How to DHT22 Temp sensor the simple way

SatNOGS Hardware
1

image

  1. Grab a DHT22 sensor or DHT11.
  2. Connect VCC to 3.3, GND to GND and signal to GPIO 4.
  3. Edit /boot/config.txt to have dtoverlay=dht11,gpiopin=4
  4. reboot
  5. I’m using home assistant to record the data, here is the script I use, modify to whatever you like
    #!/bin/bash
set -eux
set -o pipefail
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
KEY=""
HA_URL="" # no trailing slash


TEMP_VALUE=`cat /sys/bus/iio/devices/iio\:device0/in_temp_input | sed 's/...$/.&/'`
HUMIDITY_VALUE=`cat /sys/bus/iio/devices/iio\:device0/in_humidityrelative_input | sed 's/...$/.&/'`

curl -X POST -H "Authorization: Bearer $KEY" \
 -H "Content-Type: application/json" \
 -d "{\"state\": \"$TEMP_VALUE\", \"attributes\": {\"unit_of_measurement\": \"°C\", \"friendly_name\": \"Satnogs Temp\"}}" \
 $HA_URL/api/states/sensor.satnogs_temp

curl -X POST -H "Authorization: Bearer $KEY" \
 -H "Content-Type: application/json" \
 -d "{\"state\": \"$HUMIDITY_VALUE\", \"attributes\": {\"unit_of_measurement\": \"%\", \"friendly_name\": \"Satnogs Humidity\"}}" \
 $HA_URL/api/states/sensor.satnogs_humidity
  6. Add to crontab - eg * * * * * /root/ha_temp.sh >/dev/null 2>&1

Sometimes you’ll get input/output errors reading. Just try again.

7 Likes