1602 LCD Command Introduction

Similar to the usage of MCU registers, when using 1602 LCD, we must first perform initial function configuration. There are several instructions for 1602 LCD that need to be understood.

1)
Write instruction 0x38 to set the display mode, set 16x2 display, 5x7 dot matrix, 8-bit data interface. This instruction is fixed for our LCD, and 0x38 must be written. If you look carefully, you will find that our LCD actually has an internal dot matrix of 5x8. Some 1602 LCDs are also compatible with serial communication, which can be done with 2 IO ports, but the speed is slow. Our LCD is fixed to 0x38 mode.

2) Display on/off and cursor setting instructions
There are 2 instructions here. The first instruction has 8 bits in a byte, of which the upper 5 bits are fixed to 0b00001, and the lower 3 bits are represented by DCB from high to low. D=1 means display on, D=0 means display off; C=1 means display cursor, C=0 means no display cursor; B=1 means cursor blinking, B=0 means cursor not blinking.

The second instruction has 6 upper bits fixed to 0b000001, and the lower 2 bits are represented by NS from high to low. N=1 means that after reading or writing a character, the pointer automatically increases by 1 and the cursor automatically increases by 1. N=0 means that after reading or writing a character, the pointer automatically decreases by 1 and the cursor automatically decreases by 1. S=1 means that after writing a character, the entire screen display moves left (N=1) or right (N=0) to achieve the effect of the cursor not moving but the screen moving, just like the effect of our calculator input, and S=0 means that after writing a character, the entire screen display does not move.

3) The clear screen instruction
is fixed. Writing 0x01 means clearing the screen, which includes clearing the data pointer and all displays. Writing 0x02 means only clearing the data pointer, but not the display.

4) RAM address setting instruction
The highest bit of the instruction code is 1, and the lower 7 bits are the RAM address. The relationship between the RAM address and the characters on the LCD is shown in Figure 12-2 above. Usually, we have to set the address before reading and writing data, and then perform data reading and writing operations.