Finally did a bit of work on my instrument today! I think the last time I touched it was in May? Sheesh.

The solenoid driver module breakout for it has been sitting partly done for much longer than that, though. I’ve had this nagging feeling that the way I decided to set it up was wrong. Today I decided to change part of it: rather than have the mosfet driver boards connect to a GPIO breakout for my laptop (which I was – still am – pretty excited about) I started testing it with an esp32-S3 – one of the teeny little ones seeed makes.

The GPIO breakout would save writing some code (I’m all for that generally!) and let me drive the solenoids and motors directly from the built-in computer via USB. I’ve changed my mind about actually embedding the computer into the contraption itself, though. I tried to leave lots of space for airflow, but despite that the mainboard tends to get hot and the fans pretty much stay running full speed when it runs.

Rather than embed the main computer (my old laptop mainboard in a standalone case) in the thing itself, I’m planning to use a raspberry pi (for now – later I’d like to make something dedicated with another esp32 + a couple external DACs) and stream audio from my laptop to it over wifi instead.

The entire system is meant to eventually be a loose collection of networked nodes of esp32s and computers funneling audio over wifi in a scheme I’m working out, and sending control signals via wifi via UDP. To that end, I figured it made more sense to just start with wifi for the solenoid/motor module and did some testing today sending nonsense via UDP to it and triggering the solenoid module.

I didn’t measure latency but it seemed to work pretty well. The seeed esp32-S3 supports connecting a rechargeable battery to it directly, as well as charging it via USB-C, so I might just stick a little battery onto the unit instead of powering it from the main battery banks.

I still need to wire up all the rest of the breakout connections (16x going to the solenoid/motor connectors and then I think a row of headers for the signalling connections from the microcontroller, since the wires soldered to the driver board are solid core and should be OK to just plug into a row of headers hopefully) and figure out where to fit the battery for the esp32…

The worrying wrinkle I ran into today after soldering up the final power connections on the board though was that these 12v -> 5v converter components I’ve never used before get pretty hot when I’m routing through them to send 5v to the breakouts. I have no idea if that’s normal…

This is probably a good chance to try to improve my (non-existent) debugging skills and see if I can figure out if there’s actually something wrong with the way I’ve wired things up! It’s likely! I should have tested the components before I soldered them into the module haha, oh well. If I really need to replace them with something else thankfully that bit is fairly malleable – the boards attached to them are just screwed in via standoffs, and there’s enough slack on the connections it shouldn’t be too bad to snip them out and patch in something else if need be.

Here’s hoping!

Also: I forgot how nice the arduino library APIs are. I got into the habit of avoiding it I guess because I hate the IDE, but things like arduino-cli and platformio now make the IDE unnecessary. I set up the seeed via platformio and made a little test sketch that wiggles one of the GPIO pins when it gets anything via UDP. The Wifi/UDP interfaces are so clean and nice it’s lovely. Here’s the little sketch and the platformio config:

#include <Arduino.h>
#include <WiFi.h>
#include <WiFiUdp.h>

WiFiUDP Udp;

char packetBuffer[255];
int status = WL_IDLE_STATUS;

void setup() {
    pinMode(LED_BUILTIN, OUTPUT);

    pinMode(D0, OUTPUT);

    digitalWrite(LED_BUILTIN, HIGH);

    WiFi.begin("WCC-Temp", "makeithappen");

    while(status != WL_CONNECTED) {
        status = WiFi.status();
    }

    Udp.begin(2390);

    Serial.begin(9600);
    while(!Serial) { }

    digitalWrite(LED_BUILTIN, LOW);
    digitalWrite(D0, LOW);

    delay(5000);

    IPAddress ip = WiFi.localIP();

    Serial.println("IP:");
    Serial.println(ip);
}

void loop() {
    digitalWrite(LED_BUILTIN, LOW);
    int packetSize = Udp.parsePacket();
    if(packetSize) {
        int len = Udp.read(packetBuffer, 255);
        if(len > 0) {
            packetBuffer[len] = 0;
            digitalWrite(LED_BUILTIN, HIGH);
            digitalWrite(D0, HIGH);
            delay(1000);
            digitalWrite(D0, LOW);
            Serial.println(packetBuffer);
            digitalWrite(LED_BUILTIN, LOW);
        }
    }
}

[env:seeed_xiao_esp32s3]
platform = espressif32
board = seeed_xiao_esp32s3
framework = arduino