Smart Cooking Thermometer App Development

Smart Cooking Thermometer with Auto-Timers

Project Overview:
I need an Arduino firmware + mobile app for a smart cooking thermometer that starts timers automatically when recipe step temperatures are reached.

Hardware Setup (Ready to Code):
- Arduino Nano + HC-05 Bluetooth + MAX6675 Thermocouple
- Wiring:
- MAX6675: Pins D12(SO), D13(SCK), D10(CS)
- HC-05: Pins D2(TX), D3(RX) via SoftwareSerial
- Power: 5V & GND shared

What I Need Built:

1. Arduino Firmware:
- Read MAX6675 temperature every second via SPI
- Send via Bluetooth: `"TEMP:25.5,77.9\n"` (Celsius,Fahrenheit)
- Handle app commands: `"SETTARGET:85,90\n"` (85°C target, 90s auto-timer)

2. Mobile App (Cross-Platform):
- Must work on both iOS and Android
- Bluetooth connection to "SmartChef-Thermo"
- Real-time temperature display with C/F toggle
- Recipe step guidance with auto-timers
- Key Feature: When temperature reaches target → auto-start step timer
- Phone vibration + notification when timer starts/ends

Auto-Timer Feature (Core Requirement):
```
Example Flow:
1. Recipe Step: "Heat pan to 85°C for preheating"
2. App sets target: 85°C with 90s auto-timer
3. When temp hits 85°C → app auto-starts 90s countdown
4. Phone vibrates: "Pan preheated! Timer started"
5. When timer ends → vibrates: "Step complete!"
6. Auto-advance to next recipe step
```

IMPORTANT - Recipe System Scope:
Phase 1: Simple Pancake Recipe Only
- One preloaded pancake recipe with 5-6 steps
- Each step has: target temperature + auto-timer + instructions
- Example steps: Preheat pan, melt butter, cook batter, flip, etc.

Future-Proof Architecture Required:
- Code must be structured to easily add more recipes later
- Recipe data in modular format (JSON array)
- No hardcoding that prevents recipe expansion
- Easy-to-add new recipe steps without code changes

Technical Requirements:
- Platform: iOS (14+) and Android (10+) compatibility
- Bluetooth: Must use compatible libraries for both platforms
- Recipe data stored in separate, editable file/structure
- Each recipe step: `{temp: 85, timer: 90, instruction: "Preheat pan", ingredients: ["butter"]}`
- Scalable design to add 10+ recipes in future updates

Deliverables:
- Complete Arduino .ino project
- Mobile app source code (iOS + Android)
- Modular recipe system (easy to add new recipes)
- Wiring diagram & setup instructions
- TestFlight build (iOS) + APK (Android)

Must pass testing:
- Test with one pancake recipe (all steps)
- Hardware testing: ice water (around 0°C), boiling water (around 100°C)
- 30-minute Bluetooth stability on both iOS and Android

Milestones & Payment:
1. 25%: Basic temperature + Bluetooth working
2. 25%: App displays temp + C/F toggle + pancake recipe (both platforms)
3. 25%: Auto-timer feature complete with pancake steps
4. 25%: Modular system + cross-platform testing + delivery

Timeline: 3-4 weeks (due to cross-platform requirement)
Budget: Can't go higher than $350

Requirements:
- Required: Arduino + Bluetooth experience
- Required: Cross-platform mobile development
- Required: Experience with iOS Bluetooth permissions/implementation
- Portfolio of similar IoT cross-platform projects
- Must demonstrate scalable code architecture

I have all hardware ready. Looking for clean, expandable code that works on both iPhone and Android.

To Apply:
1. Share similar cross-platform Arduino+Bluetooth projects
2. Your estimated timeline
3. Preferred cross-platform framework
4. Experience with iOS Bluetooth compatibility
5. How you'll structure code for easy recipe expansion