BPK-000 Serial Interface for Text LCDs
BPK-000 LCD Serial Backpack™ is a generic serial interface for standard text-mode LCDs up to 80 screen characters. It is not needed for the LCDs we sell--all of them have a serial interface installed. BPK-000 may be added to an inexpensive parallel-interface LCD to give it the capabilities of our BPI-216 products.
BPK-000 Features
- Ultralow current requirement: < 0.5mA
- Simple to use with easy programming/formatting
- Chip available for OEM integration
- Deep inventory for no-lead-time delivery
Basic Specifications
| Size | 2.8 x 1.4 in. (71 x 36mm) |
|---|---|
| Power Requirements | 4.8 to 5.5Vdc at < 0.5mA |
| User Connector | 5-pin header, 0.025in. posts on 0.10in. centers |
| Connector Pinout | +5V Gnd Serial Gnd +5V |
| Serial Input | RS-232 (negative swing OK) or inverted TTL |
| *Operating Temperature | 0° to 50° C |
| Initialization | switches LCD power on after good +5V; performs soft init |
| Instruction Prefix | ASCII 254 (0xFE hex) |
| *BPK-000 is designed for use only with commercial temperature-range LCDs, not VFDs or extended-temperature LCDs. These have special requirements (high current or negative bias voltage) that the unit does not support. | |
Installation
Alphanumeric LCDs have a 14-pin interface header with the standard pin assignments listed in the table below. The header is physically arranged in either a single row of 14 solder pads, or 2 rows of 7 pads. BPK-000 has both layouts. Installation just requires soldering the supplied header posts to the LCD, then soldering the Backpack to the posts. Everything lines up, so the installation is simple and secure.
Backlit LCDs may have two additional pads--15 and 16--beyond the basic 14-pin logic interface. This is the power connection for the backlight. Backlight power must be connected separately in accordance with the display's specs; BPK-000 does not have backlight connections.
Shown below is the pinout that the BPK-000 supports, arranged in terms of the 2-rows-of-7 layout. The BPK also supports the straight 1-of-14 layout.
| Pin | Function | Pin | Function |
|---|---|---|---|
| 13 | Data bit 6 | 14 | Data bit 7 |
| 11 | Data bit 4 | 12 | Data bit 5 |
| 9 | Data bit 2 | 10 | Data bit 3 |
| 7 | Data bit 0 | 8 | Data bit 1 |
| 5 | RW (read/write) | 6 | E (enable) |
| 3 | V contrast | 4 | RS (data/instruction reg select) |
| 1 | Vss (ground) | 2 | Vdd (+5V) |
LCD Instructions
Text sent to the BPK-000 prints to the LCD screen. Instructions for clearing the screen, changing the print position, etc. are distinguished from text by the instruction prefix, ASCII 254 (hex 0xFE). The byte after the prefix is processed by the LCD as an instruction. After the instruction byte, subsequent bytes are understood as text until another instruction prefix is received.
| LCD Instruction | ASCII | Hex |
|---|---|---|
| Clear screen | 1 | 0x01 |
| Home cursor | 2 | 0x02 |
| Blank display (retaining data) | 8 | 0x08 |
| Hide cursor | 12 | 0x0C |
| Show underline cursor | 14 | 0x0E |
| Move cursor 1 character left | 16 | 0x10 |
| Move cursor 1 character right | 20 | 0x14 |
| Scroll 1 character left | 24 | 0x18 |
| Scroll 1 character right | 28 | 0x1C |
| Set display address (position cursor) | 128+addr | 0x80+addr |
| Move to leftmost character of 1st line | 128 | 0x80 |
| Move to leftmost character of 2nd line | 192 | 0xC0 |
| Set character-generator address | 64+addr | 0x40+addr |
Accessories
- BSW-CBL wiring harness, 12" power, ground and serial wires to breadboard pins
- PDI-CBL wiring harness, HD-style power connector, DE-9 female for PC internal hookup
- PDX-CBL wiring harness, power, ground wires and DE-9 female for PC external hookup