New Model Development Updates

[Graham72]

Hey All.

I took a bit of time to do the logic for the I2S sound interface over the last couple of days, to prove out the sound system.

Good news is, regular Microbee sound is now working - that is, the 1 bit sound that is driven by a pin of the PIO and normally
connected to a speaker via a driver transistor can be heard via the new arrangement.
Rather than going straight to the speaker, now that signal is routed to the FPGA where it is mixed in with (what will be) wave sound
from the new FIFO buffers and presented on the I2S sound interface to an external stereo DAC for line level output and internal speaker driving.
The I2S connection also goes to the HDMI interface for sound over HDMI.

What I've done so far is enough to have the normal 1 bit sound working.  I still need to implement the FIFO sound buffers for wave table
stereo sound but the connection into the I2S transmitter section is already there. I also need to program the HDMI interface to enable sound out there.

Still, very happy to have proven out the sound interface.

I did find an 'oopsicle' on the FPGA module where I'd forgotten to connect the PIO Speaker Bit to the FPGA, but I've put a link on the main board
to a 'Reserved' pin on the FPGA module for now.  The main boards (both models) need a couple of small changes anyway, so if I make the change
for the speaker bit there (like I've done with the link on the current version to get it going) then there are no changes required for the FPGA module.

Happy days.

Yay! Progess, link by link. Great to hear! Your dedication is outstanding. I spoke to a former Microbee user from the education field and informed him of the upcoming release.