Problem with I2S

[Artem Dmitriev]

Posted on February 27, 2018 at 12:25

Hello!

Our customer has a problem:

'We tried to connect m66-ds modem to STM32F207VE, scheme in attachments. I2S initalization code is generated in CubeMX. We tried to work with I2S interface using interrupts, it worked but eventually synchronization left (synchro impulse and start of data packet are diverged in time).

There are solutions of the problem in errata, but they didn't help us.'

[waclawek.jan]

Posted on February 27, 2018 at 17:08

synchronization left (synchro impulse and start of data packet are diverged in time)

What is synchro impulse and what is data packet in this particular application?

Do you mean the WS at the beginning of each 16-bit word? But as STM32 is slave here, synchronicity of these two is given by the master, i.e. the modem. Am I overlooking something?

JW

[Artem Dmitriev]

Posted on February 28, 2018 at 07:01

Customer said that STM32 doesn't react on WS from master.

[Artem Dmitriev]

Posted on February 28, 2018 at 09:33

Do you have I2S slave examples for STM32F207?

[waclawek.jan]

Posted on February 28, 2018 at 09:53

Customer said that STM32 doesn't react on WS from master.

That's true. It's the essence of quoted erratum: in the 'F2s and the respective 'classic' 'F4s, the I2S module in slave mode uses the WS input only for initial synchronization, and does that in a dumb way (level sensitive rather than edge sensitive).

This

https://community.st.com/0D50X00009XkW2ISAV

be different in the newer chips, e.g. 'F4

You may also want to examine the working of SPI_SR.FRE and whether and how it can be used for synchronism recovery.

You may also want to look at SAI in those newer devices.

I have no experience with PCM in particular, I used I2S only for 'Philips' I2S.

JW