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SSI TDM Slot Transmit Error

Question asked by Andrew DeLiso on Aug 24, 2015
Latest reply on Sep 16, 2015 by igorpadykov

Hello All,

 

I am working to support the a 4 channel SSI bus to a Wolfson audio chip (WM5102).  The clocks (yellow) and frame sync(green) are being generated by the Wolfson chip.  When I capture the data from the audio interface I am seeing 4 16-bit PCM channels at 44.1KHz as I expect.  The problem is on transmit I see the first frame sometimes leaving in slot 0 and sometimes in slot 1. 

 

I pulled a patch from another post about setting the Tx/Rx Masks, but I am still have the transmit problem. 

I have attached two screen captures showing the measurements of the SSI bus.

 

Software: Linux Kernel 3.0.101 with a modified imx-ssi.c

 

Here is dump of some of the settings:

slots=4,

SCR=00000118,

STCR=0000038d,

SRCR=0000038d

STCCR=0004e300

SRCCR=0004e300

STMSK=fffffff0

SRMSK=fffffff0

When Transmitting:

SSI_SCR 11b

SSI_SIER 100000

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