Design of ultra-low power LCD display circuit module

　　LCD display module: LCD liquid crystal display is an extremely low power display device with small operating current, light weight, low power consumption, long life, clear and beautiful writing. It is widely used in portable instruments and higher-end instruments for low-power applications. Pin 1: VSS is the ground power supply; Pin 2: VDD is connected to the 5V positive power supply; Pin 3: VL is the contrast adjustment terminal of the LCD display. The contrast is weakest when connected to the positive power supply and the highest when connected to the ground. When the contrast is too high, "ghosting" will occur. The contrast can be adjusted through a 10K potentiometer when in use; Pin 4: RS is the register selection. When the high level is selected, the data register is selected, and when the low level is selected, the instruction register is selected; Pin 5: R/W is the read and write signal line. When the high level is high, the read operation is performed, and when the low level is low, the write operation is performed. When RS and R/W are both low levels, the instruction or display address can be written. When RS is low and R/W is high, the busy signal can be read. When RS is high and R/W is low, data can be written; Pin 6: The E terminal is the enable terminal. When the E terminal jumps from a high level to a low level, the LCD module executes the command; Pins 7-14: D0-D7 are 8-bit bidirectional data lines; Pin 15: The positive pole of the backlight; Pin 16: The negative pole of the backlight.

　　Analysis of display circuit principle: The circuit design is shown in the figure. In the figure, DB0~DB7 of LCD1602 is connected to P00~P07 ports of AT89C52 microcontroller to display user power consumption information; P25, P26, P27 respectively control the register selection input terminal RS, read/write control input terminal R/W, and enable signal input terminal E of LCD1602; the contrast of the LCD display is controlled by adjusting the value of R58 resistance.