1. Closed Loop Temperature Control Circuit with LCD Display Mike Wooldridge ECE 4330 Embedded Systems

2. System Block Diagram

3. Project Description Voltage divider circuit generates heat from current Increased Voltage -> Increased Current -> Decreased Rt Closed loop - Voltage is feedback to the ADC PWM controls fan speed in an effort to keep the temperature constant Push buttons will select the desired temp LCD will display the desired and current temperature

4. Hardware Design

5. Software Design Configure the pulse width modulator Configure the analog-to-digital converter Calculate the error from the feedback to adjust the duty cycle Configure the timer interrupt to update the OCR every 100 ms Set up the switches to select a desired temperature Output of the PWM determines the fan speed Set up an output port to drive the LCD Calculate the actual temperature from the ADC reading and send this value to the LCD

6. What I Need to Do Determine the values I need for R and Rt Find a LCD and driver compatible with the STK500 Build the circuit and experiment with the input voltage and fan speeds Learn to set up and control the LCD Write the C program Test the final circuit with varying values of Vcc and desired temperatures