> On Sep 17, 2025, at 3:57 PM, Adrian Godwin via cctalk <[email protected]>
> 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
