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conflicting types error


I'm trying to make a smart irrigation using stm32f407 so, i used a Soil Moisture Sensors 

i write my code but when i trying to run the problem is :Description Resource Path Location Type conflicting types for 'Read_Soil_Moisture'; have 'uint16_t(void)' {aka 'short unsigned int(void)'} main.c /Projectrrr/Core/Src line 89 C/C++ Problem

and this is my code:

Screenshot 2024-06-17 181149.png


so how i can solve this problem

Andrew Neil
Evangelist III

Please use this button to properly post source code:



Please post the full text of the message - copy from the 'Console' window, and paste here.

The full message should tell you both what type it was expecting, and what type it actually got - you've only posted the bit saying what it's got.


#include "main.h"

// Function prototypes
void SystemClock_Config(void);
void Error_Handler(void);
static void MX_GPIO_Init(void);
static void MX_ADC1_Init(void);
static void MX_TIM2_Init(void);

ADC_HandleTypeDef hadc1;
TIM_HandleTypeDef htim2;

int main(void) {

    while (1) {
        uint16_t moisture_level = Read_Soil_Moisture();

        if (moisture_level < 2000) { // Example threshold
            Control_Servo(90); // Open valve
        } else {
            Control_Servo(0);  // Close valve

        HAL_Delay(1000); // Delay for 1 second

void SystemClock_Config(void) {
    // System clock configuration code (auto-generated by STM32CubeMX)

static void MX_GPIO_Init(void) {
    // GPIO initialization code (auto-generated by STM32CubeMX)

static void MX_ADC1_Init(void) {
    ADC_ChannelConfTypeDef sConfig = {0};

    hadc1.Instance = ADC1;
    hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
    hadc1.Init.Resolution = ADC_RESOLUTION_12B;
    hadc1.Init.ScanConvMode = DISABLE;
    hadc1.Init.ContinuousConvMode = DISABLE;
    hadc1.Init.DiscontinuousConvMode = DISABLE;
    hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
    hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
    hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
    hadc1.Init.NbrOfConversion = 1;
    hadc1.Init.DMAContinuousRequests = DISABLE;
    hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
    if (HAL_ADC_Init(&hadc1) != HAL_OK) {
    sConfig.Channel = ADC_CHANNEL_0;
    sConfig.Rank = 1;
    sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;
    if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK) {

static void MX_TIM2_Init(void) {
    TIM_OC_InitTypeDef sConfigOC = {0};

    htim2.Instance = TIM2;
    htim2.Init.Prescaler = 83;
    htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
    htim2.Init.Period = 20000 - 1;
    htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
    htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
    if (HAL_TIM_PWM_Init(&htim2) != HAL_OK) {
    sConfigOC.OCMode = TIM_OCMODE_PWM1;
    sConfigOC.Pulse = 1500; // 1.5ms pulse width (90 degrees)
    sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
    sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
    if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_2) != HAL_OK) {
    HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_2);

  uint16_t Read_Soil_Moisture(void) {
    HAL_ADC_PollForConversion(&hadc1, HAL_MAX_DELAY);
    uint16_t value = HAL_ADC_GetValue(&hadc1);
    return value;

void Control_Servo(uint8_t position) {
    // Convert position (0-180) to pulse width (1ms to 2ms)
    uint16_t pulse = (position * 1000 / 180) + 1000;
    __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_2, pulse);

void Error_Handler(void) {
    while (1) {
        // Stay here...

Lacking in contextual detail.

You've probably defined or used it earlier and the compiler used that.

Check .H files and any instance where you might have created a prototype or used it previously.

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Up vote any posts that you find helpful, it shows what's working..

Used it on line 21 and compiler guessed, you need a prototype or definition before first usage.

uint16_t Read_Soil_Moisture(void); // prototype first, and early

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Up vote any posts that you find helpful, it shows what's working..

You didn't show the full message!

In fact, please show the full build output - that will give more info.


EDIT: This is the 'Console' window - copy from here:






As @Tesla DeLorean said, likely you are calling the Read_Soil_Moisture() function before you have declared it, so the compiler will have created a default declaration.

There should be a warning about that.

Probably, the default declaration doesn't match your actual definition - hence you get the error when the compiler reaches your actual definition.

This is a good example of why it's important to handle compiler messages in order - starting  with the first one reported.


Note that this is general C stuff - nothing specific to STM32

Pavel A.
Evangelist III

In line 21  Read_Soil_Moisture() called without previous declaration. Either move this  function up before main(), or add the prototype declaration after line 8.