phpi2c.php

<?php
/* ------------------------------------------------------------------------------------------------
Copyright © 2016, Viacheslav Baczynski, @V_Baczynski
License: MIT License

PHP IIC Library, v1.0

Simple functions to read from and write to registers on device via I2C bus using i2c-tools.


TODO:
	Define the following variables in your file:
	$block			// Block name for the I2C device on the system
	$i2c_address	// I2C slave address (address of the device)
------------------------------------------------------------------------------------------------ */

# READ FUNCTIONS ----------------------------------------------------------------------------------

function read_register(
 $register	// register in the i2c device
){
	return trim( shell_exec( 'i2cget -y ' . $GLOBALS['block'] . ' ' . $GLOBALS['i2c_address'] . ' ' . $register . ' b' ) );
}

function read_short(
 $reg_msb	// register with most significant byte
){
	$msb = intval( read_register( $reg_msb++ ), 16 );
	$lsb = intval( read_register( $reg_msb ), 16 );
	$val = ( $msb << 8 ) | $lsb;

	$arr = unpack( 's', pack( n, $val ) );
	$dec_val = $arr[1];
	//echo "DEBUG(read_short): " . $dec_val . "\n";
	return $dec_val;
}

function read_ushort(
 $reg_msb	// register with most significant byte
){
	$msb = intval( read_register( $reg_msb++ ), 16 );
	$lsb = intval( read_register( $reg_msb ), 16 );
	$val = ( $msb << 8 ) | $lsb;

	$arr = unpack( 'S', pack( n, $val ) );
	$dec_val = $arr[1];
	//echo "DEBUG(read_ushort): " . $dec_val . "\n";
	return $dec_val;
}

function read_ulong(
 $reg_msb	// register with most significant byte
){
	$msb= intval( read_register( $reg_msb++ ), 16 );
	$lsb= intval( read_register( $reg_msb++ ), 16 );
	$xlsb = intval( read_register( $reg_msb ), 16 );
	$val = ( $msb << 16 ) | ( $lsb << 8 ) | $xlsb;
	$arr = unpack( 'l', pack( N, $val ) );
	$dec_val = $arr[1];
	//echo "DEBUG(read_ulong): " . $dec_val . "\n";
	return $dec_val;
}

# WRITE FUNCTIONS ---------------------------------------------------------------------------------

function write_register(
 $register,	// register address
 $value		// data to be written
){
	shell_exec( 'i2cset -y ' . $GLOBALS['block'] . ' ' . $GLOBALS['i2c_address'] . ' ' . $register . ' ' . $value . ' b' );
}

function write_short(
 $register,	// register address
 $value		// data to be written
){
	$value = $value & 0xFF;
	write_register( $register, $value );
}
?>