PCM Interface – I2S

PCM Interface is a kind of standard build on the same principles as SPI. The SPI interface can handle the clocked bit-streams, but I2S can also handle the PCM encoding. In simple words I should be able to send/receive voice effortless – just need to get my head around register settings in STM32F405 which is made easier with STM32CubeMX (see Picture) – just a few clicks and you have sample code to play with. Just watch out because not all options are available in CubeMX.

Not sure if this is the correct setting – the PCM_CLK from SIM808 is fixed to 256Khz which is twice the frequency I need for 8000 Hz which is telecom standard (8000 * 16 = 128000) – assuming 1Hz on the clk is 1 bit I am missing something…

This is the issue dealing with various Chinese components – documentation in English is often limited – but we will sort it out.

The M4 is basically so fast that I was prepared to do this protocol the hard way – first time I look into the I2S and how it’s used. We have 2 of these available.

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