m2mb_i2c.h File Reference

I2C library implementation. More...

Go to the source code of this file.

Data Structures
struct	M2MB_I2C_MSG
	Structure to be used as container for a write or read operation in I2C Combined mode (M2MB_I2C_IOCTL_RDWR call) More...
struct	M2MB_I2C_RDWR_IOCTL_DATA
	Structure to be used with the M2MB_I2C_IOCTL_RDWR option in m2mb_i2c_ioctl call. More...
struct	M2MB_I2C_CFG_T
	I2C device configuration structure. More...

Macros
#define	NULL   0
#define	I2C_M_WR   0x0000
#define	I2C_M_RD   0x0001

Enumerations
enum	M2MB_I2C_IOCTL_REQUEST { M2MB_I2C_IOCTL_SET_CFG, M2MB_I2C_IOCTL_GET_CFG, M2MB_I2C_IOCTL_RDWR }
	enum used to access I2C configuration More...

Functions
INT32	m2mb_i2c_open (const CHAR *path, INT32 flags,...)
	open an I2C device More...
INT32	m2mb_i2c_close (INT32 fd)
	Close an I2C device. More...
INT32	m2mb_i2c_ioctl (INT32 fd, INT32 request,...)
	configure, read from and/or write to an I2C device More...
SSIZE_T	m2mb_i2c_read (INT32 fd, void *buf, SIZE_T nbyte)
	Read data from a connected I2C device. More...
SSIZE_T	m2mb_i2c_write (INT32 fd, const void *buf, SIZE_T nbyte)
	Write data to a connected I2C device. More...

Detailed Description

I2C library implementation.

m2m/m2m_generic/common/m2mb_inc/m2mb_i2c.h

The following functions are implemented: m2mb_i2c_ioctl m2mb_i2c_open m2mb_i2c_read m2mb_i2c_write m2mb_i2c_close

@notes Dependencies: m2mb_types.h

Author

Morgan Deidda

@changes Enrico Perini Cristina Angius

Date

31/08/2017 19/04/2021

Macro Definition Documentation

I2C_M_RD

#define I2C_M_RD   0x0001

read data, from slave to master

I2C_M_WR

#define I2C_M_WR   0x0000

write data, from master to slave

Enumeration Type Documentation

M2MB_I2C_IOCTL_REQUEST

enum M2MB_I2C_IOCTL_REQUEST

enum used to access I2C configuration

Enumerator
M2MB_I2C_IOCTL_SET_CFG	set i2c device configuration
M2MB_I2C_IOCTL_GET_CFG	get i2c device configuration
M2MB_I2C_IOCTL_RDWR	i2c combined format

Function Documentation

m2mb_i2c_close()

INT32 m2mb_i2c_close

(

INT32

fd

)

Close an I2C device.

This function closes an opened file descriptor.

Parameters

[in]

fd

File descriptor returned by m2mb_i2c_open

Returns

0 on SUCCESS, -1 on FAILURE

#define DEVICEADDR 0x0F  //e.g. the device address reported by device vendor on datasheet
CHAR path[32];
INT32 fd;
 
sprintf(path, "/dev/I2C-%d", DEVICEADDR << 1);
fd = m2mb_i2c_open( path, 0 );
if (-1 == fd)
{
     LOG("cannot open I2C channel");
     return -1;
}
 
m2mb_i2c_close(fd);

m2mb_i2c_ioctl()

INT32 m2mb_i2c_ioctl	(	INT32	fd,
		INT32	request,
			...
	)

configure, read from and/or write to an I2C device

Depending on request parameter, this function can configure an I2C device or can send and/or receive data through I2C combined format

Parameters

[in]	fd	file descriptor returned by m2mb_i2c_open
[in]	request	required operation (see M2MB_I2C_IOCTL_REQUEST)
[in]	cfg	pointer to the configuration structure M2MB_I2C_CFG_T casted to void* The parameter depends on request code: if request == M2MB_I2C_IOCTL_SET_CFG: in struct M2MB_I2C_CFG_T sdaPin, sclPin and registerId are mandatory SDA and SCL pins are mapped on GPIOs, the slave device register Id from which to read from (or to write to) is set if request == M2MB_I2C_IOCTL_GET_CFG: a pointer to the structure M2MB_I2C_CFG_T previously set is returned if request == M2MB_I2C_IOCTL_RDWR: in struct M2MB_I2C_CFG_T, sdaPin, sclPin, rw_param are mandatory SDA and SCL pins are mapped on GPIOs rw_param will contain the buffers and parameters required to read and write through I2C combined format

Returns

0 on SUCCESS if request == M2MB_I2C_IOCTL_SET_CFG or request == M2MB_I2C_IOCTL_GET_CFG; number of written Bytes on SUCCESS if request == M2MB_I2C_IOCTL_RDWR and the function is used only for writing; number of read Bytes on SUCCESS if request == M2MB_I2C_IOCTL_RDWR and the function is used only for reading or both for writing and reading; -1 on FAILURE;

Example of config

M2MB_I2C_CFG_T i2c_data;
i2c_data.sdaPin = 2; //SDA pin on GPIO_02
i2c_data.sclPin = 3; //SCL pin on GPIO_03
i2c_data.registerId = 0x04; //register to write to or to read from: 0x04
i2c_data.rw_param = (M2MB_I2C_RDWR_IOCTL_DATA*) m2mb_os_malloc( sizeof(M2MB_I2C_RDWR_IOCTL_DATA) );
 
Ret = m2mb_i2c_ioctl( fd, M2MB_I2C_IOCTL_SET_CFG, (void *)&i2c_data );
if ( Ret )
{
  LOG(" m2mb_i2c_ioctl() - I2C FAIL" );
  testErrs = 1;
}

Example of Combined mode write access

//write 2 bytes starting from register 0x04, no read operation
M2MB_I2C_CFG_T i2c_data;
INT32 IICres;
 
i2c_data.registerId = 0x04;
memset( iicbuf_wr, 0x00, 256 );
memset( iicbuf_rd, 0x00, 256 );
 
iicbuf_wr[0] = i2c_data.registerId;  //first send register id
iicbuf_wr[1] = 0xaa;  //data to write in register 0x04
iicbuf_wr[2] = 0xbb;  //data to write to register 0x05
 
msgs[0].buf = iicbuf_wr;
msgs[0].flags = I2C_M_WR;
msgs[0].len = 3; //send 3 bytes, one of address and two of data, to external device
 
i2c_data.rw_param->msgs = &msgs[0];
i2c_data.rw_param->nmsgs = 1; //only writing
IICres = m2mb_i2c_ioctl(fd, M2MB_I2C_IOCTL_RDWR, (void *)&i2c_data);

Example of Combined mode read access

//read 2 bytes starting fom 0x4 register
M2MB_I2C_CFG_T i2c_data;
INT32 IICres;
 
i2c_data.registerId = 0x04;
memset( iicbuf_wr, 0x00, 256 );
memset( iicbuf_rd, 0x00, 256 );
iicbuf_wr[0] = i2c_data.registerId;  //first send register id
 
msgs[0].buf = iicbuf_wr;
msgs[0].flags = I2C_M_WR;
msgs[0].len = 1; //send 1 byte, address, to external device
 
msgs[1].flags = I2C_M_RD;
msgs[1].len = 2; //read 2 bytes
msgs[1].buf = iicbuf_rd;
 
i2c_data.rw_param->msgs = &msgs[0];
i2c_data.rw_param->nmsgs = 2; //both writing and reading
IICres =  m2mb_i2c_ioctl(fd, M2MB_I2C_IOCTL_RDWR, (void *)&i2c_data);

m2mb_i2c_open()

INT32 m2mb_i2c_open	(	const CHAR *	path,
		INT32	flags,
			...
	)

open an I2C device

This function opens a file descriptor to communicate with an I2C device, given its address.

Parameters

[in]	path	Path for the device address, in the format "/dev/I2C-#" where # is in decimal format I2C address is in 8 bit format, where last bit is the R/W flag
[in]	flags	currently unused

Returns

file descriptor on SUCCESS, -1 on FAILURE

#define DEVICEADDR 0x0F  //e.g. the device address reported by device vendor on datasheet
CHAR path[32];
INT32 fd;
 
sprintf(path, "/dev/I2C-%d", DEVICEADDR << 1);
fd = m2mb_i2c_open( path, 0 );
if (-1 == fd)
{
  LOG("cannot open I2C channel");
  return -1;
}

m2mb_i2c_read()

SSIZE_T m2mb_i2c_read	(	INT32	fd,
		void *	buf,
		SIZE_T	nbyte
	)

Read data from a connected I2C device.

This function will try to read the requested amount of data from the specified I2C device. The read operation is performed with a write request for the register on the I2C bus, followed by a second Start Sequence and the read request. The register address for the operation must be previously set with m2mb_i2c_ioctl. Note: the number of read bytes depend on the specific i2c peripheral

Parameters

[in]	fd	File descriptor, returned by m2mb_i2c_open
[in]	buf	destination buffer, previously allocated
[in]	nbyte	length of destination buffer in Bytes

Returns

number of read Bytes on SUCCESS, -1 on FAILURE

#define DEVICEADDR 0x0F  //e.g. the device address reported by device vendor on datasheet
CHAR path[32];
INT32 fd;
M2MB_I2C_CFG_T config;
UINT8 buffer[10];
SSIZE_T i2c_res;
 
sprintf(path, "/dev/I2C-%d", DEVICEADDR << 1);
fd = m2mb_i2c_open( path, 0 );
if (-1 == fd)
{
     LOG("cannot open I2C channel");
     return -1;
}
 
config.sclPin = 3; //use GPIO3 for Clock
config.sdaPin = 2; //use GPIO2 for Data
config.RegisterId=0x1F; //Slave Device Register address to be accessed
                        //(either in read or write operations)
m2mb_i2c_ioctl(fd, M2MB_I2C_IOCTL_SET_CFG, (void *)&config);
 
//do communication with I2C device
i2c_res = m2mb_i2c_read(fd,buffer,5); //try to read 5 bytes from the slave device.
 
m2mb_i2c_close(fd);

m2mb_i2c_write()

SSIZE_T m2mb_i2c_write	(	INT32	fd,
		const void *	buf,
		SIZE_T	nbyte
	)

Write data to a connected I2C device.

This function will try to write the requested amount of data to the specified I2C device. The register address for the operation must be previously set with m2mb_i2c_ioctl.

Parameters

[in]	fd	File descriptor, returned by m2mb_i2c_open
[in]	buf	input buffer, previously allocated
[in]	nbyte	number of bytes to be written, in Bytes

Returns

number of written Bytes on SUCCESS, -1 on FAILURE

#define DEVICEADDR 0x0F  //e.g. the device address reported by device vendor on datasheet
CHAR path[32];
INT32 fd;
M2MB_I2C_CFG_T config;
UINT8 buffer[10];
SSIZE_T i2c_res;
 
sprintf(path, "/dev/I2C-%d", DEVICEADDR << 1);
fd = m2mb_i2c_open( path, 0 );
if (-1 == fd)
{
     LOG("cannot open I2C channel");
     return -1;
}
 
config.sclPin = 3; //use GPIO3 for Clock
config.sdaPin = 2; //use GPIO2 for Data
config.RegisterId=0x1F; //Slave Device Register address to be accessed
                        //(either in read or write operations)
m2mb_i2c_ioctl(fd, M2MB_I2C_IOCTL_SET_CFG, (void *)&config;
 
//do communication with I2C device
buffer[0] = 0xF2; //set some data
i2c_res = m2mb_i2c_write(fd,buffer,1); //try to write 1 byte on the slave device register.
 
m2mb_i2c_close(fd);