AM4376: McASP with two slave devices

Hi Darush,

This clock configuration will work for McASP in Synchronous Mode, where the receiver is always clocked using the bit clock and frame sync for the transmitter - these can be outputs (master) or inputs (slave).

You have AXR1 and AXR0 under recevier and transmittor. You will need to use 4 separate serializers for 2 in 2 out at the same time. Each serializer can be configured as input or output.

Keep in mind that if you use the AM437x McASP as the clock master, you may not achieve certain audio frequencies with a given oscillator and integer dividers. However, if the codec has a PLL and fractional divider, you can get extremely close to most frequencies.
One of the codecs can then be the master, and you can configure McASP as a sync slave so both transmittor and receiver are clocked from the ACLKX and AFSX pins.

But... the McASP state machines run off of the bit clock, so if it’s not there, you can’t reliably set up the McASP config registers. You cannot provide MCLK to the CODEC without programming the config registers!
To work around this, I've seen a customer use another McASP to provide AHCLKX to the MCLK input of the CODEC.

Or you can just place a LVCMOS oscillator / clk source on the MCLK of the codecs and always use McASP in slave mode. No need to connect AHCLKX.

Make sure to have separate addresibility for each codec to configure one as a master and the other as a slave.

Consider a few resistor population options if you want to experiment.

Let me know your questions.

Regards,
Mark