I2CSCAN(8) BSD System Manager's Manual I2CSCAN(8)NAME
i2cscan -- scan an IIC bus for devices
SYNOPSIS
i2cscan i2cdev
DESCRIPTION
The i2cscan utility scans the IIC bus (iic(4)) specified by i2cdev to determine which addresses respond.
WARNING! Using this utility can access some devices in such a manner as to leave them in an unstable or unusable state. It can also lock up
the entire iic(4) bus. Don't use this utility unless you know what you're doing and can accept all sorts of unforeseen consequences.
EXIT STATUS
The i2cscan utility exits 0 on success, and >0 if an error occurs.
SEE ALSO iic(4)BSD October 6, 2011 BSD
Check Out this Related Man Page
IIC(4) BSD Kernel Interfaces Manual IIC(4)NAME
iic -- I2C generic I/O device driver
SYNOPSIS
device iic
#include <dev/iicbus/iic.h>
DESCRIPTION
The iic device driver provides generic I/O to any iicbus(4) instance. In order to control I2C devices, use /dev/iic? with the following
ioctls:
I2CSTART (struct iiccmd) Sends the start condition to the slave specified by the slave element to the bus. The slave element consists of
a 7-bit address and a read/write bit (i.e., 7-bit address << 1 | r/w). If the read/write bit is set a read operation is initi-
ated, if the read/write bit is cleared a write operation is initiated. All other elements are ignored.
I2CRPTSTART (struct iiccmd) Sends the repeated start condition to the slave specified by the slave element to the bus. The slave address
should be specified as in I2CSTART. All other elements are ignored.
I2CSTOP No argument is passed. Sends the stop condition to the bus. This terminates the current transaction.
I2CRSTCARD (struct iiccmd) Resets the bus. The argument is completely ignored.
I2CWRITE (struct iiccmd) Writes data to the iicbus(4). The bus should already be started. The slave element is ignored. The count ele-
ment is the number of bytes to write. The last element is a boolean flag. It is non-zero when additional write commands will
follow. The buf element is a pointer to the data to write to the bus.
I2CREAD (struct iiccmd) Reads data from the iicbus(4). The bus should already be started. The slave element is ignored. The count
element is the number of bytes to write. The last element is a boolean flag. It is non-zero when additional write commands
will follow. The buf element is a pointer to where to store the data read from the bus. Short reads on the bus produce unde-
fined results.
I2CRDWR (struct iic_rdwr_data) Generic read/write interface. Allows for an arbitrary number of commands to be sent to an arbitrary num-
ber of devices on the bus. A read transfer is specified if IIC_M_RD is set in flags. Otherwise the transfer is a write trans-
fer. The slave element specifies the 7-bit address with the read/write bit for the transfer. The read/write bit will be han-
dled by the iicbus stack based on the specified transfer operation. The len element is the number of (struct iic_msg) messages
encoded on (struct iic_rdwr_data). The buf element is a buffer for that data. This ioctl is intended to be Linux compatible.
The following data structures are defined in <dev/iicbus/iic.h> and referenced above:
struct iiccmd {
u_char slave;
int count;
int last;
char *buf;
};
/* Designed to be compatible with linux's struct i2c_msg */
struct iic_msg
{
uint16_t slave;
uint16_t flags;
#define IIC_M_RD 0x0001 /* read vs write */
uint16_t len; /* msg length */
uint8_t * buf;
};
struct iic_rdwr_data {
struct iic_msg *msgs;
uint32_t nmsgs;
};
It is also possible to use read/write routines, then I2C start/stop handshake is managed by the iicbus(4) system. However, the address used
for the read/write routines is the one passed to last I2CSTART ioctl(2) to this device.
SEE ALSO ioctl(2), read(2), write(2), iicbus(4)HISTORY
The iic manual page first appeared in FreeBSD 3.0.
AUTHORS
This manual page was written by Nicolas Souchu and M. Warner Losh.
BUGS
Only the I2CRDWR ioctl(2) is thread safe. All other interfaces suffer from some kind of race.
BSD June 24, 2014 BSD