Oven Controller on Arduino

Oven Controller using Arduino UNO and Raspberry Pi Pico Integration
with Bluetooth CLI.

Overview

This project implements an oven control system using an Arduino Uno and LM335 temperature sensor, featuring a Bluetooth (BT) command-line interface (CLI) for real-time control via smartphone and a Raspberry Pi Pico integration for performing remote arithmetic calculations.

The oven automatically controls the heater based on a set temperature, provides state indication LEDs, and includes error handling, safety measures, and command validation.

🧾 Example Session

> Proyecto Horno por grupo 4
> TEMP=30
Temperature set to = 30 C
> TIME=10
Time set to = 10 s
> START
Start : ON
Temperature = 28 C
Temperature = 29 C
Temperature = 30 C
Time = 10 s
Temperature = 30 C
Time = 9 s
...
Process finish!

⚙️ System Features

🔧 Main Components

Component	Function
Arduino Uno	Main controller managing temperature, heater, and communication
LM335	Analog temperature sensor (ADC-based)
Bluetooth Module (HC-05 / HC-06)	Wireless CLI communication with smartphone
LED Indicators	Power, Stop/Error, and Temperature Status indicators
Heater (or motor/LED)	Simulated oven heater element
Buzzer	Audible feedback for process end and errors
Raspberry Pi Pico	Performs arithmetic calculations and communicates via UART

🧠 System Behavior

The system operates through three main states managed by a mealy finite state machine (FSM):

🕹️ 1. IDLE

• Default standby state.
• Awaits configuration and commands from the user via Bluetooth.
• Accepts commands.

🔥 2. PRE-HEAT

• The oven starts reading the LM335 temperature through ADC sampling (A5 pin).

• Compares the current temperature to the set point with a ±5°C margin.

• LED indicators:

  • LOW LED → below target range
  • SET LED → within target range
  • HIGH LED → above target range

• Transitions to HEATING once within the target range.

⏱️ 3. HEATING

• The heater remains ON while counting down the configured time.

• Displays remaining time and temperature every second.

• On completion:

  • Heater turns OFF
  • Buzzer emits two short beeps

• If temperature exceeds range:

  • System triggers emergency STOP
  • Buzzer emits three long beeps
  • User must reset or send STOP command to resume.

🚨 Safety & Error Handling

• STOP Command acts as a toggle (latched behavior).

  • Can be triggered at any time or state.
  • Errors automatically trigger a STOP (sets stop = true).

• Invalid Commands or malformed inputs are handled gracefully with error messages.

• Error conditions (like temperature out of range) immediately stop the heater and notify via Bluetooth.

📱 Bluetooth CLI Interface

The Bluetooth module (HC-05/HC-06) is connected via SoftwareSerial (RX: 2, TX: 3). Baud rate: 115200

💬 Supported Commands

Command	Description	Example
TEMP=XX	Set desired temperature (°C)	TEMP=50
TIME=XX	Set heating time (s)	TIME=30
START	Starts heating (only if TEMP and TIME are set)	START
STOP	Emergency stop (toggles ON/OFF)	STOP
SHOW	Displays system status	SHOW
HELP	Lists all commands	HELP
Calcular: Num1 S Num2	Perform calculation via Raspberry Pi Pico	Calcular: 8 + 5

🔢 Raspberry Pi Pico Integration

A bonus feature of this project integrates a Raspberry Pi Pico via UART (RX: 4, TX: 5) to perform simple arithmetic calculations.

📡 Communication Flow

1. User sends: Calcular: Num1 S Num2 (e.g. Calcular: 8 * 4)
2. Arduino transmits the expression to the Pico.
3. Pico computes the result and sends back: 8 * 4 = 32
4. Arduino relays the response to the Bluetooth terminal and prints it in the Python console.

💻 Pico Code Summary

• UART @ 115200 baud, 8N2 configuration.
• Parses received string to identify operator (+, -, *, /).
• Computes result and sends back formatted string.
• Handles malformed inputs or division by zero errors.

🔋 System Timing

TimerOne is configured to trigger every 250 ms for:

• Power LED blinking
• Input reading via Bluetooth

🔔 Buzzer Feedback

Event	Pattern
Process Completed	Two short beeps
Error / Emergency STOP	Three long beeps