spi.c File Reference

SPI general purpose interface code for file system. More...

#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include "include/linux/spi/spidev.h"
#include "bbbandroidHAL.h"

Macros
#define	MAX_PATH   50
#define	MODE0   0
#define	MODE1   1
#define	MODE2   2
#define	MODE3   3

Functions
int	spiTransfer (const int spiFD, const uint8_t tx[], const uint8_t rx[], const int len)
int	spiReadByte (const int spiFD, const uint8_t regAdd)
unsigned char *	spiReadBytes (const int spiFD, const int len, const uint8_t startAdd)
int	spiWriteRegByte (const int spiFD, const uint8_t regAdd, const uint8_t data)
int	spiWriteBytes (const int spiFD, const uint8_t data[], const int len)
int	spiSetMode (const int spiFD, const uint8_t mode)
int	spiSetSpeed (const int spiFD, const uint32_t speed)
int	spiSetBitsPerWord (const int spiFD, const uint8_t bpw)
int	spiOpen (const uint8_t bus, const uint8_t device, const uint32_t speed, const uint8_t mode, const uint8_t bpw)
void	spiClose (const int spiFD)

Detailed Description

SPI general purpose interface code for file system.

Author

Ankur Yadav (ankur.nosp@m.ayad.nosp@m.av@gm.nosp@m.ail..nosp@m.com)

Macro Definition Documentation

#define MAX_PATH   50

Maximum buffer for creating path using snprintf()

#define MODE0   0

Macro defination for MODE0

#define MODE1   1

Macro defination for MODE1

#define MODE2   2

Macro defination for MODE2

#define MODE3   3

Macro defination for MODE3

Function Documentation

void spiClose

(

const int

spiFD

)

This function is used to close SPI file descriptor.

Parameters

spiFD

a constant integer argument.

int spiOpen	(	const uint8_t	bus,
		const uint8_t	device,
		const uint32_t	speed,
		const uint8_t	mode,
		const uint8_t	bpw
	)

This function takes input bus number, device number, speed of device, mode of device and bits per word for the device and internally opens the file and sets speed mode and bits per word for the device using spiSetMode(), spiSetSpeed() and spiSetBitsPerWord() and then returns the file descriptor.

Parameters

bus	a constant unsigned integer argument.
device	a constant uint8_t argument.
speed	a constant uint32_t argument.
mode	a constant uuint8_t argument.
bpw	a constant uuint8_t argument.

Returns

If successful then SPI file descriptor is returned and if it fails then -1 is returned.

int spiReadByte	(	const int	spiFD,
		const uint8_t	regAdd
	)

It takes spi file descriptor and register address as input and returns the value present at that address.

Parameters

spiFD	a constant integer argument.
regAdd	a constant uint8_t argument.

Returns

value present at that address.

unsigned char* spiReadBytes	(	const int	spiFD,
		const int	len,
		const uint8_t	startAdd
	)

It takes file descriptor, length of data to be read and starting address of register from which data is to be read and returns a pointer to the array of data bytes read. It is used to get 'length' number of bytes in array from 'startAdd' starting address.

Parameters

spiFD	a constant integer argument.
len	a constant integer argument.
startAdd	a constant uint8_t argument.

Returns

a pointer to the array of data bytes read.

int spiSetBitsPerWord	(	const int	spiFD,
		const uint8_t	bpw
	)

It takes file descriptor and 'bpw' bits per word as input and sets the bpw provided in the argument to the device represented by file descriptor.

Parameters

spiFD	a constant integer argument.
bpw	a constant uint8_t argument.

Returns

0 if successful and -1 if it fails.

int spiSetMode	(	const int	spiFD,
		const uint8_t	mode
	)

It takes file descriptor and mode as input and sets the mode provided in the argument to the device represented by file descriptor.

Parameters

spiFD	a constant integer argument.
mode	a constant uint8_t argument.

Returns

0 if successful and -1 if it fails.

int spiSetSpeed	(	const int	spiFD,
		const uint32_t	speed
	)

It takes file descriptor and speed as input and sets the speed provided in the argument to the device represented by file descriptor.

Parameters

spiFD	a constant integer argument.
speed	a constant uint32_t argument.

Returns

0 if successful and -1 if it fails.

int spiTransfer	(	const int	spiFD,
		const uint8_t	tx[],
		const uint8_t	rx[],
		const int	len
	)

This function takes input SPI file descriptor, tx buffer array to transmit data, rx buffer array to receive data and length of data to be transferred. It then transfers and receives data using ioctl function call.

Parameters

spiFD	a constant integer argument.
tx	a constant uint8_t array argument.
rx	a constant uint8_t array argument.
len	a constant integer argument.

Returns

0 if successful and -1 if it fails.

int spiWriteBytes	(	const int	spiFD,
		const uint8_t	data[],
		const int	len
	)

It takes spi file descriptor , array of data to be written and length of data to be written as input. It writes length number of data bytes from the data buffer provided.

Parameters

spiFD	a constant integer argument.
data	a constant uint8_t argument argument.
len	a constant integer argument.

Returns

0

int spiWriteRegByte	(	const int	spiFD,
		const uint8_t	regAdd,
		const uint8_t	data
	)

This function takes file descriptor, address of register to write and byte to be written as input and writes byte provided in the argument at the address provided.

Parameters

spiFD	a constant integer argument.
regAdd	a constant uint8_t argument.
data	a constant uint8_t argument.

Returns

0