Temperature Controller Module

• 1. Installation
• 2. System Objective
• 3. System Components
• 4. System Interface
• 5. System Operation
• 6. System Design
• 7. MISRA-C: 2004 Compliant

1. Installation

The Software used in this project is Proteus Design Suite, it is a proprietary software tool suite used primarily for electronic design automation.

It's better to use the same version of the simulation or a newer version to open the simulation file without any problems. We used Proteus 8.10.

Download Link: Proteus 8.10 SP3

2. System Objective

Temperature Controller Module is a System designed to provide Temperature Control Functionality in different states. The system provides the ability to reach a targeted temperature called SET_TEMPERATURE which is determined by a user interface.

To simulate the heating process, the system uses a Voltage Control Module (PWM) with a selected Intensity controlled by the user.

System states are being displayed to the user during the run-time, so the user can know the current system state and which process is running in the background.

3. System Components

The system is composed of the following components:

• Microcontroller: ATmega32 Microcontroller
• LCD: Display Target and Current Temperatures and System States
• Keypad: 4x3 keypad for user Interface and control states switching
• TC72 : Temperature Sensor Module Based on SPI Protocol
• Potentiometer: A Calibration Resistor used as the Heater Intensity Controller
• PWM to Voltage Converter: Converts the PWM to a targeted decimal voltage

4. System Interface

Below is the System Design Interface on Proteus 8.10.

On the left side: all the user interactions are collected; LCD Display, Keypad, Potentiometer and System State LEDs.

On the right side: the backbone of the System is collected; ATmega32 Microcontroller, TC72 Temperature Sensor and PWM to Voltage Converter.

For the sake of testing, we added an Oscilloscope to simulate the Heating Process when Enabling/Disabling the PWM with different Duty Cycles.

5. System Operation

In this section we will describe the flow-work of the system from the beginning of the simulation to the end for each state.

Start Simulation

When you run the simulation you will see an animation of "Welcome" word, starts from the right side of the screen till the left side forth and back 3 times. Then the Idle Screen is displayed with some default values such as the target temperature 25 C° and the current system state. This is the STANDBY state, the first state that System starts with.

System States

The System Operates in 4 different States:

STANDBY STATE

• At this state, the system does nothing, just the LCD and the Keypad are functioning. The system waits the user to enter the target temperature, Aka. SET_TEMPERATURE which the system will try to reach when it starts the operation.

• To switch to the second state, the user shall press '#' key on the Keypad.

• Here's an animated GIF from the demo:

  

OPERATION STATE

• At this state, the other modules such as Temperature Sensor, Potentiometer and the PWM shall start their functionalities.

• The Current Temperature received from the temperature sensor is updated periodically every 200ms and is compared with the target temperature to calculate the Target Voltage which will be applied to the PWM to Voltage Converter. The heater is currently working and the oscilloscope is displaying the square wave in a 1KHz frequency

• To simulate the increase/decrease in the current temperature in Proteus, you have to adjust the value in the sensor by yourself via the '↑' or '↓' arrow in the sensor.

• When the difference between the target and current temperature is ≤ 5, this indicates that the heater has done its job and reaches the NORMAL STATE.

  

NORMAL STATE

• At this state, the system has reached the desired target temperature.

• The heater is not functioning now, thus the PWM output voltage is 0, no operation is running.

• The user can switch to STANDBY STATE by pressing '#' key on the keypad.

• If the system didn't follow this behavior, it will switches to the ERROR STATE

  

ERROR STATE

• At this state, we have 2 error cases:

  1. The system has reached the NORMAL STATE and turned off the heater, but the current temperature is still increasing, which indicates that there is a problem in the heater.

  2. The system failed to reach the target temperature in a 3 minutes, which also indicates that there is a problem and the heater is not working.

• You have to POWER OFF the whole system to exit this state as the keypad is not working anymore and nothing is functioning.

  

STATES Diagram

We draw this diagram to describe the system states in a better way. This diagram shows the relations between the states, how the system can switches between states and which components are functioning at each state.

6. System Design

We followed a Layered Architecture to best design our System to meet the User's needs. The Layers Starts from the Top at our Main Script which is a Higher Manager (Mode Manager), Next come the Lower Managers Heater Control, Display Manager, Scheduler and Temperature Manager. These four Managers are the Process Controllers for the Mode Manager.

Each Manager has a defined set of Tasks:

• Display Manager: Main Controller of the LCD Display Functionalities. Displays both Welcoming Screen, Idle Screen, System States and Temperatures Readings.

• Heater Control: Controls the Heater's Functionalities; Disabling/Enabling the Heater, Heater Intensity Control, System States Check and System State LEDs.

• Temperature Manager: Main Interface to the TC72 Sensor, also responsible for updating the current and target temperatures.

• Scheduler: This is the Timer Manager as most of our tasks are Periodic like reading the sensor's value every 200ms and Updating Heater Intensity every 500ms.

We draw this UML diagram to describe the system design in a better way. This diagram shows the relations between the managers and their dependencies in the whole project.

MISRA-C: 2004 Compliant

We used Code Composer Studio to check for MISRA-C: 2004 rules. The whole project is compliant with this version except 3 warnings we justified them in the code.

Demo Video

We recorded this video to explain the system states, system design, and test the simulation on Proteus.

Here is the video link: Demo Video

Authors

Copyright © 2021, Team #3. Biomedical Engineering Department, Cairo University.