USING A 16x2 LCD DISPLAY WITH THE IoT PROTO SHIELD PLUS

USING A 16x2 LCD DISPLAY WITH THE IoT PROTO SHIELD PLUS

The IoT Proto Shield Plus is ready to work with 16 pins LCD 1602 displays of widespread use.
To work with an LCD 1602 display, just plug the module into the LCD16x2 header according to Figure below.
Use RV1 to adjust the LCD contrast.
The LCD 1602 is driven by I²C by means of the onboard PCF8574 (I²C I/O expander) and it does not require any additional wiring.
Signal connections are the same used in the LCD I²C adapter of widespread use.
Since ESP32, ESP8266 and NANO33 boards works at 3.3V, to have a sufficient contrast on the display, ICL7660 is used to ensure a sufficient voltage to the V0 pin of the LCD 1602 module.
Depending on component availability, the I/O expander 8574 could be the PCF8574 or the PCF8574A.
Both versions perform the same, the only difference is the base address of the I²C communication.
Since A0, A1 and A2 of the PCF8574 connect to ground by default (by means of JP17, JP16 and JP15), the default address is set to 0x20 (PCF8574) or 0x38 (PCF8574A).
Use the sample sketches described below to find out which version is your one.

LCD 16x2 header of the IoT Proto Shield Plus

Schematic of the IoT Proto Shield Plus LCD 16x2 section
 

An LCD 1602 display module plugged into the 16 pins header of the IoT Proto Shield Plus

DEFAULT CONNECTIONS

Refer to the blog article "I2C Bus on the IoT Proto Shield Plus" to see default routing of I²C signals on the IoT Proto Shield Plus.

SAMPLE SKETCHES

Download the sample sketches by clicking here.

Location: IoTPSP_Sample_Sketches/IoTPSP_LCD16x2

These sketches make use of the LiquidCrystal_I2C library, you will find the library in the IoTPSP_Sample_Sketches/IoTPSP_LCD16x2 path.

Use the IoTPSP_LCD16x2_NANO sketch to test the LCD1602 with ARDUINO NANO boards.
Use the IoTPSP_LCD16x2_ESP32 sketch to test the LCD1602 with ESP32 boards.
Use the IoTPSP_LCD16x2_ESP8266 sketch to test the LCD1602 with ESP8266 boards.

Changing the I2C address of the PCF8574

It is not very usual, but in case that you want or need to change the address of the 8574 chip, you have to OPEN or CLOSE JP17, JP16 and JP15 according to your needs and the PCF8574 datasheet.
To OPEN JP17, JP16 or JP15 cut them in the middle.
To CLOSE them solder a little drop of tin.

Using the PCF8574 with different I2C GPIO pins

Refer to the blog article "I2C Bus on the IoT Proto Shield Plus" to see how to use I²C with different GPIO pins on the IoT Proto Shield Plus.

Related products

IoT Proto Shield Plus

IoT Proto Shield Plus ESP32 STARTER KIT

IoT Proto Shield Plus OLED KIT