Mahmood:

If you have not already done so I would suggest that you make a small loop in your program to loop the write sequence of a single byte. Then carefully check the sequencing of the I2C bus lines to make sure that they work as required. Here are some basic things to make sure to check.

1) Verify that setup of SDA to rise of SCL meets specification.

2) Verify that high width of SCL is enough.

3) Verify that rate of SCL is not too fast.

Next look very carefully at your STOP sequence to make sure it is implemented correctly. If you have this incorrect the write operation may not initiate and thus be rejected by the part. Reads will seem to work becasue the STOP sequence is not used to start the READ! The timing diagram below will show that you should write the i2c_Stop() routine to ensure that it properly sets the conditions going into the STOP generation. In particular look closely at the area I have colored yellow in the picture.



Good luck.

Michael Karas