This looks doable, normally the I2S and S/PDIF signals are referenced to an internal PLL, but there is a register that bypasses the PLL with a clock from an external pin. There are two of these external clocks, one of which connects to the EDM connecttor. On the wand carrier board that clock is not connected to anything so it looks like we can use it to feed in the external oscilator clock.
The only problem with this is that it is not clear where the bypass happens, it's not shown in the block diagram. It could either be a bypass of just the PLL, in which case we need to set the PLL dividers to 1 (normally the PLL runs at 630MHz), OR it might be injected after the dividers, in which case we don't care about the divider values. We still need a pin to control the external clock mux. There is nothing specific for this in the audio subsystem, it is going to have to a GPIO, of which there are plenty. I just have to choose one which is active in the IO mux mode we will be running in. (of which I don't know yet). This is the one unclear issue preventing me from starting a board layout right now. I think I can figure this out from finding a specific signal that IS being used, find out what pin its physically on and then determine which IO mux mode has to be in play for that function to be on the pin. With the mux mode I can then choose a GPIO that is active in that mode. In any case it looks like there is a way to get an external clock into the chip and it is on the EDM connector. So I think the wandboard is good to go as a base hardware platform. John S. ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=97881 _______________________________________________ discuss mailing list discuss@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/discuss
