40x4 lcd character display:
Features:
This is 40x4 character lcd display, that with 4 lines of 40 characters, with LCD driver chips on the PCB board,
it is widely used for many industrial display, high contrast, wide temperature, MPU interface. ROHS.
LCD mode: stn lcd display, yellow-green mode. ( black-white mode, blue mode optional)
Characters: 4 lines x 40 characters
Controller IC: SPLC780D or Equivalent
COB structure (Chip on board)
Viewing angle: 6 o'clock direction
Interface: 6800 serial 8-bit/4 bit MPU interface
Backlight: Yellow LED or white colors LED
Operating Temperature range: -20 to +70 degree
Storage Temperature range: -30 to +80 degree
ITEM
|
Description
|
Unit
|
Module size
|
190.0x54.0x14.5
|
mm
|
View area
|
147x29.5
|
mm
|
Number of Character
|
40x4
|
lines
|
Character Size
|
/
|
mm
|
Character Pitch
|
/
|
mm
|
40x4 pin assignment — 18 pins, dual enable
This module carries two HD44780-compatible controller dies behind a single 18-pin interface. Note that the order is not the usual character-LCD order: the data lines come first and the power pins sit in the middle, so a harness wired for a 16x2 or 20x4 will not work unmodified.
| Pin | Symbol | Function |
|---|
| 1 – 4 | DB0 – DB3 | Data bus, low nibble (used alone in 4-bit mode) |
| 5 – 8 | DB4 – DB7 | Data bus, high nibble |
| 9 | E1 | Enable for controller 1 — lines 1 and 2 |
| 10 | R/W | H: read, L: write |
| 11 | RS | H: data, L: instruction |
| 12 | VO | Contrast adjust |
| 13 | VSS | Signal ground |
| 14 | VDD | Logic supply, +5 V |
| 15 | E2 | Enable for controller 2 — lines 3 and 4 |
| 16 | NC | No connection |
| 17 | LEDA | Backlight anode |
| 18 | LEDK | Backlight cathode |
Wiring note: RS, R/W and DB4 – DB7 are shared by both controllers; only E1 and E2 differ. A 4-bit interface needs 8 MCU pins, and every write must pulse the enable of the half being addressed — the most common fault on a 40x4 is text appearing on only two of the four lines.
40x4 DDRAM address map
Both controllers hold two lines of 40 characters at the same addresses; the enable line decides which half you are writing to.
| Display line | Controller | Enable | First char | Last char |
|---|
| Line 1 | IC1 | E1 | 0x00 | 0x27 |
| Line 2 | IC1 | E1 | 0x40 | 0x67 |
| Line 3 | IC2 | E2 | 0x00 | 0x27 |
| Line 4 | IC2 | E2 | 0x40 | 0x67 |
Lines 3 and 4 reuse the addresses of lines 1 and 2 rather than continuing at 0x28, so a generic single-controller library will not reach the bottom half without handling the second enable.
The wider picture — 4-bit wiring, contrast, backlight options and custom pinouts — is covered in the Character LCD Pinout Guide.
