ReadMe
MCP2221 I2C bus driver v0.1
=============================
The driver was designed to expose an I2C bus and to be used with i2c-tools
package.

How to use it
=============
1. Please make sure you have the kernel headers
	Open a terminal and type the following:
	on Ubuntu/Debian: 
	"sudo apt-get install linux-headers-$(uname -r)"
	
	on Fedora/Redhat: 
	"sudo yum install kernel-headers-`uname -r` kernel-devel-`uname -r`"

2. Unpack, compile the driver and install it
	Unpack the downloaded archive file into the directory of choice.
	Open a terminal and navigate into the directory created after
	unpacking the downloaded archive file.
	
	Type the following:
	"make modules"
	"sudo make install"

3. Due to the fact that MCP2221 uses HID class (for I2C, ADC, DAC, GPIO, ...),
Linux will load first an HID driver if available (e.g. hidraw). This driver 
takes over the MCP2221 HID interface

4. To make the I2C driver work with MCP2221, execute as root the 
"driver_load.sh" script.
To run the script please type:
	"sudo driver_load.sh"

5. Now, you should have an entry for the I2C bus driver provided by MCP2221

6. You can use the i2c-tools package to exercise the I2C bus or you can 
develop your own application.
	
	To install the i2c-tools package
	Open a terminal and type the following:
	on Ubuntu/Debian:
	"sudo apt-get install i2c-tools"
	
	on Fedora/Redhat:
	"sudo yum install i2c-tools"

Exercising the I2C bus
======================
- The "i2c-tools" package allows the user to easily interact with the 
I2C bus provided by the MCP2221 I2C-bus driver

Here are a few example commands:
	"sudo i2cdetect -l"
	
The output of this command should be something like:
	i2c-0	i2c       	i2c-mcp2221 at bus 002 device 003	I2C adapter

IMPORTANT
=========
In this case, the MCP2221 board is mapped as I2C bus 0. In your system 
you might have other I2C busses besides the one provided my MCP2221.
Please check the output of the "sudo i2cdetect -l" and select the bus 
number assigned to your MCP2221 board(s).
The examples below assume the MCP2221 board is assigned to I2C bus 0.

To detect the I2C slave chips attached to the MCP2221 you can type:
	"sudo i2cdetect -y 0"
	
The output should show the address of the detected I2C slave chips:
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- 48 49 -- -- -- 4d -- -- 
50: 50 51 52 53 54 55 56 57 -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
	
Note!
	In this example we've used a PICkit Serial I2C Demo Board.
	The detect addresses are those of the I2C slave chips present on 
	this board (24LC08, MCP9800, MCP3221, TC1321, MCP23008)
	
Example commands to use with the MCP23008 I/O expander
=======================================================
	This is a simple "visual" example on how to use the MCP23008 I/Os.
	The I/O pins are connected to 8 LEDs. We will make all the I/Os as 
GPIO outputs and then we will send a hec value to the MCP23008's I/O 
port, thus showing a nice LED pattern.
	Please type:
	
	"sudo i2cset -y 0 0x20 0x00 0x00 b"
	The above command will set the MCP23008's GPIO port as all outputs
	
	"sudo i2cset -y 0 0x20 0x0A 0x55 b"
	This command will output a hex value of 0x55 to the port. All the 
LEDs whose corresponding bit is set to 1 will be lit. Instead of "0x55" 
you can try any other byte value

	To get a snapshot of all the registers within MCP23008 you can type:
	"sudo i2cdump -y -r 0x00-0x0A 0 0x20 b"
	
	You should see an output such as:
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 00 00 00 00 00 00 00 00 55 55                   .........UU     

More documentation on the "i2c-tools" can be found at the below links:

	http://www.lm-sensors.org/wiki/i2cToolsDocumentation
	http://elinux.org/Interfacing_with_I2C_Devices

- You can create your own applications to exercise the I2C bus provided
by the MCP2221 I2C driver

Known limitations
=================
- The driver only supports I2C reads or writes of up to 60 bytes
- Repeated start not implemented in the driver

To do
=====
- implement longer I2C reads/writes of up to 65535 bytes
- implement native SMBus operation support using MCP2221's native capabilities
- add support for GPIO and other MCP2221 capabilities (ADC, DAC, ...)