Deskheight sensor

Simple arduino-based sensor to determine the height of my standing desk.

Workflow:

1. main.ino: Attempt to connect to wifi network (blink WIFI LED while connecting, WIFI LED on when connected).
2. main.ino: Determine desk height by measuring 3 times in rapid succession and taking the max value (this smooths out sensor readings).
3. main.ino: Send a basic json payload with the deskheight to my home server (blink SUCCESS LED).
4. main.ino: In case of any issues, blink ERROR LED.
5. home server: listen on port and dump incoming json to file using logstash
6. home server: for every incoming request, create according sensor in home-assistant using logstash
7. home server: in home-assistant, use template sensor to determine whether desk is up or down based on sensor value.

Pictures

Bill of Materials

• Wemos D1 (=cheap arduino clone with wifi chip)
• Arduino compatible ultrasonic sensor HC-SR04
• Arduino compatible 9V Power adapter
• Some LEDs (optional) to indicate connectivity to WiFi network and logstash server.

Wiring Diagram

TODO :-)

Code

The code can be found in main.ino.

Requires some a secrets.h file that sits in the same directory that looks like:

#define SECRET_WIFI_SSID "myssid";
#define SECRET_WIFI_PASSWORD "mysecretpassword";
#define SECRET_HTTP_HOST "10.1.1.1"
#define SECRET_HTTP_PORT 1234
#define SECRET_HTTP_USER "secret-user"
#define SECRET_HTTP_PASSWORD "secret-password"