Character LCD module is a type of LCD display, designed to display characters, numerical numbers, sign, etc. 16*1, 16*2, 20*2, 40*2 are most frequently used modules.
Specifications and Pin Assignment
There are two types of 1602 LCD, with backlight one, and without backlight one. Its controller IC is HD44780. The LCD with backlight is thicker than that without backlight. Their dimensional difference are shown in below picture.
Display Content: 16 * 2 characters
Operation Voltage: 4.5 – 5.5V
Working Current: 2.0mA at 5.0V
Recommended Working Voltage: 5.0V
Character Dimension: 2.95 * 4.35 (W * H)mm
| Pin No. | Symbol | Function |
| 1 | Vss | Ground |
| 2 | Vdd | +5V |
| 3 | VL | LCD contrast adjust.When VL is connected to Vdd, LCD contrast is the lowest. When VL is connected to Vss, LCD contrast is the highest. For best visibility, use a 10k potentiometer to get the suitable resistance. |
| 4 | RS | Register select.High level to select data register. Low level to select command register. |
| 5 | R/W | Read / WriteHigh level to read and low level to write. When both RS and R/W are low, command or data address can be written. When RS is low, and R/W is high, busy signal can be read. When RS is high and R/W is low, data is allowed to be written into registers. |
| 6 | E | EnableHigh to low level, LCD execute commands. |
| 7 | DB0 | Data bit 0. Bidirectional data bus. |
| 8 | DB1 | Data bit 1 Bidirectional data bus. |
| 9 | DB2 | Data bit 2 Bidirectional data bus. |
| 10 | DB3 | Data bit 3 Bidirectional data bus. |
| 11 | DB4 | Data bit 4 Bidirectional data bus. |
| 12 | DB5 | Data bit 5 Bidirectional data bus. |
| 13 | DB6 | Data bit 6 Bidirectional data bus. |
| 14 | DB7 | Data bit 7 Bidirectional data bus. |
| + | BL+ | Power Supply for BL+ |
| - | BL- | Power Supply for BL- |
Instruction and Timing
| Instruction | RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 |
| Clear Display | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Cursor At Home | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | - |
| Entry Mode Set | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | I/D | SH |
| Display On/Off Control | 0 | 0 | 0 | 0 | 0 | 0 | 1 | D | C | B |
| Cursor or Display Shift | 0 | 0 | 0 | 0 | 0 | 1 | S/C | R/L | - | - |
| Function Set | 0 | 0 | 0 | 0 | 1 | DL | N | F | - | - |
| Set CGRAM Address | 0 | 0 | 0 | 1 | AC5 | AC4 | AC3 | AC2 | AC1 | AC0 |
| Set DDRAM Address | 0 | 0 | 1 | AC6 | AC5 | AC4 | AC3 | AC2 | AC1 | AC0 |
| Read Busy Flag and Address | 0 | 1 | BF | AC6 | AC5 | AC4 | AC3 | AC2 | AC1 | AC0 |
| Write Data to RAM | 1 | 0 | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
| Read Data from RAM | 1 | 1 | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
| Instruction | Function |
| Clear Display | Write 20H to DDRAM and set DDRAM address to 00H from AC |
| Cursor At Home | Set DDRAM address to 00H from AC and return cursor to its original Position if shifted. The contents of DDRAM are not changed. |
| Entry Mode Set | Assign cursor moving direction and enable the shift of entire display. |
| Display On/Off Control | Set display (D), cursor(C), and Blinking of cursor (B) ON/OFF control bit. |
| Cursor or Display Shift | Set cursor moving and display shifts cursor bit, and the direction, without changing of DDRAM data. |
| Function Set | Sets interface data length (DL: 8-BIT / 4-BIT), number of display lines(N: 2-line / 1-line) and, display font type (F: 5x11dots / 5×8 dots). |
| Set CGRAM Address | Set CGRAM address in address counter. |
| Set DDRAM Address | Set DDRAM address in address counter. |
| Read Busy Flag and Address | Whether during internal operation or not can be known by reading BF. The contents of address counter can also be read. |
| Write Data to RAM | Write data into internal RAM (DDRAM / CGRAM) |
| Read Data from RAM | Reads data from internal RAM (DDRAM / CGRAM). |
Software and Hardware Design
Display the website link www.hificat.com in first line of 1602 LCD.
Display the telephone number 0571-85956028 in second line of 1602 LCD.
Switch to LCD display mode before this experiment.
Schematic Diagram
1602 LCD can communicate with MCU AT89C51 directly.