[Coco] Cartridge Port Sound

[Gene Heskett]

On Sunday 27 December 2015 13:15:28 Darren A wrote:

> I want to connect an IO pin of an AVR micro controller to the SND
> input line on the CoCo cartridge port. The IO pin will be outputting
> PCM audio. Can anyone describe the proper way to do this? The Service
> Manuals mention that it needs to be AC coupled.
>
Yes.  Try a .05 capacitor in series with it, if no bass, try a .5.

But the coco's audio  doesn't know what to do  with PCM audio, so we'll 
need to know the output clocking speed of the AVR, with an eye toward 
using a simple low pass filter to integrate the encoded but digital 
signal into something resembling an analog audio. If its too slow, say 
less that 50 kilohertz for the clock, the filter might get more complex 
than a simple rc rolloff.

> - Darren


Cheers, Gene Heskett
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