Usually we are used to connect LCD displays to 5V systems. As LCD controllers usually require 5V power supply there must be some compliant circuitry used when interfacing to 3V systems like ARM LPC2000 microcontrollers and so on.

Here are few examples how this problem could be solved.

Solution number1:

Standard LCD microcontroller can work with lowered power supply voltage to 2.7V. For this negative voltage for regulating contrast is needed. For this special inverting IC is needed or other solution. In this case there is ability to write and read from LCD controller.

Solution number 2:

This solution is simpler. It doesn’t need negative voltage. But in this case you can only write data to LCD controller -no ability to read for instance LCD status and so on.

It is recommended to connect resistors (about 1kOm) in each data line.

Solution number 3:

Use 8 bit Shift register to send data to LCD.

No ability to read.

Solution number 4:

The best choice would be to use low voltage LCD display like WX1602T. This kind of LCD displays have voltage multipliers on board and you don’t have to wary about power supply.

They also have programmable contrast adjusting and programmable temperature compensation as well. caxapa

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