ADAU1442 READBACK FUNCTION

Hi

This doesn't seem like normal behavior. Are you sure that you are somehow not running into the limits of MIPS processing on the DSP. Is audio coming out correctly? If filters for example come at half the rate. This may mean that you are exceeding the program MIPS.

Please comment.

Miguel

Miguel,

Even if I run in a program debug mode so I can halt the readback function between reads It still gives the same result.

Hello,

How many bytes are you reading when you perform the read?

Dave T

4 bytes

I am not certain how you are doing the read but try this. Send a three byte message with no stop bit, So the chip address with the R/WR bit low (set to write) then the two bytes for the address of the memory location.

Then wait 600us and send a repeated start command with the chip address but this time with the R/WR bit high (set to read) then clock in four bytes. I think you will find this works.

If you look at SigmaStudio you will see that it has a read request followed by a read. Then looking at the I2C data itself you will see the three byte request followed by a delay to give it time to gather the data then the repeated start and the data.

Let me know how this goes.

Dave T

One further bit of information. I inquired with one of the engineers on the project and he thinks the delay is really not needed. That the time it takes for the repeated start byte to transmit is long enough. So you can also try it with no delay, just the repeated start condition just like you would do with an EEPROM. Write the address you want to access, then a repeat start with the read bit set and then read the data. This should work.

Dave T