Hi, I have studied the OMAP5 docs a little more and the ABE is more or less what the DSP in the OMAP3 could have been used for: shutting down the CPU and running audio functions autonomously.
Here is the block diagram:
Unfortunately this has some consequences: * there are only 3 McBSP ports - we need them all for: Bluetooth, FM-Radio, UMTS modem * the codec port is a McPDM - which is a TI proprietary format (on OMAP3+TWL4030 it was a PCM channel) * the only MCPDM compatible codecs appear to be the TWL6040/6041 * I am not sure if the ABE-Firmware for the "AE" is a binary BLOB or just some control settings - so some Freedom enthusiasts may complain about that
This means: * if we want to use the ABE (to save power while playing sound or phoning around) we must use the TWL604x * if we don't use it we maybe can use the McASP for I2S * if we don't use it we have to write a lot of software to make audio work * if we use the TWL604x it must very likely be placed on the CPU board (HDI/micro via multilayer) - which means we must route audio over the B2B connectors (which isn't a big problem for speakers but maybe for headphone, microphone and line-in) * if we use the TWL604x we can't use the simple potentiometer for loudness control as in the OpenPandora but must do that with buttons and in software (maybe one of the Cortex-M4 cores can control that even if the A15 system hangs?)
Hm. I think this needs much more thoughs and discussions than is urgent for the next Pyra Prototype (which will *not* have the real CPU board, just an adapter to the EVM - so it will not yet have a working audio subsystem).
So I think the best will be to just (temporarily?) add a Class D amplifier (LM4666) for Protoype Version 3 so that we can at least test the speakers in their enclosure.
BR, Nikolaus