This is small and fast Arduino library for LCD HD44780 and its clones (S6A0069, KS0066U, NT3881D, LC7985, ST7066, SPLC780, WH160xB, AIP31066, GDM200xD). The display operates in 4-bit mode over I²C bus with 8-bit I/O expander PCF8574/PCF8574A.
The 99.9% of all PCF8574(A) I²C backpacks available on the market are connected like this:
| PCF8574 ports | LCD pins |
|---|---|
| P0 | 4/RS |
| P1 | 5/RW |
| P2 | 6/En |
| P3 | 16/BACKLIGHT LED- (turn-on level HIGH/POSITIVE) |
| P4 | 11/DB4 |
| P5 | 12/DB5 |
| P6 | 13/DB6 |
| P7 | 14/DB7 |
The initialization string for this connection:
// A2=HIGH, A1=HIGH, A0=HIGH P0 P1 P2 P3 P4 P5 P6 P7 backlight turn-on level
LiquidCrystal_I2C lcd(PCF8574_ADDR_A21_A11_A01, 4, 5, 6, 16, 11, 12, 13, 14, POSITIVE);But what if your I²C backpack is different? For example, LCD pin 4/RS is connected to port P6 and LCD's pin 13/DB6 is connected to port P0:
| PCF8574 ports | LCD pins |
|---|---|
| P0 | 13/DB6 |
| P1 | 5/RW |
| P2 | 6/En |
| P3 | 16/BACKLIGHT LED- (turn-on level HIGH/POSITIVE) |
| P4 | 11/DB4 |
| P5 | 12/DB5 |
| P6 | 4/RS |
| P7 | 14/DB7 |
The initialization string in this case:
// A2=HIGH, A1=HIGH, A0=HIGH P0 P1 P2 P3 P4 P5 P6 P7 backlight turn-on level
LiquidCrystal_I2C lcd(PCF8574_ADDR_A21_A11_A01, 13, 5, 6, 16, 11, 12, 4, 14, POSITIVE);Supports:
- Arduino AVR
- Arduino ESP8266
- Arduino ESP32
- Arduino STM32
- Arduino SAMD21