PCF8574 LCD1602 LCD 1602 Blue/Yellow Green Screen 16X2 Display With Backlight 1602A 5v For Arduino Diy Kit 16x2 LCD modules: long life span, low power consumption, good quality, competitive price. White character with blue backlight 1602 the standard 16 feet interface, among them: 1 foot: for to power VSS 2 feet: VDD take 5 V is power 3 feet: V0 for LCD contrast the adjustment, and then when the power is the weakest contrast, grounding the power supply highest contrast, high contrast can produce the "ghost", when used, can pass a 10 K adjust potentiometer contrast 4 feet: RS for registers choice, high electric usually choose data registers, low electric usually choose instruction register. 5 feet: R/W signal lines for reading and writing, high electric usually are read operation, low electricity at ordinary times for write operation. When the RS and RW together for low electricity can be written instructions at ordinary times, or displays address, when RS for low level for high electricity can usually RW read busy signals, when RS for high level for the low electricity can usually RW write data. 6 feet: E end to make can end, when E is driven by high level jump into low electricity at ordinary times, LCD module executive order. 7 to 14 feet: D0 ~ D7 for eight two-way data cables. 15 feet: backlighting power positive 16 feet: backlighting power negative 1602 LCD module of the internal character happen memory (CGROM) has already been stored 160 different dot matrix characters graphics, as is shown in table 1, these characters have: Arabic numerals, English letters of the case, the commonly used symbols, such as Japanese and under A false name, every character has A fixed code, such as capital letter English the letter "A" code is 01000001 B (41 H), shows the address of the 41 modules H dot matrix characters graphic display out, and we can see the letter "A". The following is the second line LCD module in the position of the first character that the letter "A" program: ORG 0000 H RS EQU P3.7; Determining the specific hardware connection RW EQU P3.6; Determining the specific hardware connection E EQU P3.