This Blue 20x4 LCD module supports bidirectional I2C, is reasonably priced and works well with NodeMCU. The I2C support is provided by the attached PCF8574T backpack module. The supply voltage is 5V and the SDA/SLC lines are
The PCF8574 data sheet states in the DC characteristics section that the minimum HIGH level input voltage for SCL and SDA is 0.7 times the supply voltage. This equates to:
As the NodeMCU output is 3.3V a logic level shifter is used to convert the 3.3V to 5V levels.
The LCD is controlled via the following pin assignments:LCD I2C | NodeMCU | GPIO |
SDA | D4 | GPIO2 |
SLC | D5 | GPIO14 |
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