Hi Peter,

"It seems to work..." In what way does it seem to work? Usually the way I determine if an interface is working is I try to read back what I written. Write a register, read a register. If the data read back is not what I've written, I've got the chicken vs. egg problem...which failed, the write or read?

Here is another place a scope will help, you can view the interface running at speed, examine the data at each clock and confirm that the correct slave address is written, acks received, ... Otherwise you have to make sure you've got all the error testing built into your I2C code, for example, verify that an ack was received after slave address was sent. Make absolutely sure that your write is correct, and then start working on read.

Do you have any other I2C slaves? EEPROM? Sometimes the slave addresses will conflict... I once had to change my EEPROM because it responded to the same slave address as my Philips RTC chip. If you have other I2C slaves, without conflict, can you access them?

Dennis