How to interface 8 LCD displays and 24 leds with only two wires

A couple of weeks ago, I just post a review of my MCP23017 breakout board. As the board configuration allows to connect up to 8 of these boards, I decided to do it and see that it really works. My goal is interface 8 LCD displays with two wires: SDA and SCL from an I2C bus. With direct IO`s of a microcontroller, you need at least 48 lines to control all the displays. With this option (and a little of software, of course), you can do this with only two lines.
interface 8 LCD displays

  • The hardware

The first thing to do is mount the 8 boards. Schematics of the board is available here. Nothing new here, the only thing to consider at this time is to set the address of each board. This is done with the jumpers JP1 – JP3. For this components, I use a 0805 footprint in the PCB, so it’s esay to mount the 0 ohm resistors in the adequate position:
Also, I populated a 4-way polarized connector in order to prevent errors in the connection of the boards, avoid short-circuits between boards. The LCD used is the Winstar WH1602B-NYA-ET#, a standard 2×16 LCD, whit the only disadvantage that this model hasn’t backlight. In the manufacturer web, there’re some examples of code and schematics, including both 4 and 8 bits parallel mode.

  • Boards connection

The most tedious task is to find and mount the 8 LCD’s. How or where I can mount it? Well, after thinking the form of do this, I used two backplane guides to mount all the displays. I use 2,5mm screws to fix it. The result is a bit unstable, but the global mount can handle easy:
For more detail: How to interface 8 LCD displays and 24 leds with only two wires

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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