Lcd Interface - Technologic Systems TS-5700 User Manual

TS-5700 User's Manual

7 LCD Interface

A 14-pin LCD connector is provided on the TS-5700 for interfacing with standard
alphanumeric LCD displays. These displays use a common controller, the Hitachi HD44780
or equivalent. While software written for the HD44780 will work with all displays using the
controller, the cable needed is dependent on the display used. For most displays, a straight-
through type ribbon cable can be used. The connector on the LCD display is typically
mounted on the backside of the display.
Warning:
Using an incorrect cable or mounting the LCD connector on the front-side can result in a reverse power polarity
and can damage the LCD display. Please refer to your LCD data sheets for in-depth information.
The TS-5700 BIOS incorporates a fairly complete set of INT10h
video routines that work with the LCD. Once the LCD has been
enabled (INT15h/Func B042h – see Appendix E below)
The LCD can be written to as the standard I/O device. This means
that software can be developed and debugged using standard I/O
calls, and the executable will work with LCD, VGA video, or
redirected COM port.
I/O addresses 72h and 73h are used to access the LCD. Table 7a
shows the header pin-out, while Table 7b lists the LCD signals. The
section below will briefly describe the LCD interface signals. The
LCD can be controlled directly by software at these addresses.
The register select signal is simply the buffered A0 address line.
Thus, reads and writes to 72h cause register select to be low, and
those to 73h cause it to be high. Generally the LCD uses this line to
separate data bytes from command bytes. See your LCD data sheet
for details.
The LCD Write# signal is an active low write enable line.
LCD Enable is an active high signal, raised whenever the LCD
addresses are being read or written.
D0 – D7 are bi-directional, buffered copies of the data bus and carry all data and commands to the LCD.
Table 7b is not the standard pin-outs given for LCD displays. But this pin-out allows a standard ribbon cable to
be used when the ribbon cable is attached to the backside of the LCD.
Example LCD code is available at:
Technologic Systems
See the Section 18 for more information.
ftp://ftp.embeddedarm.com/ts-x86-sbc/old-downloads/UTIL.ZIP
Pin Function
1 LCD 5V
2 LCD GND
3 LCD_RS
4 Bias
5 LCD_EN
6 LCD_WR# Active low Write
7 LCD_D1
8 LCD_D0
9 LCD_D3
10 LCD_D2
11 LCD_D5
12 LCD_D4
13 LCD_D7
14 LCD_D6
13
http://embeddedARM.com/
Table 7a LCD Header
Pinout
2 4 6 8 10 12 14
1 3 5 7 9
Table 7b LCD Header Signals
Comments
Register Select (Buffered AO)
680 Ohm to GND
Active high Enable
D0-D7 Buffered
bi-directional data bus
5/2009
11 13