Story
What is Alphanumerical LCD
Alphanumerical LCD’s is pretty old but still good to use devices. They can display basic alphabetical characters, numbers but also you can upload your own characters in their memory and use them for special stuff.
You can get them from variety of sources (for example on Adafruit) in different number of characters, with different number of lines and variety of colors and with or without back-light.
Almost all of them use communication based on old HD44780 chip and consists 0.1″ row so is easily to use and easy to solder. In real world you need only LCD, Raspberry, one potentiometer and couple of wires.
Why I should use such obsolete technology ?
Well, this technology is far from obsolete. And how you can use it ? Here is just few samples :
Also don’t forget that you don’t need use green/black display (which looks cheap) but you can use inversion displays with white, blue or red text. They looks really good on any project.
Connection
LCD can be connected over 8 data wires or over 4 data wires. Current version of library and this project covers only 4 data wires because speed penalty is not big and you can safe 4 additional GPIO port on Raspi for other hardware. Besides of of 4 data wire you need two additional wires for driving communication. Also 5V, GND and potentiometer to set contrast is needed to be connected as is on following screen.
Warning – Raspi with Win 10 IoT Core will allow you use only selected ports for general IO. Special ports like SPI or I2C is not allowed to be used and you will get exception if you do so.
Warning 2 – After connection you can see two lines filled with blocks. This is normal situation and it is correct. Display will clear after proper initialization from code. Don’t worry 🙂
LCD size
You can get various of LCDs. Most common size is 16×2 and 20×4. Library supports all modes uses one HD44780 chip. Others sizes are 8×1, 16×1, 16×4 and 20×2 but you can also find some custom version with different sizes.
Schematic
Schematic uses 4 wire data connection, 10k potentiometer for contrast and direct 5V for backlight led on display. Please check your LCD datasheet, there is possibility that your LCD will need resistor in connection just as normal led.
