The bottle stand that logs the 3am feed.

Do the cloud part before you touch hardware: it has the most unknowns, and you want the token + database ID in hand before you flash.

1. Go to notion.so/my-integrations → New integration, name it "Feed Logger", copy the Internal Integration Secret (starts with ntn_ or secret_).
2. Create a database called Feed Log with these properties:

3. Open the database → ••• → Connections → add "Feed Logger".
4. Copy the database ID, the 32-char hex chunk in the URL before ?.

The load cell's four thin wires map to the HX711's input pads:

Solder the wires straight to those pads, or do what I did: solder header pins to the HX711 and plug it into the breadboard, then run the load-cell wires in from there. Same mapping either way. Keep the joints clean, no bridges.

All on the breadboard for now. Power both the HX711 and OLED from 3.3V.

Two buttons, each wired from a GPIO to GND: the start/stop button on GPIO 25, and the tare/calibrate button on GPIO 26 (the one you hold at boot to calibrate in the next steps).

Open firmware/ in PlatformIO, then:

1. Copy the example config:

cp firmware/src/config.h.example firmware/src/config.h

2. Fill in your details:

#define WIFI_SSID      "YourWiFi"
#define WIFI_PASSWORD  "YourPassword"
#define NOTION_TOKEN   "ntn_..."
#define NOTION_DB_ID   "your32charhexid"
#define GMT_OFFSET_SEC (-5 * 3600)   // your timezone (example: US Eastern)
#define DST_OFFSET_SEC (3600)

3. Build → Upload, open the serial monitor at 115200. You want: HX711 ready, WiFi OK, NTP time synced, Ready.

The firmware can't know how your specific load cell + mount turn force into grams, so you teach it once.

1. With the stand empty, hold the tare/cal button (GPIO 26) while pressing reset → it enters calibration mode and tares the empty platform.
2. OLED: "Place weight: 250 g" → set your known weight down.
3. It reads, computes the calibration factor, and saves it to flash.
4. Back in normal mode: empty ≈ 0 g, your known weight ≈ 250 g.

Prove the whole loop before it ever touches a real bottle:

1. Put a water bottle on the stand.
2. Tap the button → OLED shows "Feeding…" with a live timer.
3. Pour out ~50 mL of water (simulating what the baby drank).
4. Put the bottle back, tap again → OLED shows "Fed ~50 mL".
5. Check Notion: a new row with start / end / duration / volume should appear within a few seconds.

Measure the poured water to confirm the volume lands within ±5 mL.

While you bench-test, print the stand. The one I designed is in Files & models below: download the STLs and print them. Or grab any load-cell scale-stand model on MakerWorld.

Whatever model you pick, it must give the load cell a cantilever mount with an air gap so the beam can flex. Most scale-stand models already do.

Per hardware/assembly.md: the load cell is cantilevered, one end bolted to the base and the other to the platform, with the HX711 close by and the ESP32, OLED, and button placed for one-handed use. Buttoned up, it looks like this.

After mounting, re-verify an empty stand reads ≈ 0 and your known weight still reads right. The mechanical change can shift the tare, so just tap the tare button.

Counter, bottle station, or nightstand: somewhere flat, stable, and near power and Wi-Fi. Add a wipeable coaster on the platform for the inevitable milk drips.

Next bottle: set it down, tap, feed, set it down, tap. Open Notion, and your first real feed is logged, with the right time and volume. If you wired up Telegram, you'll also get a 🍼 Feed logged ping with the volume, duration, and start and end times.