17 Sep
2025
17 Sep
'25
3:12 p.m.
On Sep 17, 2025, at 3:57 PM, Adrian Godwin via cctalk
<cctalk(a)classiccmp.org> wrote:
I presume Parallax stopped building the EMIC2 board through lack of demand.
The components seem to be still available and relatively cheap (about $12
on Mouser for each of the two large chips). The project page includes all
the pcb details but I don't see source or even binary.
A quick test of the github code uses about 8% CPU on a Pi 4 so should be
within range of a Pi 0. The Pi 0 has no audio out and USB is probably the
cheapest way to do it. The built-in (PWM) audio on the Pi4 is dreadfully
noisy so no real loss and alternative audio modules relatively expensive.
You'd soon get to the $55 of the mikroe.
Might be in range of an ESP32, though the big advantage of a Pi is the
extraordinarily good range of support - all the facilities of Linux without
having to write even a monitor.
Note that I said "Pico" which while also a Raspberry product has next to nothing
in common with a Pi, doesn't run Linux, and is far cheaper.
Re audio: I think simple audio DACs are quite cheap, but they have odd interface schemes
(steady bit streams). No trouble at all for the PIO engine in the Pico, though. I was
thinking at one time about using one of those when I needed a control voltage for a VCXO,
but for that the PWM is adequate. Direct PWM audio might also work ok with the PIO since
it could easily do 20 MHz clock rate so for, say, 11 kHz audio that's about 11
significant bits.
paul