Home-IoT/esphome
1
0
Fork 0
mirror of https://github.com/esphome/esphome.git synced 2024-11-09 16:57:47 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions 4

Improve DHT read timings (#1901)

Browse source 
Make sure that the initial rising edge is properly detected even if
timing is somewhat off.

Set MCU start signal to 1ms for AM2302.
This commit is contained in:
Stefan Agner 2021-06-22 10:07:14 +02:00 committed by GitHub
parent 027e0de48e
commit 3dfff2930a
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 7 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
esphome/components/dht/dht.cpp
View file

@ -94,11 +94,17 @@ bool HOT ICACHE_RAM_ATTR DHT::read_sensor_(float *temperature, float *humidity,
delayMicroseconds(40);
} else if (this->model_ == DHT_MODEL_DHT22_TYPE2) {
delayMicroseconds(2000);
} else if (this->model_ == DHT_MODEL_AM2302) {
delayMicroseconds(1000);
} else {
delayMicroseconds(800);
}
this->pin_->pin_mode(INPUT_PULLUP);
delayMicroseconds(40);
// Host pull up 20-40us then DHT response 80us
// Start waiting for initial rising edge at the center when we
// expect the DHT response (30us+40us)
delayMicroseconds(70);
uint8_t bit = 7;
uint8_t byte = 0;
@ -116,8 +122,6 @@ bool HOT ICACHE_RAM_ATTR DHT::read_sensor_(float *temperature, float *humidity,
break;
}
}
if (error_code != 0)
break;
start_time = micros();
uint32_t end_time = start_time;
@ -132,8 +136,6 @@ bool HOT ICACHE_RAM_ATTR DHT::read_sensor_(float *temperature, float *humidity,
break;
}
}
if (error_code != 0)
break;
if (i < 0)
continue;