making a digital audio recorder, with an ESP32 instead of a DSP.
even though most audio recorder use DSP chips, i chose the ESP32 because its toolchain is opensource, and has a big community around it. i'm using the SGTL5000 audio codec because that's the same codec as in the Teensy Audio Adapter Board, so I can reuse their schematics.
the schematics are coming very soon, i promise :) then i'll try to route it, and send that to a fab
before going into details about my project, i wanted to show you what is inside other audio recorders. a week ago, i bought a Zoom Q2HD and a Zoom Q3HD, both in bad condition (the Q2HD had pretty bad battery corrosion, whereas the Q3HD had a burned PCB…).
there are 3 pcbs inside a Zoom Q3HD :
the main chip here is an Ambarella A5s-CO-RH SoC. it features an ARM core (clocked at 528 Mhz), and all the bells and whistle you'd need to make a video camera (h264 encoder, i2s interface, video dsp). next to the Ambarella chip, there's 1gbit of hynix ddr2 ram. on the other side of the logic board you can see 1gbit of st nand. nice hardware here.
on the i/o board, we have a Wolfson WM8750 codec chip. this chip does the analog/digital conversions. i don't know which protocol is used for audio data in the Q3HD (the WM8750 handles i2s, left-justified and "dsp mode") as i can't boot it properly.
on the same board we'll also see a couple of JRC NJM2100 op-amps. i guess they are used to amplify the microphone capsules.
let me introduce you to my new project.
i bought quite a while ago a lavalier mic (rode lavalier). i've been using it directly plugged to my dslr mic input. as you may guess, this is a pain in the neck because i have to fiddle with meters of cable.
for a while, i was thinking about buying a second-hand audio recorder (e.g. zoom h1 or tascam dr-05), or a wireless mic solution. at some point, i realised that nobody has yet released an open source digital audio recorder. i took that as a challenge.
so here i am : i have not enough experience to build this and a huuuge goal. we'll see if it works, hopefully :)