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Documentation

Relevant links

https://anneryeo.github.io/DS169_IOT/ -- DHT11 Sensor Dashboard Visualization

Personal Notes

• For breadboards...
  • Each row is 123, each column is A to J, from center trench.
  • When there is a wire plugged in A-1, B to J-1 will be electrically connected.

Hardware

• ESP32-WROOM-32 - 3.3V logic
• DHT-11 Sensor - 3.3V
• MQ135 - 5V (derive from micro-USB/C from VIN/5V/VU pin from ESP32 board)

How to wire

When using a breadboard, which I am, it will be female-male jumper wires connected to the corresponding row of the male pin of the ESP32 board. What I did was to color-code the wires for its purposes. Which means, GND wires = black, or something.

DHT11 Pin	Wire to ESP32 Pin	Purpose
VCC(or +)	3V3 (Power) : Red	Provides 3.3V power.
GND(or -)	GND (Ground) : Blue	Completes the circuit.
DATA(or OUT)	GPIO 4 (D/P 4) : Green	Sends the digital temperature/humidity signal.

MQ135 Pin	Wire to ESP32 Pin	Purpose
VCC	VIN (or 5V) : Red	Provides the 5V needed for the heating element.
GND	GND : Blue	Completes the circuit.
A0(Analog Out)	GPIO 34 (D/P 34) : Yellow	Sends the raw analog voltage based on gas concentration.
D0(Digital Out)	Leave Disconnected	Only used for simple high/low triggers; we need the raw analog data for$eCO_2$math.

Arduino

1. Go to Sketch -> Include Library -> Manage Libraries
   1. DHT Sensor Library by Adafruit
   2. Install all dependencies (like Adafruit Unified Sensor)
2. Board = DOIT ESP32 DEVKIT V1
3. Tools -> Port; Select COM port according to your USB-C
4. Set Serial Monitor to 115200 baud
5. Use test.ino in \backend
   1. Upload test.ino code
   2. When connecting, click Boot (not EN)
      1. Error 1: Change Upload Speed from Tools -> Upload Speed -> 921600 to 115200
         1. Cause the cheap duplicate ESP32-WROOM can't handle the massive amount of data transfer at the speed that Arduino can do.
      2. Unplug MQ-135 5V Wire if error during test upload. This happens sometimes because of the power hunger of the sensor.
      3. "ERROR: Write failed, written flash region is empty." : Change Board to ESP32 Dev Module -> Change Flash Mode to DIO from default QIO; double check upload speed to still be 115200.
      4. Unplug 5V if persistent invalid header error when all settings, wires are correct. Sometimes it's just a power supply problem.

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Google Sheets Integration (No MQTT / No Node-RED)

This replaces the old MQTT → Node-RED pipeline with a direct ESP32 → Google Sheets approach.

Architecture

ESP32 (Ambify_GoogleSheets.ino)
   │  HTTPS GET with sensor params
   ▼
Google Apps Script (GoogleAppsScript.gs)
   │  Appends row to spreadsheet
   ▼
Google Sheets ("Ambify Sensor Data")
   │  Also serves as a JSON API
   ▼
React Native App (useSensorData hook)
   │  Polls every N minutes
   ▼
MainDashboard / ProductivityScreen

Setup Steps

1. Google Sheets + Apps Script

1. Create a new Google Sheet — name it "Ambify Sensor Data"
2. Add headers in Row 1:

   A	B	C	D
   Timestamp	Temperature (°C)	Humidity (%)	CO₂ (ppm)

3. Go to Extensions → Apps Script
4. Delete default code, paste entire contents of backend/GoogleAppsScript.gs
5. Deploy → New deployment
   • Type: Web app
   • Execute as: Me
   • Who has access: Anyone
6. Copy the deployment URL (looks like https://script.google.com/macros/s/XXXX/exec)

2. ESP32 Firmware

1. Open backend/Ambify_GoogleSheets.ino in Arduino IDE
2. Fill in at the top:
   • WIFI_SSID — your WiFi network name
   • WIFI_PASSWORD — your WiFi password
   • GOOGLE_SCRIPT_URL — the deployment URL from step 1.6
3. Adjust LOG_INTERVAL_MINUTES (default: 2 minutes)
4. MQ135 simulation is ON by default (SIMULATE_MQ135 = true)
   • Edit SIMULATED_CO2_VALUES[] to demo any ppm levels
   • Set to false when you have a working MQ135
5. Upload: Board = ESP32 Dev Module, Flash Mode = DIO, Upload Speed = 115200

3. React Native App

1. Open src/utils/sensorData.ts
2. Set GOOGLE_SCRIPT_URL to the same deployment URL
3. Adjust POLL_INTERVAL_MS if needed (default: 2 minutes)
4. That's it — MainDashboard and ProductivityScreen will auto-switch to live data

Simulation Quick Reference

Where	What	How
.ino line ~68	SIMULATED_CO2_VALUES[]	Add/edit ppm values the ESP32 cycles through
.ino line ~78	SIM_TEMPERATURE / SIM_HUMIDITY	Override DHT11 for desktop demo
.ino line ~43	LOG_INTERVAL_MINUTES	Change logging frequency (1–5 min)
ProductivityScreen.tsx	PRACTICE_LEVELS array	Demo values when no live data
MainDashboard.tsx	PRACTICE_LEVELS array	Demo CO₂ values when no live data
co2Utils.ts	getCO2UIData() thresholds	Change color/label breakpoints

Verifying It Works

1. After uploading to ESP32, open Serial Monitor (115200 baud)
2. You should see WiFi connection, then readings + HTTP 200 responses
3. Check your Google Sheet — new rows should appear every N minutes
4. In the app, the circle (MainDashboard) and bento cards (ProductivityScreen) will update from the sheet