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Alphanumeric LCD
Alphanumeric LCDs are popular for projecting data and information quickly and efficiently. To use
them, we do not need any additional hardware feature in a micro. Digital I/Os are what we need to
use these displays.
Usually to use these LCDs we need 5V power supply. 3.3V versions of these LCD are rare on the other
hand. It is, however, possible to power up 5V version LCDs with 5V supply while using 3.3V logic for
communication. In TTL logic, something above 2.8V is just above the minimum allowed logic high
voltage. When VDD is less than 3V, it, then, becomes necessary to use logic level conversion circuitry.
Here in my demo I used a 3.3V version LCD to keep things simple and tidy. Shown below are LCDs for
different voltage levels. Both LCDs look same but if you check the backside of both LCDs you’ll notice
a difference. In the 3.3V version LCD, there are some additional components present, notably an 8 pin
SMD IC. This is a ICL7660 negative voltage generator IC.
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