[DHT11] add start condition repetition in case the first one fails (which seems to be common with this device)

Core/Src/DHT11.c

@@ -31,29 +31,34 @@ static size_t dht11_read_value(struct DHT11_Data *data)
 
 	register uint32_t read_register = 0;
 
-	TIM2->CNT = 0;
 	HAL_TIM_Base_Start(&htim2);
 
-	GPIOD->MODER |= 0x00400000;       // enable output mode on GPIOD 11
+	// try to trigger the output
+	for (int t = 0; t < 10; t++) {
+		TIM2->CNT = 0;
 
-	GPIOD->BSRR = GPIO_PIN_11;        // enable DHT11
+		GPIOD->MODER |= 0x00400000;       // enable output mode on GPIOD 11
-	wait(50000);                      // hold HIGH for 50 ms
-	GPIOD->BSRR = GPIO_PIN_11 << 16;  // start signal
-	wait(30000);                      // hold it for 30 ms
-	GPIOD->BSRR = GPIO_PIN_11;        // pull up, DHT will now take control over the connection
 
-	wait(100);
+		GPIOD->BSRR = GPIO_PIN_11;        // enable DHT11
-	GPIOD->MODER &= 0xFF3FFFFF;       // switch GPIOD 11 to input mode
+		wait(50000);                      // hold HIGH for 50 ms
+		GPIOD->BSRR = GPIO_PIN_11 << 16;  // start signal
+		wait(30000);                      // hold it for 30 ms
+		GPIOD->BSRR = GPIO_PIN_11;        // pull up, DHT will now take control over the connection
 
-	// reading pull down from DHT11
+		wait(100);
-	SKIP_LOW;
+		GPIOD->MODER &= 0xFF3FFFFF;       // switch GPIOD 11 to input mode
 
-	// waiting for 500ms max
+		// reading pull down from DHT11
-	for (size_t i = TIM2->CNT + (500000 << 4); TIM2->CNT <= i; )
+		SKIP_LOW;
-		if (!(GPIOD->IDR & 0x0800))
+
-			goto reading_data;
+		// waiting for response
+		for (size_t i = TIM2->CNT + (200000 << 4); TIM2->CNT <= i; )
+			if (!(GPIOD->IDR & 0x0800))
+				goto reading_data;
+	}
 
 	// if didn't exit through goto, then DHT11 awaiting has timed out
+	HAL_TIM_Base_Stop(&htim2);
 	return 1;
 
 reading_data:

Core/Src/KSZ8081RND.c

@@ -98,6 +98,7 @@ int ReadRegister(uint32_t reg, uint16_t *value)
 
 	ETH->MACMIIAR = tmpreg1;
 
+	TIM2->CNT = 0;
 	HAL_TIM_Base_Start(&htim2);
 
 	while (ETH->MACMIIAR & 1) {
@@ -122,6 +123,7 @@ int WriteRegister(uint32_t reg, uint16_t value)
 	ETH->MACMIIDR = value;
 	ETH->MACMIIAR = tmpreg1;
 
+	TIM2->CNT = 0;
 	HAL_TIM_Base_Start(&htim2);
 
 	while (ETH->MACMIIAR & 1) {