AnsweredAssumed Answered

STM32F4 I2S Frame Error

Question asked by conrey.rick on Apr 24, 2014
Latest reply on Apr 25, 2014 by conrey.rick
I am having trouble using I2S to connect an audio codec, CS42L55, to the STM32F405. When I configure the STM32F4 to be in MasterTX mode, the codec reports that there is a clock ratio error. With an oscilloscope, I measure my MCLK signal at 12MHz and the LRCK measures at 48kHz, and I believe I have set the codec accordingly to give me a ratio of 250.  I receive no output from the codec on the SDOUT line, and I see 32 clock changes on the SCK line between LRCK changes.

When I configure the STM32F4 in SlaveTX mode, I create a MCLK signal for the codec using a timer and measure the clock signal at 6MHz. The codec then creates and sends the LRCK and SCK signals.  I measure LRCK at 48kHz and this time I only count 31 clock changes on the SCK line between LRCK changes.  This time I am able to receive output on SDOUT and send output that I can hear on SDIN, but since I am missing that one clock tick on SCK the data I get from SDOUT is distorted -- it seems to be shifting circularly as more data comes in.  The STM32F4 reports a frame error, which seems to make sense.

The CS42L55 codec has a fixed output from the ADCs of 24bits and has a variable input which I am sending 24bits.

Has anyone ever experienced something similar or have ideas on how to fix this?  I have attached my configuration code with both my master and my slave configurations. Let me know if you need more of my code.

Attachments

Outcomes