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Bit Masking 8-bit telephonic data in iMX6

Question asked by Abhijeet Gokar on Feb 25, 2020
Latest reply on Mar 16, 2020 by Abhijeet Gokar



I am using iMx6q and trying to read data from phone input and SLIC IC. The IC is giving proper 8-bit Mu Law data at its DTX pin. The communication protocol between is I2S and is operating with parameters PCLK=512kHz and FSync=8kHz.


The processor is the master, and I am using ALSA subset utilities (aplay.c userspace application C code) to read and write data on the PCM bus. I am able to write the data onto the chip successfully, but read from it is an issue, and the ALSA program gives the error of Broken pipe from Audio interface.


The 32-bit word from the PCM channel should be masked out as a 8-bit data and then loopbacked to the same VoIP, and later sent to some other interface.


If anyone has interfaced telephonic system, and successfully read 8-bit data from it using bit masking, please help me out.


(Please don't share any documentation as a reply. I have been studying every single reference manual of NXP for the past year, and have got idea of SSI, fsl-dai, audio clocking and PCM timing diagrams. I have referred to the ref manual and reached upto here)