1. Teachers Name : Suman Sarker Telecommunication Technology Subject Name : Microcontroller & Embedded System Subject Code : 6871 Semester : 7th Department : Electronics Ideal Institute Of Science & Technology (IIST)

2. LECTURE-11 CH-12 CH-12 LCD AND KEY BOARD INTERFACING

3. LCD DISPLAY An LCD display is specifically manufactured for the use with microcontrollers, which means that it cannot be activated by standard IC circuits. It is used to display different messages on a miniature liquid crystal display. The LCD display described here is for its low price and great capabilities most frequently used in practice. It is based on the HD44780 controller (Hitachi) and displays messages in two lines with 16 characters each. Different symbols such as letters of

4. alphabet, Greek letters, punctuation marks, mathematical symbols etc. can be displayed on it. It is also possible to display symbols created by the user. Other useful features include automatic message shift (left and right), cursor appearance, LED backlight etc.

5. LCD Display Pins Along one side of the small printed board of the LCD display there are pins which enable it to be connected to the microcontroller. There are in total 14 pins marked with numbers (16, if there is a backlight available). Their functions are described in table bellow:

6. FunctionPin NumberNameLogic StateDescription Ground1Vss-0V Power supply2Vdd-+5V Contrast3Vee-0 - Vdd Control of operating 4RS 0101 D0 – D7 considered as commands D0 – D7 considered as data 5R/W 0101 Write data (from controller to LCD) Read data (from LCD to controller) 6E 0 1 From 1 to 0 Access to LCD disabled Normal operating Data/commands being transferred to LCD Data / commands 7D00/1Bit 0 LSB 8D10/1Bit 1 9D20/1Bit 2 10D30/1Bit 3 11D40/1Bit 4 12D50/1Bit 5 13D60/1Bit 6 14D70/1Bit 7 MSB

7. An LCD screen is a thin, flat panel used for displaying different contents. It consists of two lines each containing up to 16 characters of 5x8 or 5x11 pixels. The operation of a 5x8 LCD display will be described here as it is more frequently used.

9. Next Lecture REAL WORLD INTERFACING