I am using UART to display the live readings of my DHT11 sensor similar to this blog post https://controllerstech.com/using-dht11-sensor-with-stm32/ and my program seems to stop around the DHT11_Read() or DHT11_Check_Response() functions. It seems to be some problem with reading the pin and getting a response that I'm not sure if the problem is timing or some problem with the physical device. It won't let me post 100% of the code but here is most of the non-auto generated stuff:
#include "stdio.h"
#include "stdlib.h"
TIM_HandleTypeDef htim6;
UART_HandleTypeDef huart1;
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM6_Init(void);
static void MX_USART1_UART_Init(void);
void delay (uint16_t time)
{
/* change your code here for the delay in microseconds */
__HAL_TIM_SET_COUNTER(&htim6, 0);
while ((__HAL_TIM_GET_COUNTER(&htim6))<time);
}
/* USER CODE END 0 */
uint8_t Rh_byte1, Rh_byte2, Temp_byte1, Temp_byte2;
uint16_t SUM, RH, TEMP;
float Temperature = 0;
float Humidity = 0;
uint8_t Presence = 0;
void Set_Pin_Output (GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
GPIO_InitStruct.Pin = GPIO_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOx, &GPIO_InitStruct);
}
void Set_Pin_Input (GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
GPIO_InitStruct.Pin = GPIO_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_PULLUP;
HAL_GPIO_Init(GPIOx, &GPIO_InitStruct);
}
#define DHT11_PORT GPIOA
#define DHT11_PIN GPIO_PIN_1
void DHT11_Start (void)
{
Set_Pin_Output (DHT11_PORT, DHT11_PIN); // set the pin as output
HAL_GPIO_WritePin (DHT11_PORT, DHT11_PIN, 0); // pull the pin low
delay (18000); // wait for 18ms
HAL_GPIO_WritePin (DHT11_PORT, DHT11_PIN, 1); // pull the pin high
delay (20); // wait for 20us
Set_Pin_Input(DHT11_PORT, DHT11_PIN); // set as input
}
uint8_t DHT11_Check_Response (void)
{
uint8_t Response = 0;
delay (40);
if (!(HAL_GPIO_ReadPin (DHT11_PORT, DHT11_PIN)))
{
delay (80);
if ((HAL_GPIO_ReadPin (DHT11_PORT, DHT11_PIN))) Response = 1;
else Response = -1; // 255
}
while ((HAL_GPIO_ReadPin (DHT11_PORT, DHT11_PIN))); // wait for the pin to go low
return Response;
}
uint8_t DHT11_Read (void)
{
uint8_t i,j;
for (j=0;j<8;j++)
{
while (!(HAL_GPIO_ReadPin (DHT11_PORT, DHT11_PIN))); // wait for the pin to go high
delay (40); // wait for 40 us
if (!(HAL_GPIO_ReadPin (DHT11_PORT, DHT11_PIN))) // if the pin is low
{
i&= ~(1<<(7-j)); // write 0
}
else i|= (1<<(7-j)); // if the pin is high, write 1
while ((HAL_GPIO_ReadPin (DHT11_PORT, DHT11_PIN))); // wait for the pin to go low
}
return i;
}
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
MX_GPIO_Init();
MX_TIM6_Init();
MX_USART1_UART_Init();
/* USER CODE BEGIN 2 */
HAL_TIM_Base_Start(&htim6);
while (1)
{
uint8_t d[] = "Temp: \n";
//printf("TEST HELLO");
//HAL_UART_Transmit(&huart1, (uint8_t)Temperature, sizeof(Temperature), 50);
//HAL_UART_Transmit(&huart1, d , sizeof(d), 50);
/* USER CODE END WHILE */
DHT11_Start();
Presence = DHT11_Check_Response();
Rh_byte1 = DHT11_Read ();
Rh_byte2 = DHT11_Read ();
Temp_byte1 = DHT11_Read ();
Temp_byte2 = DHT11_Read ();
SUM = DHT11_Read();
TEMP = Temp_byte1;
RH = Rh_byte1;
Temperature = (float) TEMP;
Humidity = (float) RH;
uint8_t data[] = "Temp: \n";
// HAL_UART_Receive(&huart1, (uint8_t)Temperature, sizeof(Temperature), 50);
HAL_UART_Transmit(&huart1, (uint8_t)Temperature, sizeof(Temperature), 50);
HAL_UART_Transmit(&huart1, data , sizeof(data), 50);
// HAL_UART_Transmit(&huart1, TEMP , sizeof(TEMP), 50);
HAL_Delay(500);
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
