dht22 wrongly reported negative temperatures

[nettle-m]

Operating environment/Installation (Hass.io/Docker/pip/etc.):

Home Assistant OS 5.9 as KVM virtual ESP (ESP32/ESP8266, Board/Sonoff):

esp32doit-devkit-v1 ESPHome version (latest production, beta, dev branch)

ESPHome version 1.15.3 Affected component:

DHT22 https://esphome.io/components/sensor/dht.html

Description of problem: sensor is working fine when temp is above 0C but after temp drops below zero it starts to output wrong values. for example -3276.80005C but those values are correlated with temperature. I think it is some kind of conversion/overflow bug.

Problem-relevant YAML-configuration entries:

esphome:
  name: puda_mala_teplomer
  platform: ESP32
  board: esp32doit-devkit-v1

wifi:
  ssid: "***"
  password: "***"

  # Optional manual IP
  manual_ip:
    static_ip: 192.168.2.41
    gateway: 192.168.2.254
    subnet: 255.255.255.0

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Garaz Teplomer Fallback Hotspot"
    password: "***"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:
  password: "***"

ota:
  password: "***"

sensor:
  - platform: dht
    pin: GPIO05
    temperature:
      name: "mapa_puda Temperature"
    humidity:
      name: "mala_puda Humidity"
    update_interval: 20s
    model: DHT22

Logs (if applicable):

INFO Reading configuration /config/esphome/puda_mala_teplomer.yaml...
INFO Starting log output from 192.168.2.41 using esphome API
INFO Connecting to 192.168.2.41:6053 (192.168.2.41)
INFO Successfully connected to 192.168.2.41
[17:47:40][I][app:105]: ESPHome version 1.15.3 compiled on Jan  7 2021, 17:09:49
[17:47:40][C][wifi:443]: WiFi:
[17:47:40][C][wifi:303]:   SSID: 

[redacted]
[17:47:40][C][wifi:304]:   IP Address: 192.168.2.41
[17:47:40][C][wifi:306]:   BSSID: 

[redacted]
[17:47:40][C][wifi:307]:   Hostname: 'puda_mala_teplomer'
[17:47:40][C][wifi:311]:   Signal strength: -43 dB ▂▄▆█
[17:47:40][C][wifi:315]:   Channel: 1
[17:47:40][C][wifi:316]:   Subnet: 255.255.255.0
[17:47:40][C][wifi:317]:   Gateway: 192.168.2.254
[17:47:40][C][wifi:318]:   DNS1: 0.0.0.0
[17:47:40][C][wifi:319]:   DNS2: 0.0.0.0
[17:47:40][C][logger:185]: Logger:
[17:47:40][C][logger:186]:   Level: DEBUG
[17:47:40][C][logger:187]:   Log Baud Rate: 115200
[17:47:40][C][logger:188]:   Hardware UART: UART0
[17:47:40][C][dht:017]: DHT:
[17:47:40][C][dht:018]:   Pin: GPIO5 (Mode: INPUT)
[17:47:40][C][dht:024]:   Model: DHT22 (or equivalent)
[17:47:40][C][dht:027]:   Update Interval: 20.0s
[17:47:40][C][dht:029]:   Temperature 'mapa_puda Temperature'
[17:47:40][C][dht:029]:     Unit of Measurement: '°C'
[17:47:40][C][dht:029]:     Accuracy Decimals: 1
[17:47:40][C][dht:029]:     Icon: 'mdi:thermometer'
[17:47:40][C][dht:030]:   Humidity 'mala_puda Humidity'
[17:47:40][C][dht:030]:     Unit of Measurement: '%'
[17:47:40][C][dht:030]:     Accuracy Decimals: 0
[17:47:40][C][dht:030]:     Icon: 'mdi:water-percent'
[17:47:40][C][captive_portal:169]: Captive Portal:
[17:47:40][C][ota:029]: Over-The-Air Updates:
[17:47:40][C][ota:030]:   Address: 192.168.2.41:3232
[17:47:40][C][ota:032]:   Using Password.
[17:47:40][C][api:095]: API Server:
[17:47:40][C][api:096]:   Address: 192.168.2.41:6053
[17:47:46][D][dht:048]: Got Temperature=12.7°C Humidity=94.5%
[17:47:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 12.70000 °C with 1 decimals of accuracy
[17:47:46][D][sensor:092]: 'mala_puda Humidity': Sending state 94.50000 % with 0 decimals of accuracy
[17:48:06][D][dht:048]: Got Temperature=13.8°C Humidity=93.8%
[17:48:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 13.80000 °C with 1 decimals of accuracy
[17:48:06][D][sensor:092]: 'mala_puda Humidity': Sending state 93.80000 % with 0 decimals of accuracy
[17:48:26][D][dht:048]: Got Temperature=14.3°C Humidity=80.3%
[17:48:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 14.30000 °C with 1 decimals of accuracy
[17:48:26][D][sensor:092]: 'mala_puda Humidity': Sending state 80.30000 % with 0 decimals of accuracy
[17:48:46][D][dht:048]: Got Temperature=13.2°C Humidity=56.6%
[17:48:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 13.20000 °C with 1 decimals of accuracy
[17:48:46][D][sensor:092]: 'mala_puda Humidity': Sending state 56.60000 % with 0 decimals of accuracy
[17:49:06][D][dht:048]: Got Temperature=11.6°C Humidity=52.4%
[17:49:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 11.60000 °C with 1 decimals of accuracy
[17:49:06][D][sensor:092]: 'mala_puda Humidity': Sending state 52.40000 % with 0 decimals of accuracy
[17:49:26][D][dht:048]: Got Temperature=10.0°C Humidity=51.3%
[17:49:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 10.00000 °C with 1 decimals of accuracy
[17:49:26][D][sensor:092]: 'mala_puda Humidity': Sending state 51.30000 % with 0 decimals of accuracy
[17:49:46][D][dht:048]: Got Temperature=8.5°C Humidity=52.8%
[17:49:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 8.50000 °C with 1 decimals of accuracy
[17:49:46][D][sensor:092]: 'mala_puda Humidity': Sending state 52.80000 % with 0 decimals of accuracy
[17:50:06][D][dht:048]: Got Temperature=7.2°C Humidity=56.1%
[17:50:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 7.20000 °C with 1 decimals of accuracy
[17:50:06][D][sensor:092]: 'mala_puda Humidity': Sending state 56.10000 % with 0 decimals of accuracy
[17:50:26][D][dht:048]: Got Temperature=6.1°C Humidity=58.0%
[17:50:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 6.10000 °C with 1 decimals of accuracy
[17:50:26][D][sensor:092]: 'mala_puda Humidity': Sending state 58.00000 % with 0 decimals of accuracy
[17:50:46][D][dht:048]: Got Temperature=5.0°C Humidity=59.9%
[17:50:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 5.00000 °C with 1 decimals of accuracy
[17:50:46][D][sensor:092]: 'mala_puda Humidity': Sending state 59.90000 % with 0 decimals of accuracy
[17:51:06][D][dht:048]: Got Temperature=4.2°C Humidity=63.4%
[17:51:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 4.20000 °C with 1 decimals of accuracy
[17:51:06][D][sensor:092]: 'mala_puda Humidity': Sending state 63.40000 % with 0 decimals of accuracy
[17:51:26][D][dht:048]: Got Temperature=3.4°C Humidity=65.3%
[17:51:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 3.40000 °C with 1 decimals of accuracy
[17:51:26][D][sensor:092]: 'mala_puda Humidity': Sending state 65.30000 % with 0 decimals of accuracy
[17:51:46][D][dht:048]: Got Temperature=2.7°C Humidity=67.1%
[17:51:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 2.70000 °C with 1 decimals of accuracy
[17:51:46][D][sensor:092]: 'mala_puda Humidity': Sending state 67.10000 % with 0 decimals of accuracy
[17:52:06][D][dht:048]: Got Temperature=2.2°C Humidity=69.1%
[17:52:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 2.20000 °C with 1 decimals of accuracy
[17:52:06][D][sensor:092]: 'mala_puda Humidity': Sending state 69.10000 % with 0 decimals of accuracy
[17:52:26][D][dht:048]: Got Temperature=1.7°C Humidity=70.9%
[17:52:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 1.70000 °C with 1 decimals of accuracy
[17:52:26][D][sensor:092]: 'mala_puda Humidity': Sending state 70.90000 % with 0 decimals of accuracy
[17:52:46][D][dht:048]: Got Temperature=1.3°C Humidity=72.5%
[17:52:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 1.30000 °C with 1 decimals of accuracy
[17:52:46][D][sensor:092]: 'mala_puda Humidity': Sending state 72.50000 % with 0 decimals of accuracy
[17:53:06][D][dht:048]: Got Temperature=1.0°C Humidity=73.9%
[17:53:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 1.00000 °C with 1 decimals of accuracy
[17:53:06][D][sensor:092]: 'mala_puda Humidity': Sending state 73.90000 % with 0 decimals of accuracy
[17:53:26][D][dht:048]: Got Temperature=0.7°C Humidity=75.1%
[17:53:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 0.70000 °C with 1 decimals of accuracy
[17:53:26][D][sensor:092]: 'mala_puda Humidity': Sending state 75.10000 % with 0 decimals of accuracy
[17:53:46][D][dht:048]: Got Temperature=0.4°C Humidity=76.0%
[17:53:46][D][sensor:092]: 'mapa_puda Temperature': Sending state 0.40000 °C with 1 decimals of accuracy
[17:53:46][D][sensor:092]: 'mala_puda Humidity': Sending state 76.00000 % with 0 decimals of accuracy
[17:54:06][D][dht:048]: Got Temperature=0.2°C Humidity=76.8%
[17:54:06][D][sensor:092]: 'mapa_puda Temperature': Sending state 0.20000 °C with 1 decimals of accuracy
[17:54:06][D][sensor:092]: 'mala_puda Humidity': Sending state 76.80000 % with 0 decimals of accuracy
[17:54:26][D][dht:048]: Got Temperature=0.0°C Humidity=77.7%
[17:54:26][D][sensor:092]: 'mapa_puda Temperature': Sending state 0.00000 °C with 1 decimals of accuracy
[17:54:26][D][sensor:092]: 'mala_puda Humidity': Sending state 77.70000 % with 0 decimals of accuracy
[17:54:46][D][dht:048]: Got Temperature=-3276.8°C Humidity=78.5%
[17:54:46][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.80005 °C with 1 decimals of accuracy
[17:54:46][D][sensor:092]: 'mala_puda Humidity': Sending state 78.50000 % with 0 decimals of accuracy
[17:55:06][D][dht:048]: Got Temperature=-3276.7°C Humidity=79.0%
[17:55:06][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.69995 °C with 1 decimals of accuracy
[17:55:06][D][sensor:092]: 'mala_puda Humidity': Sending state 79.00000 % with 0 decimals of accuracy
[17:55:26][D][dht:048]: Got Temperature=-3276.5°C Humidity=79.5%
[17:55:26][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.50000 °C with 1 decimals of accuracy
[17:55:26][D][sensor:092]: 'mala_puda Humidity': Sending state 79.50000 % with 0 decimals of accuracy
[17:55:46][D][dht:048]: Got Temperature=-3276.4°C Humidity=80.0%
[17:55:46][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.40015 °C with 1 decimals of accuracy
[17:55:46][D][sensor:092]: 'mala_puda Humidity': Sending state 80.00000 % with 0 decimals of accuracy
[17:56:06][D][dht:048]: Got Temperature=-3276.3°C Humidity=80.4%
[17:56:06][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.30005 °C with 1 decimals of accuracy
[17:56:06][D][sensor:092]: 'mala_puda Humidity': Sending state 80.40000 % with 0 decimals of accuracy
[17:56:26][D][dht:048]: Got Temperature=-3276.2°C Humidity=80.7%
[17:56:26][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.19995 °C with 1 decimals of accuracy
[17:56:26][D][sensor:092]: 'mala_puda Humidity': Sending state 80.70000 % with 0 decimals of accuracy
[17:56:46][D][dht:048]: Got Temperature=-3276.2°C Humidity=81.2%
[17:56:46][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.19995 °C with 1 decimals of accuracy
[17:56:46][D][sensor:092]: 'mala_puda Humidity': Sending state 81.20000 % with 0 decimals of accuracy
[17:57:06][D][dht:048]: Got Temperature=-3276.1°C Humidity=82.0%
[17:57:06][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.10010 °C with 1 decimals of accuracy
[17:57:06][D][sensor:092]: 'mala_puda Humidity': Sending state 82.00000 % with 0 decimals of accuracy
[17:57:26][D][dht:048]: Got Temperature=-3276.0°C Humidity=82.3%
[17:57:26][D][sensor:092]: 'mapa_puda Temperature': Sending state -3276.00000 °C with 1 decimals of accuracy
[17:57:26][D][sensor:092]: 'mala_puda Humidity': Sending state 82.30000 % with 0 decimals of accuracy

Additional information and things you've tried: I tried to change sensor type to all possible values: AUTO_DETECT, DHT11, DHT22, DHT22_TYPE2, AM2302, RHT03, SI7021

none of them solved the issue

[nettle-m]

as workaround i used this filter:

filters:
        - lambda: !lambda if ( x < -1000.0 ) { return (-1) * x - 3277.0; } else { return x; }

now temperatures in home-assistant show as they should

[probot-esphome[bot]]

dht source dht issues dht recent changes _{^{(message by IssueLinks)}}

[nettle-m]

just update: problem is still present in ESPHome version 1.16.0

[SenexCrenshaw]

Can you try the latest dev branch?

[nettle-m]

Hello, i dont want to mess with my current Home Assistant i will try to setup new instance with ESPHome dev version, but it will take some time

[nettle-m]

i was unsuccessful in dev esphome deployment. Could you guide me how can i upgrade ESPHome HO addon to dev version?

[SenexCrenshaw]

Have you tried adding a 4.7k pullup like in the docs? https://esphome.io/components/sensor/dht.html

[nettle-m]

yes, i have dht22 connected with pull up resistor from the start

[agners]

This very much matches what is described in this comment: https://github.com/esphome/esphome/pull/926#issuecomment-602110509

That got fixed with the DHT22 Type 2 introduction. Are you sure DHT22_TYPE2 doesn't fix your problem?

[gb53smith]

You may want try this custom sensor from my post. It uses a newer and perhaps better DHT library. Your issue appears to be the same as found in a much older DHT library. Esphome folks may have missed a bug fix and not copied it into their DHT component.

Looking at the dht.cpp I see:

 if (this->model_ != DHT_MODEL_DHT22_TYPE2 && (raw_temperature & 0x8000) != 0)
      raw_temperature = ~(raw_temperature & 0x7FFF);

That should convert the sign-magnitude binary value to 2's complement required to represent a negative temperature for the conversion to int16_t later in code. This will give you a large negative number if model = DHT22_TYPE2 is used.

[gb53smith]

@nettle-m You may want to test your DHT using the new external component integration

  - source: github://gb53smith/esphome@devsweep
    components: [dht]

It is based on github://esphome/esphome@dev with the added test of sweeping the start delay between 800 and 20000 us. (To prove a theory that the start delay was never the true cause bad readings.) The model: must be set to AM2302 for the test to be activated.

When github://esphome/esphome@dev get released use model: DHT22 Never use model: DHT22_TYPE2 unless your DHT datasheet indicates 2's complement representation of negative temperatures

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.