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Strange behaviour of SAI ports

Question asked by Giuseppe Scarpi on Oct 29, 2019
Latest reply on Nov 3, 2019 by Hui_Ma

Hello everybody!

We are experiencing a strange behaviour with SAI2 and SAI3 on our board.

We use all three SAI ports. All of them are set as master, and generate MCK, BCK and FCK towards external peripherals.

All the SAI take the clock from PLL4.

Circa one reboot every 100, SAI2 and SAI3 stop working. We no longer see FCK and BCK. Moreover, MCK is still present on SAI2 but not on SAI3.

Analysing the register map with the debugger (I examined SAI, IOMUX and CCM), I noted that the "good" and "bad" conditions exhibit no difference in relevant settings.

I suspect that we can be in a condition similar to errata ERR050144, but we don't use the TMR masking. Moreover, all the error flags are zero when the error happens.

I also tried to reset the SAI by toggling the TE and RE bits, with no success.

The fact that SAI1 keeps working let me think that PLL4 is OK.


Has anyone experienced a similar condition? Any suggestion about what we can try?