Hi!
I use platformio to develop an app using esp8266 (esp-12E).
I try to use your library so i start with ESP8266I2CLCD.ino as example for testing.
When i compile give me an error.

Verbose mode can be enabled via `-v, --verbose` option
PLATFORM: Espressif 8266 > Espressif ESP8266 ESP-12E
SYSTEM: ESP8266 80MHz 80KB RAM (4MB Flash)
Converting ESP8266I2CLCD.ino
Library Dependency Finder -> http://bit.ly/configure-pio-ldf
LDF MODES: FINDER(chain) COMPATIBILITY(light)
Collected 37 compatible libraries
Scanning dependencies...
Dependency Graph
|-- <Wire> v1.0
|-- <LiquidCrystal_I2C>
|   |-- <Wire> v1.0
Compiling .pioenvs/esp12e/src/ESP8266I2CLCD.ino.cpp.o
Compiling .pioenvs/esp12e/lib837/Wire/utility/twi.c.o
/home/development/.platformio/lib/Wire/src/utility/twi.c:25:20: fatal error: avr/io.h: No such file or directory
#include <avr/io.h>
^
compilation terminated.
*** [.pioenvs/esp12e/lib837/Wire/utility/twi.c.o] Error 1

Here is my platfotrmio.ini file

[env:esp12e]
platform = espressif8266
board = esp12e
framework = arduino
board_f_cpu = 80000000L
build_flags = -Wl,-Teagle.flash.4m1m.ld
upload_speed = 230400

How can solve this?
Thanks in advance!

Why is the same name used as the LCD i2c library for ordinary Arduino boards use? So that users are confused and can not use both the one für ESO8266 and the other für Real Arduinos? Is it so hard to put behind the library name its own string so that there are no problems with different versions for other platforms? Exampel: LiquidCrystal_I2C_ESP8266.h than LiquidCrystal_I2C.h or much better LiquidCrystal_I2C_ESP8266_agn.h that show it is the esp version from agnunez.

If the I2C LCD1602 uses the ST7066U front end, there is no reason to send three I2C bytes in sequence to send a command or a data information. The EN pin of the ST07066U only act on the up-down edge transition of the signal.
It would therefore be beneficial to change the write4bits function to only call the pulseEnable(value) function when the display uses the ST7066U interface chip.

At the start I must say that I am not a programmer but I am able to understand and analyse the workings of a program. The last formal training I had was a six months course on machine code programming on the 8080 in 1986 :)

I was looking at the the ways various types of displays were driven by on the ESP-01S and I got stuck on the LCD 1602 character display. I was running a very simple NTP clock sketch, but I couldn't get it to compile on the Arduino IDE. I don't have the actual error message with me right now, but the error pointed to line 204 of the file LiquidCrystal_I2C.cpp. On comparing with the LiquidCrystal_I2C.cpp file in the link that you attached on your download page, I found that there was a missing "return".

I updated your file with the "return" on line 204 and the sketch compiled, installed on my ESP-01S and ran the display perfectly.

I am not sure why this issue never showed up in all my Google searches or why it wasn't brought up before, I am just glad I could get the script working. I hope this helps.

Terence