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Improve DHT read timings (#1901)
Make sure that the initial rising edge is properly detected even if timing is somewhat off. Set MCU start signal to 1ms for AM2302.
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027e0de48e
commit
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1 changed files with 7 additions and 5 deletions
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@ -94,11 +94,17 @@ bool HOT ICACHE_RAM_ATTR DHT::read_sensor_(float *temperature, float *humidity,
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delayMicroseconds(40);
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} else if (this->model_ == DHT_MODEL_DHT22_TYPE2) {
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delayMicroseconds(2000);
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} else if (this->model_ == DHT_MODEL_AM2302) {
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delayMicroseconds(1000);
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} else {
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delayMicroseconds(800);
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}
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this->pin_->pin_mode(INPUT_PULLUP);
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delayMicroseconds(40);
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// Host pull up 20-40us then DHT response 80us
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// Start waiting for initial rising edge at the center when we
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// expect the DHT response (30us+40us)
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delayMicroseconds(70);
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uint8_t bit = 7;
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uint8_t byte = 0;
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@ -116,8 +122,6 @@ bool HOT ICACHE_RAM_ATTR DHT::read_sensor_(float *temperature, float *humidity,
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break;
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}
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}
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if (error_code != 0)
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break;
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start_time = micros();
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uint32_t end_time = start_time;
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@ -132,8 +136,6 @@ bool HOT ICACHE_RAM_ATTR DHT::read_sensor_(float *temperature, float *humidity,
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break;
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}
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}
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if (error_code != 0)
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break;
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if (i < 0)
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continue;
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