SmartDomik & Picos
SmartDomik
Hey Picos, I was thinking about upgrading our kitchen’s energy usage. What if we built a DIY smart thermostat that runs on open‑source firmware and lets us monitor power draw in real time? We could tweak the algorithms for efficiency and maybe even add a small solar‑charge backup. Sounds like a fun project to blend automation with a bit of hardware hacking. What do you think?
Picos
Nice idea, no need for proprietary thermostats, just grab a ESP32, some INA219 for power sense, throw in a solar charge controller, write your own firmware, tweak the PID loop, and watch the real‑time graph on your phone. We’ll swap the stock AC‑only logic for a hybrid model, but don’t forget to keep the OTA updates on, keep it open source, and label the breadboard “BRAIN” so you can see the chaos later. Let’s make it a demo for the community, then. Ready to code?
SmartDomik
Sounds like a solid plan. First, let’s sketch the block diagram: ESP32 on the breadboard, INA219 hooked up to measure the line side of the charger, a buck‑converter to feed the ESP32, and the solar charge controller feeding the mains side when the panels are on.
1. Wire the INA219 to the ESP32’s I2C bus – 3.3V logic, pull‑ups, 0.1µF decoupling.
2. Connect the charge controller’s PV and battery outputs to the INA219, then to the buck‑converter.
3. Flash a base firmware: OTA enabled, WiFi manager, basic REST API.
4. Build the PID loop in the main loop: read power, calculate error versus setpoint, adjust PWM on the buck‑converter.
5. Add a small OLED or push data to a simple MQTT broker, then a mobile app that plots the live curve.
6. Keep the code in a public repo, add a “BRAIN” label on the board so the community can see the chaos and suggest tweaks.
Let me know which parts you want the most help with, and we can get the first build running in a couple of days.
Picos
Nice diagram, let’s crush it.
1. Wire the INA219 first—pin‑out, pull‑ups, 0.1µF decoupling, double‑check the I2C address.
2. Hit the firmware boot‑strap: OTA + WiFi manager + REST stub, that’s the skeleton.
3. Once that’s up, drop the PID into the loop, hook PWM to the buck‑gate, tune on the fly.
4. Add the OLED or push to MQTT, that’s just a payload wrapper.
You pick the first step; I’ll give you the snippet for the INA219 driver and the OTA init. Let’s get the breadboard alive!
SmartDomik
Great, let’s tackle the wiring first.
1. Connect VCC on the INA219 to the ESP32’s 3.3V rail.
2. Connect GND to the ESP32 ground.
3. Tie SDA to GPIO21, SCL to GPIO22 – that’s the default I2C on most dev boards.
4. Place two 10 k pull‑ups from SDA and SCL to 3.3V.
5. Add a 0.1 µF ceramic capacitor close to the INA219 between VCC and GND for decoupling.
6. If you need a different I2C address, pull A0 to VCC or GND; the default is 0x40.
Once that’s set up, give me the driver snippet and the OTA init code and we’ll move on to the boot‑strap. Keep the breadboard labeled “BRAIN” so we can document the chaos later. Let's get that sensor talking!
Picos
```cpp
/* ----- INA219 driver (simplified) ----- */
#include <Wire.h>
#include "Adafruit_INA219.h"
Adafruit_INA219 ina219;
void setupINA() {
Wire.begin(21, 22); // SDA=GPIO21, SCL=GPIO22
if (!ina219.begin()) {
Serial.println("INA219 not found");
while (1);
}
ina219.setCalibration_32V_2A(); // 32V, 2A range
}
float readPower() {
float busvolts = ina219.getBusVoltage_V();
float current = ina219.getCurrent_mA() / 1000.0; // A
return busvolts * current; // W
}
```
```cpp
/* ----- OTA init with WiFiManager ----- */
#include <WiFi.h>
#include <ESPmDNS.h>
#include <ArduinoOTA.h>
#include <WiFiManager.h> // https://github.com/tzapu/WiFiManager
void setupOTA() {
WiFiManager wm;
if (!wm.autoConnect("BRAIN-PROXY")) { // fallback portal
Serial.println("Failed to connect");
ESP.restart();
}
ArduinoOTA.setHostname("brianthermostat");
ArduinoOTA.onStart([](){ Serial.println("[OTA] Start"); });
ArduinoOTA.onProgress([](unsigned int progress, unsigned int total){
Serial.printf("[OTA] %u%%\r", (progress / (total / 100)));
});
ArduinoOTA.onEnd([](){ Serial.println("\n[OTA] End"); });
ArduinoOTA.begin();
MDNS.addService("http", "tcp", 80); // optional mDNS
}
```
Just drop those into `setup()` after your serial init, hit the board and you’ll have the sensor up and OTA ready. BRAIN is now ready for chaos!
SmartDomik
Looks solid—just add `setupINA()` and `setupOTA()` to your `setup()` after initializing Serial, and you’ll have power sensing and OTA all on. Once the ESP boots, you should see the INA219 reading on the serial monitor and the OTA portal if you hit Wi‑Fi reset. Next up, plug in the buck converter PWM pin, then we can drop in the PID loop. Let me know when you’re ready for that.