How to find the right LCD Dot Matrix Modules AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in LCD Dot Matrix Modules
- Controller IC
- Buy only listings that name the controller (for example ST7920, KS0108/NT7108, ST7565/ST7567, PCD8544). Confirm that your library supports it; u8g2 covers most of them. The controller decides the command set, the pinout and whether working driver code exists. The resolution alone tells you none of this.
- Logic voltage
- Match the module's logic level to your microcontroller (5V or 3.3V). Otherwise add level shifting. Many 128x64 parallel modules are 5V parts. They behave unreliably or fail to show anything when driven from 3.3V boards.
- Interface and pin count
- Prefer serial (SPI or I2C) when pins are scarce. Parallel 8-bit buses use about 13 or more I/O lines. KS0108-style modules are parallel-only. ST7920 and ST7565 modules can run serially and save most of your pins.
- Contrast voltage
- Check whether a negative or bias voltage is generated on board. Also check whether a contrast potentiometer is fitted or must be added. Some KS0108 modules need an external negative supply or pot. Without it the panel looks blank even when it is wired correctly.
- Display mode and backlight
- Choose positive (dark pixels on a yellow-green or white background) or transflective panels for bright or outdoor use. Choose negative (blue or black background) only for indoor use with the backlight on. Negative-mode panels are hard to read in sunlight and are unreadable with the backlight off.
- Physical fit
- Match the outline dimensions, viewing area and pin header position to your enclosure or replacement slot. Modules sold under the same name, such as 12864, differ in size and in pin order between makers.
Brands that matter
- Newhaven Display: Industrial graphic LCD modules with full datasheets and long-term availability.
- Crystalfontz: Well-documented graphic LCD modules, with sample code for many controllers.
- Adafruit: Hobbyist breakouts such as ST7565 128x64 and Nokia 5110-style displays, with maintained libraries.
- SparkFun: Graphic LCD breakouts with hookup guides aimed at microcontroller users.
- Waveshare: Broad range of display modules, with wiki documentation and demo code.
- DFRobot: Maker-oriented LCD modules, often supplied with a pre-wired serial interface.
What to avoid
- Listings that give a resolution such as 12864 but do not name the controller IC or provide a pinout.
- Driving a 5V-logic module directly from a 3.3V board without checking that it accepts 3.3V levels.
- Negative-mode (blue background) panels for devices read outdoors or without a backlight.
- Assuming an OLED module is a drop-in replacement for an LCD module: the controllers and libraries differ.
Questions
How do I tell whether a 128x64 module is ST7920 or KS0108?
Check the pin labels. ST7920 modules usually have a PSB pin for selecting serial or parallel mode. KS0108 modules have two chip-select pins (CS1 and CS2) because each half of the screen has its own controller.
Should I pick a dot matrix module or a character module?
A character module only shows fixed text cells. A dot matrix (graphic) module addresses every pixel, so it can draw icons, graphs and custom fonts. It needs more memory and more driver code.