esp-idf-remote-lcd

Control the HD44780 LCD using HTTP/MQTT.
I use this component.
It's great work.
I made this to know if there are any notify on my HEAD LESS linux server.

Software requirements

ESP-IDF V5.0 or later.
ESP-IDF V4.4 release branch reached EOL in July 2024.

Hardware requirements

Character display using HD44780.
Usually called 1602LCD/1604LCD.

Installation

git clone https://github.com/nopnop2002/esp-idf-remote-hd44780
cd esp-idf-remote-hd44780
idf.py menuconfig
idf.py flash

Configuration

WiFi Setting

Set the information of your access point.

You can connect using the mDNS hostname instead of the IP address.

You can use static IP.

Network protocol Setting

Using HTTP

Using MQTT

Device Setting

Set the information of HD44780 device.

The initial value is no backlight control.

Wiring

LCD		ESP32	ESP32S2/S3	ESP32C2/C3/C6
VSS	--	GND	GND	GND
VDD	--	3.3V/5V	3.3V/5V	3.3V/5V	(*2)
VO	--				Variable resistor output
RS	--	GPIO19	GPIO1	GPIO0	(*1)
RW	--	GND	GND	GND
E	--	GPIO18	GPIO2	GPIO1	(*1)
D0	--	N/C	N/C	N/C
D1	--	N/C	N/C	N/C
D2	--	N/C	N/C	N/C
D3	--	N/C	N/C	N/C
D4	--	GPIO5	GPIO3	GPIO2	(*1)
D5	--	GPIO17	GPIO4	GPIO3	(*1)
D6	--	GPIO16	GPIO5	GPIO4	(*1)
D7	--	GPIO4	GPIO6	GPIO5	(*1)
A	--	3.3V/5V	3.3V/5V	3.3V/5V	(*2)
K	--	GND	GND	GND

(*1) You can change any GPIO using menuconfig.

(*2) 5V for 5V modules. 3.3V for 3.3V modules.

API for HTTP

• cursor:off blink:off(default)
  curl -X POST -H "Content-Type: application/json" -d '{"lcd":"on", "cursor":"off", "blink":"off"}' http://esp32-server.local:8080/api/control

• cursor:on blink:off
  curl -X POST -H "Content-Type: application/json" -d '{"lcd":"on", "cursor":"on", "blink":"off"}' http://esp32-server.local:8080/api/control

• cursor:off blink:on
  curl -X POST -H "Content-Type: application/json" -d '{"lcd":"on", "cursor":"off", "blink":"on"}' http://esp32-server.local:8080/api/control

• cursor:on blink:on
  curl -X POST -H "Content-Type: application/json" -d '{"lcd":"on", "cursor":"on", "blink":"on"}' http://esp32-server.local:8080/api/control

• clear lcd
  curl -X POST http://esp32-server.local:8080/api/clear

• set position
  curl -X POST -H "Content-Type: application/json" -d '{"col":0, "line":0}' http://esp32-server.local:8080/api/gotoxy

• put character on lcd
  curl -X POST -H "Content-Type: application/json" -d '{"char":"s"}' http://esp32-server.local:8080/api/putc

• put string on lcd
  curl -X POST -H "Content-Type: application/json" -d '{"str":"abcdefghijklmn"}' http://esp32-server.local:8080/api/puts

• backlight on
  curl -X POST -H "Content-Type: application/json" -d '{"backlight":"on"}' http://esp32-server.local:8080/api/backlight

• backlight off
  curl -X POST -H "Content-Type: application/json" -d '{"backlight":"off"}' http://esp32-server.local:8080/api/backlight

Backlight control

A transistor is required for backlight control.

ESP32 3.3V/5V --------------------- LCD A
                           +------- LCD K
                           |collector
                           |
                     base /
ESP32 BL  -----^^^--------|    SS8050
              100ohm      \
                           |emitter
ESP32 GND -----------------+

You can use Digital transistor.

ESP32 3.3V/5V --------------------- LCD A
                           +------- LCD K
                           |OUT
                           |
                       IN /
ESP32 BL  ----------------|    Digital transistor
                           \
                           |GND
ESP32 GND -----------------+

Demo for HTTP

sudo apt install curl
bash ./demo_http.sh

API for MQTT

• cursor:off
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/cursor" -m "off"

• cursor:on
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/cursor" -m "on"

• blink:off
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/blink" -m "off"

• blink:on
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/blink" -m "on"

• clear lcd
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/clear" -m ""

• set column
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/col" -m "0"

• set line
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/line" -m "0"

• put character on lcd
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/putc" -m "s"

• put string on lcd
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/puts" -m "abcdefghijklmn"

• backlight on
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/backlight" -m "on"

• backlight off
  mosquitto_pub -h broker.emqx.io -p 1883 -t "/api/hd44780/backlight" -m "off"

Demo for MQTT

sudo apt install mosquitto-clients
bash ./demo_mqtt.sh