out]	gpioNumberScl	Integer to be populated with scl gpio number.
[out]	gpioNumberSda	Integer to be populated with sda gpio number.

Todo:: TODO Does this need to be public or internal only?

Returns: An error from errStatus.

Definition at line 356 of file gpio.c.

◆ gpioI2cCleanup()

errStatus gpioI2cCleanup ( void )

Disables the I2C controller and unmaps the memory used for the i2c functionality. This function should be called when finished with the I2C module.

Returns: An error from errStatus.

Definition at line 156 of file i2c.c.

◆ gpioI2cReadData()

errStatus gpioI2cReadData	(	uint8_t *	buffer,
		uint16_t	bytesToRead
	)

Read a number of bytes from I2C. The slave address should have been previously set with gpioI2cSet7BitSlave().

Parameters

[out]	buffer	A pointer to a user defined buffer which will store the bytes.
	bytesToRead	The number of bytes to read.

Returns: An error from errStatus.

Definition at line 348 of file i2c.c.

◆ gpioI2cSet7BitSlave()

errStatus gpioI2cSet7BitSlave ( uint8_t slaveAddress )

Sets the 7-bit slave address to communicate with.

This value can be set once and left if communicating with the same device.

Parameters

slaveAddress 7-bit slave address.

Returns: An error from errStatus.

Definition at line 217 of file i2c.c.

◆ gpioI2cSetClock()

errStatus gpioI2cSetClock ( int frequency )

Sets the I2C Clock Frequency.

Note: The desired frequency should be in the range: I2C_CLOCK_FREQ_MIN <= frequency <= I2C_CLOCK_FREQ_MAX.

Parameters

frequency Desired frequency in Hertz.

Returns: An error from errStatus

Definition at line 465 of file i2c.c.

◆ gpioI2cSetup()

errStatus gpioI2cSetup ( void )

Initial setup of I2C functionality.

gpioSetup() should be called prior to this.

Returns: An error from errStatus.

Definition at line 36 of file i2c.c.

◆ gpioI2cWriteData()

errStatus gpioI2cWriteData	(	const uint8_t *	data,
		uint16_t	dataLength
	)

Writes data to the address previously specified by gpioI2cSet7BitSlave().

Parameters

[in]	data	Pointer to the start of data to transmit.
	dataLength	The length of `data`.

Returns: errStatus An error from errStatus

Definition at line 243 of file i2c.c.

◆ gpioReadPin()

errStatus gpioReadPin	(	int	gpioNumber,
		eState *	state
	)

Reads the current state of a gpio pin.

Parameters

	gpioNumber	The number of the GPIO pin to read.
[out]	state	Pointer to the variable in which the GPIO pin state is returned.

Returns: An error from errStatus.

Definition at line 255 of file gpio.c.

◆ gpioSetFunction()

errStatus gpioSetFunction	(	int	gpioNumber,
		eFunction	function
	)

Sets the functionality of the desired pin.

Parameters

gpioNumber	The gpio pin number to change.
function	The desired functionality for the pin.

Returns: An error from errStatus.

Definition at line 164 of file gpio.c.

◆ gpioSetPin()

errStatus gpioSetPin	(	int	gpioNumber,
		eState	state
	)

Sets a pin to high or low.

The pin should be configured as an ouput with gpioSetFunction() prior to this.

Parameters

gpioNumber	The pin to set.
state	The desired state of the pin.

Returns: An error from errStatus.

Definition at line 208 of file gpio.c.

◆ gpioSetPullResistor()

errStatus gpioSetPullResistor	(	int	gpioNumber,
		eResistor	resistorOption
	)

Allows configuration of the internal resistor at a GPIO pin.

The GPIO pins on the BCM2835 have the option of configuring a pullup, pulldown or no resistor at the pin.

Parameters

gpioNumber	The GPIO pin to configure.
resistorOption	The available resistor options.

Returns: An error from errStatus.

Definition at line 302 of file gpio.c.

◆ gpioSetup()

errStatus gpioSetup ( void )

Maps the memory used for GPIO access. This function must be called prior to any of the other GPIO calls.

Returns: An error from errStatus.

Definition at line 44 of file gpio.c.

Macros

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ ERRORS

◆ REV1_PINS

◆ REV2_PINS

Enumeration Type Documentation

◆ eFunction

◆ eResistor

◆ eState

Function Documentation

◆ dbgPrint()

◆ gpioCleanup()

◆ gpioErrToString()

◆ gpioGetI2cPins()

◆ gpioI2cCleanup()

◆ gpioI2cReadData()

◆ gpioI2cSet7BitSlave()

◆ gpioI2cSetClock()

◆ gpioI2cSetup()

◆ gpioI2cWriteData()

◆ gpioReadPin()

◆ gpioSetFunction()

◆ gpioSetPin()

◆ gpioSetPullResistor()

◆ gpioSetup()