2. Overview What kind of LCD Interfacing the LCD Displaying Text and Numbers Common Issues

3. HD44780 Character Display Driver Takes in a parallel data stream and converts it to a character. What kind of LCD??? Nokia and Motorola cell phones Fax machines and Printers Character or Graphic Hitachi HD44780

4. 8 Bit Data Connection 2 Control Pins 8 Data Pins 4 Power Supply Pins Interfacing the LCD PINS GND 1 Vcc 2 Contrast 3 RS 4 R/W 5 E 6 D0 7 D1 8 D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 ASCII characters (10 pins on chip) Power Supply Control Pins Data Pins

5. RS 0 for control codes 1 for display characters E0 while sending cursor positioning code 1 while delivering character Control Lines RS = Register Select E = Clock Input R/W = Ground (power supply line) PINS GND 1 Vcc 2 Contrast 3 RS 4 R/W 5 E 6 D0 7 D1 8 D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 ASCII characters (10 pins on chip) Power Supply Control Pins Data Pins

6. Example Send the letter V to the display and place it in the top center of a 2x8 character display. PINS GND 1 Vcc 2 Contrast 3 RS 4 R/W 5 E 6 D0 7 D1 8 D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 V Cursor Position Codes #$80 #$81 #$82 #$83 #$84 #$85 #$86 #$87 #$88 #$C0 #$C1 #$C2 #$C3 #$C4 #$C5 #$C6 #$C7 #$C8

7. Step 1Drive RS pin low Step 2Send position code #$83 Step 3Drive RS pin high Step 4Drive E pin high Step 5Load ASCII “V” in to the port ASCII “V” = #$56 = 01010110 Step 6Drive E pin low Tells display to accept byte Example Send the letter V to the display and place it in the top center of a 2x8 character display. PINS GND 1 Vcc 2 Contrast 3 RS 4 R/W 5 E 6 D0 7 D1 8 D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 V Control Pins Data Pins

8. 4 Bit Data Connection 2 Control Pins 4 Data Pins 4 Power Supply Pins Interfacing the LCD PINS GND 1 Vcc 2 Contrast 3 RS 4 R/W 5 E 6 D0 7 D1 8 D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 ASCII characters (6 pins on chip) Power Supply Control Pins Data Pins

9. Step 1Drive RS pin low Step 2Send position code #$83 Step 3Drive RS pin high Step 4Drive E pin high Step 5Load high nibble in to the port ASCII “V” = #$5 = 0101 Step 6Drive E pin low Tells display to accept byte Step 7Drive E pin high Step 7Load low nibble in to the port ASCII “V” = #$6 = 0110 Step 6Drive E pin low Tells display to accept byte Example PINS GND 1 Vcc 2 Contrast 3 RS 4 R/W 5 E 6 D0 7 D1 8 D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 V Control Pins Data Pins

10. Shift Registers Save I/O pins on micro processor Requires more effort to stream out data

11. How do you display numbers??? What is the ASCII code for Decimal 75?

12. How do you display numbers??? What is the ASCII code for Decimal 75? The Decimal value must be broken down in to single digits that represent the 100’s, 10’s and 1’s.

13. How do you display numbers??? What is the ASCII code for Decimal 75? The Decimal value must be broken down in to single digits that represent the 100’s, 10’s and 1’s. B inary C oded D ecimal conversion