Wifi temperature sensor with ESP-01 and DHT22

Setup

• On the ESP-01, use a jumper wire to connect GPIO0 and GND to enable flash mode
• Create a custom build of NodeMCU 1.5.4.1-final, with the following modules: DHT, file, GPIO, HTTP, net, node, timer, UART, WiFi
• Install nodemcu v1.0 driver
• Flash the ESP-01 wifi module position 0x00000 with custom built firmware (float version) using esptool i.e. esptool.py --port /dev/tty.wchusbserial1410 write_flash 0x00000 ./nodemcu-1.5.4.1-final-9-modules-2020-04-03-04-23-13-float.bin
• Use stty -f /dev/cu.wchusbserial1410 115200 & to set the serial Baud
• Download ESP8266 / NodeMCU / MicroPhython IDE ESPlorer
• Open ESPlorer, switch to NodeMCU+MicroPython tab
• Open and change settings in config.lua
• Rename pull.lua or push.lua to init.lua
• Upload config.lua and init.lua to the wifi module by clicking on Save to ESP

Parts & Tools

Components

• ESP-01
• DHT22

Development

• USB to ESP8266 Serial Wireless Wi-Fi Module
  • Driver (ch340)
• Custom development board Badly soldered example above...

Wiring

References

• Adafruit ESP8266 Temperature / Humidity Webserver Tutorial
• Capturing Sensor Data: DHT22
• Wiring the ESP8266 As Stand Alone
• ESP8266 Wikipedia | ESP8266 Community - Module Family

Documentation

• NodeMCU Documentation
• ESP8266 Arduino Core Documentation

Datasheet

• ESP-01 WiFi Module
• DHT22

Further reading

• Hack to enable deep sleep mode on the ESP-01
• My odyssey across the trails of technology