LCD is divided into COM (common terminal) and SEG (segment selection terminal) For example, there are 4 * 32 LCD can be up to 128 segments independently, can be less can not be more. Each COM and SEG combination corresponds to a segment.
1. LCD lighting is required to change the voltage on both sides, for example, if you want to light up the COM1 and SEG1 combination corresponding to the segment, it is necessary to provide variable voltage to both COM1 and SEG1, generally in the form of square wave
2. close the corresponding segment, as long as the relative voltages at the COM and SEG ends of the corresponding segment are kept unchanged, the segment will not be displayed.
3. the principle of lighting is the above-mentioned content.
If you use a microcontroller without LCD driver to drive the LCD, you need a microcontroller IO port can be independently configured as input or output, used in the COM port, while the COM port connected to two resistors, one to the power supply and one to ground. This will be able to simulate the waveform needed to drive the LCD.
The specific content to be displayed can be achieved through dynamic scanning, which is similar to driving a dot matrix LED!
Here is the example to show you how to use PIC MCU to drive segment LCD display
Using PIC16C5X Microcontrollers as LCD Drivers