mpr121.h File Reference

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API Description

//Modified: Abhishek Malik <abhishek.malik@intel.com>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include "mpr121.h"

#include "upm_utilities.h"

int main()
{
    mpr121_context dev = mpr121_init(MPR121_I2C_BUS, MPR121_DEFAULT_I2C_ADDR);

    if(mpr121_config_an3944(dev) != UPM_SUCCESS){
        printf("unable to configure device\n");
    }
    uint32_t states;
    while(1){
        if(mpr121_read_buttons(dev, &states, 0) != UPM_SUCCESS){
            printf("Error while reading button values\n");
        }
        printf("retrieved button states: %d\n", states);
        upm_delay(1);
    }

    mpr121_close(dev);
    printf("all done!!\n");

    return 0;
}

Go to the source code of this file.

Data Structures
struct	_mpr121_context

Functions
mpr121_context	mpr121_init (int bus, uint8_t address)
void	mpr121_close (mpr121_context dev)
upm_result_t	mpr121_config_an3944 (mpr121_context dev)
upm_result_t	mpr121_read_buttons (mpr121_context dev, uint32_t *states, int num)
upm_result_t	mpr121_write_bytes (mpr121_context dev, uint8_t reg, uint8_t *buffer, int len)
upm_result_t	mpr121_read_bytes (mpr121_context dev, uint8_t reg, uint8_t *buffer, int len)

Macros
#define	MPR121_I2C_BUS   0
#define	MPR121_DEFAULT_I2C_ADDR   0x5a

Typedefs
typedef struct _mpr121_context *	mpr121_context

Function Documentation

mpr121_context mpr121_init	(	int	bus,
		uint8_t	address
	)

MPR121 Init function

Parameters

bus	i2c bus
address	i2c address of the sensor

Returns

void* pointer to the sensor struct

void mpr121_close

(

mpr121_context

dev

)

MPR121 Close function

Parameters

dev	pointer to sensor struct

upm_result_t mpr121_config_an3944

(

mpr121_context

dev

)

Sets up a default configuration, based on Application Note 3944 (AN3944): http://cache.freescale.com/files/sensors/doc/app_note/AN3944.pdf

After configuration, the sensor is left in the run state.

Parameters

dev	pointer to the sensor struct

Returns

upm_result_t UPM success/error code

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upm_result_t mpr121_read_buttons	(	mpr121_context	dev,
		uint32_t *	states,
		int	num
	)

Function to read the individual button values

Parameters

dev	pointer to the sensor struct
states	Pointer to store the states of the individual buttons
num	used to retrieve the state of a particular button

Returns

upm_result_t UPM success/error code

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upm_result_t mpr121_write_bytes	(	mpr121_context	dev,
		uint8_t	reg,
		uint8_t *	buffer,
		int	len
	)

Function used to write multiple bytes to the i2c bus

Parameters

dev	sensor struct
reg	i2c register to read from
*buffer	pointer that contains the values that have to be written to the registers
len	length of the values that have to be written to the regs

Returns

upm_result_t UPM success/error code

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upm_result_t mpr121_read_bytes	(	mpr121_context	dev,
		uint8_t	reg,
		uint8_t *	buffer,
		int	len
	)

Function used to read multiple bytes from the i2c bus

Parameters

dev	sensor struct
reg	i2c register to read from
*buffer	pointer that contains the values that have been read from the registers
len	length of the values that have to be read

Returns

upm_result_t UPM success/error code

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Typedef Documentation

typedef struct _mpr121_context * mpr121_context

device context