selfhost-utils/esp32-lcd/README.md

# ESP32-LCD

A status LCD for your homelab.

![ESP32-LCD prototype](../images/esp32-lcd.jpg)

## BOM

- Any HD44780-based character LCD display, up to 20x4 characters. The most common are 16x2 characters (16 characters per row, 2 rows).
- An ESP-32 board
- A potentiometer, usually a 10 or 100k one, for controlling contrast (a couple of resistances arranged as a voltage divider may also be fine)

## Assembly

Connect the LCD to the board:

LCD Pin		ESP32 Pin
____________________________________
PIN01-VSS	GND
PIN02-VDD	5V
PIN03 V0	10K Pot (Middle pin)
PIN04 RS	GPIO19
PIN05 RW	GND
PIN06  E	GPIO23
PIN07 D0	NOT USED
PIN08 D1	NOT USED
PIN09 D2	NOT USED
PIN10 D3	NOT USED
PIN11 D4	GPIO18
PIN12 D5	GPIO17
PIN13 D6	GPIO16
PIN14 D7	GPIO15
PIN15 A		5V
PIN16 K		GND

Connect the potentiometer lateral pins to VCC and GND. Use the potentiometer to set the screen contrast.

Open config.h file and set display size and your wifi access data.

Flash the code to the ESP32. If you use the Arduino ide to do it, just open the esp32-lcd.ino file with the Arduino ide and follow [this instructions](https://randomnerdtutorials.com/getting-started-with-esp32/)

Restart the ESP32. The display shows "Conn to wifi..." with the WIFI name in the second line (if using a two or more lines display) and then will show the IP address.

## Use

- Turn on the circuit, wait for connection and note down the IP address shown on the screen.
- Make a GET request to the same IP address with a parameter "message" containing some text

> Example: to make the request using CURL from command line, try something along this lines (replace the IP addr with the one shown in the display):
> curl -G http://192.168.1.78 --data-urlencode "message=Something interesting happened!"

## Troubleshooting

The ESP32 logs are written in the serial monitor at 115200 baud. Just open the Arduino ide Serial Monitor from Tools menu and look at the logs.