Introduction

This page shows how to access the MT9P031 registers using i2c-tool in order to read and/or write them.

How to know where your sensor is?

If you didn't know in which i2c address your sensor is you can find it easily by following the next steps:

1. Don't connect your camera module to the board and start it.

2. Once it started run the following command in your board's terminal:

i2cdetect -l

This command will show you any I2C bus available. In our case it will outputs something like this:

i2c-1	i2c       	DaVinci I2C adapter             	I2C adapter

This tell us we have one I2C bus which ID is i2c-1.

3. Once you got the I2C bus name you can get a map of the I2C devices connected to it by running

i2cdetect -y <numerical_id>

where numerical_id is the number that ends your I2C bus's ID. In our case we can run i2cdetect -y 1 and it will outputs the following map:

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- 08 -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

4. Turn off you board, connect the camera module and repeat the process until get the I2C bus map. You will get something like this:

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- 08 -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

We can see now the presence of the camera sensor at the address 0x48, we need this address in order to tell the i2c-tools which device we want to access.