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

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ІО-23 Шмуляр Олег 2025-05-10 13:57:50 +03:00
parent a3925be518
commit df649b3ba5
1 changed files with 20 additions and 15 deletions
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35
Core/Src/DHT11.c
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@ -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
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
GPIOD->MODER |= 0x00400000; // enable output mode on GPIOD 11
wait(100);
GPIOD->MODER &= 0xFF3FFFFF; // switch GPIOD 11 to input mode
GPIOD->BSRR = GPIO_PIN_11; // enable DHT11
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
SKIP_LOW;
wait(100);
GPIOD->MODER &= 0xFF3FFFFF; // switch GPIOD 11 to input mode
// waiting for 500ms max
for (size_t i = TIM2->CNT + (500000 << 4); TIM2->CNT <= i; )
if (!(GPIOD->IDR & 0x0800))
goto reading_data;
// reading pull down from DHT11
SKIP_LOW;
// 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: