[Coco] Project Sneak Peek

[Zippster]

I would think running the output through a low-pass filter and using an op-amp
circuit similar to what the Orch90 uses would give good results with the CoCo
SND input.  Though that is adding several additional components of course.

<https://drive.google.com/open?id=0B1sgl615FlGnVUFVRTdQOWxqTXM>

The 4558 is still produced and available in an SMT package.  It’s just a GP op-amp.

<http://www.mouser.com/ProductDetail/Texas-Instruments/RC4558D/?qs=sGAEpiMZZMuUbyQTl9BuV8ZQTFWR6UNNrsggaFVWj%2f8%3d>

- Ed


> On Jul 19, 2016, at 11:30 PM, Darren A <mechacoco at gmail.com> wrote:
> 
> On Tue, Jul 19, 2016 at 3:31 PM, Nick Marentes wrote:
> 
>> On 20/07/2016 6:43 AM, Zippster wrote:
>> 
>>> With the addition of an analog low-pass filter, yes.
>>> 
>>> Otherwise they are square waves.
>>> 
>>> - Ed
>>> 
>> 
>> I assume that the PWM functionality is built into the microcontroller for
>> the ability to control things like stepper motors
>> 
>> Sounds cool but I wonder how many CoCo enthusiasts would actually do this.
>> 
>> Is there an option in the controller to vary the amplitude of the PWM or
>> better still, a DAC to dump data from the RAM to the sound output for
>> enhanced game sounds?
>> 
>> I also assume that any PWM sound will not be mixed with the CoCo's 6-bit
>> sound.
>> 
>> (So many questions.)    :)
>> 
> 
> 
> 
> Sound generating hardware/software is not my area of expertise.  I just
> adapted the arduino code referenced below so it could play samples from
> files on an SD card instead of from the MCU flash memory:
> 
> <http://playground.arduino.cc/Code/PCMAudio>
> 
> The SND input on the CoCo cartridge port is not mixed with output from the
> 6-bit DAC, but can be mixed with the single-bit sound output.
> 
> 
> - Darren
> 
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco