Headphone/Microphone break-out?

Stuart Longland VK4MSL

Hi all,

Silly thought just occurred to me… one sore point with the Raspberry Pi
is that the device provides no audio I/O apart from the PWM audio output.

Now, the UDRC/DRAWS is a big improvement on that, with a decent audio
CODEC chip capable of 192kHz audio. There's 3 line-in channels, a
MICBIAS output, a line-out and a headphone output, all available on the
audio CODEC chip. The mixer is able to do all kinds of routing voodoo.

With such a set-up, whilst of course you won't drive a headset and two
radios off the two ADC and two DAC channels, you could conceivably drive
one radio and one headset with the right routing settings, or use the
headphone output as a monitor.

In applications where you just want something to connect a headset to
your radio for SSB/FM voice, that can be facilitated through the mixer
alone (no latency as it's purely analogue): e.g. if the microphone
hooked to IN3[L+R], you could route IN3L→LOL and IN1L→HPL; or IN3R→LOR
and IN1R→HPR.

You'd then just need a switch to connect your headset either to HPL or
HPR (or both if you want to use the UDRC/DRAWS as a sound card for
music, etc).

Anyway, it was a thought that occurred to me. Maybe in a future design,
a small pin header could expose those pins for those who choose to use them.

Stuart Longland (aka Redhatter, VK4MSL)

I haven't lost my mind...'s backed up on a tape somewhere.