STM32 Based Temperature Controlled Fan Simulation Design

Hello everyone, today I want to share an interesting temperature-controlled fan simulation project. This project simulates a temperature control system in a real working environment, detecting ambient temperature through a temperature sensor and automatically controlling the fan speed. The entire system is simple and practical, making it perfect for STM32 beginners to practice.

Hardware Circuit Design

Main hardware components:

• STM32F103C8T6 Microcontroller (Main Control)
• LM35 Temperature Sensor
• L298N Motor Driver Module
• DC Motor (Fan)
• LCD1602 Display
• Button Module

Key points of circuit design:

• ADC channel PA0 connected to LM35 for temperature signal acquisition
• PWM output port PA8 controls motor speed
• LCD1602 is connected using a 4-bit data line
• Independent buttons connected to PB1, PB2 for adjusting temperature threshold

STM32 Configuration and Program Design

1. Main Peripheral Configuration

// ADC configuration
void ADC_Config(void)
{
    ADC_InitTypeDef ADC_InitStructure;
    // ADC1 configured in independent mode
    ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
    // Disable scan mode
    ADC_InitStructure.ADC_ScanConvMode = DISABLE;
    // Continuous conversion mode
    ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
    ADC_Init(ADC1, &amp;ADC_InitStructure);
}

// PWM configuration
void TIM_PWM_Config(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;
    
    // Configure time base unit
    TIM_TimeBaseStructure.TIM_Period = 999;
    TIM_TimeBaseStructure.TIM_Prescaler = 71;
    TIM_TimeBaseInit(TIM1, &amp;TIM_TimeBaseStructure);
    
    // Configure PWM channel
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OC1Init(TIM1, &amp;TIM_OCInitStructure);
}

2. Temperature Acquisition Processing

float Get_Temperature(void)
{
    u16 adcValue;
    float temp;
    
    // Start ADC conversion
    ADC_SoftwareStartConvCmd(ADC1, ENABLE);
    // Wait for conversion to complete
    while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC));
    
    adcValue = ADC_GetConversionValue(ADC1);
    // LM35 temperature calculation formula: 10mV/℃
    temp = (float)adcValue * (3.3 / 4096) * 100;
    
    return temp;
}

3. Fan Control Algorithm

void Fan_Control(float temp)
{
    uint16_t pwmValue;
    
    // Temperature range control
    if(temp &lt; LOW_TEMP)
    {
        pwmValue = 0;  // Stop
    }
    else if(temp &lt; MID_TEMP)
    {
        pwmValue = 500;  // 50% speed
    }
    else
    {
        pwmValue = 999;  // 100% speed
    }
    
    TIM_SetCompare1(TIM1, pwmValue);
}

Proteus Simulation Settings

1. Simulation Device List

• STM32F103C8
• Virtual Terminal (Displays Temperature)
• DC Motor
• LM35
• Power Module

2. Key Settings

• LM35 output port connected to PA0 of STM32
• Motor driver output connected to PA8 of STM32
• Clock set to 72MHz
• Add HEX file of STM32 program

Testing Plan

1. Temperature Detection Test

• Use Proteus’s Interactive Temperature Source
• Verify the accuracy of ADC sampling values

2. PWM Output Test

• Observe oscilloscope waveform
• Verify duty cycle changes

3. System Response Test

• Adjust temperature threshold
• Observe fan speed changes

Precautions

• ADC sampling time must be long enough to ensure accurate temperature readings
• PWM frequency should be set above 20kHz to avoid motor noise
• Ensure the motor driver circuit power supply is independent
• Software filtering should be added in practical applications

Troubleshooting Common Issues

1. Inaccurate Temperature Display

• Check ADC reference voltage settings
• Increase sampling times to take average values

2. Motor Not Rotating

• Check PWM configuration
• Verify connections of the driver circuit

Practical Suggestions

Start by building the minimum system for verification:

1. Only retain temperature acquisition functionality
2. Verify accuracy of ADC data
3. Gradually add PWM control
4. Finally, add display and button functionalities

The challenges of this project include:

• Stability of ADC sampling
• Precision control of PWM output
• Optimization of temperature control algorithms

Recommended debugging tools:

• STM32CubeMX: Quickly configure peripherals
• Virtual Oscilloscope: Observe PWM waveform
• Serial Debugging Assistant: Print debugging information

Finally, a reminder: The real environment may be more complex than simulations, so it is recommended to add:

• Temperature sensor calibration function
• Fault protection mechanism
• Power-on self-check program