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_LCD display-mbed.pdf
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- 10. Using modular codingto interface the LCD display Our LCD.h header /* Program Example 8.1: LCD.h header file */ #ifndef LCD_H #define LCD_H #include "mbed.h" void toggle_enable(void); //function to toggle/pulse the enable bit void LCD_init(void); //function to initialise the LCD void display_to_LCD(char value); //function to display characters #endif
- 11. Initialising the display waita short period (approximately 20 ms), then set the RS and E lines to zero and then send a number of configuration messages to set up the LCD. We then need to send configuration data to the • Function Mode register • Display Mode register • Clear Display register In order to initialise the display.
- 12. Initialising the display FunctionMode To set the LCD function mode, the RS, R/|W and DB0-7 bits should be set as shown below. Remember in 4-bit mode, data bus values are sent as two nibbles.
- 13. Display Mode The DisplayMode control register must also be set up during initialisation. Here we need to send a command to switch the display on, and to determine the cursor function. The Display Mode register is defined as shown below.
- 14. Clear Display Before datacan be written to the display, the display must be cleared, and the cursor reset to the first character in the first row (or any other location that you wish to write data to). The Clear Display command is shown below.
- 15. Sending display datato the LCD
- 18. The mbed TextLCDlibrary The TextLCD definition also tells the LCD object which pins are used for which functions. The object definition is defined in the following manner: TextLCD lcd(int rs, int e, int d0, int d1, int d2, int d3); TextLCD lcd(p19, p20, p21, p22, p23, p24);
- 19. Using the mbedTextLCD library /*Program Example 8.5: TextLCD library Helo World example */ #include "mbed.h" #include "TextLCD.h" TextLCD lcd(p19, p20, p21, p22, p23, p24); //rs,e,d0,d1,d2,d3 int main() { lcd.printf("Hello World!"); }
- 20. /* Program Example8.6: LCD Counter example */ #include "mbed.h“ #include "TextLCD.h“ TextLCD lcd(p19, p20, p21, p22, p23, p24); // rs, e, d0, d1, d2, d3 int x=0; int main() { lcd.printf("LCD Counter"); while (1) { lcd.locate(5,1); lcd.printf("%i",x); wait(1); x++; } }
- 21. /*Program Example 8.8:Displaying a formatted string on the NHD-C12832 */ #include "mbed.h" // Basic Library required for onchip peripherals #include "C12832.h" C12832 lcd(p5, p7, p6, p8, p11); // Initialize lcd int main(){ int j=0; lcd.cls(); // clear screen while(1){ lcd.locate(10,10); // set location to x=10, y=10 lcd.printf("Counter : %d",j); // print counter value j++; // increment j wait(0.5); // wait 0.5 seconds } }