Technologic Systems TS-7200, User Manual, Page: 19 / 52

4.2 LCD Header
Table 4.2 LCD Header
Pin-Out
Header Pin Description
1 5V
2 GND
3 LCD_RS
4 Bias
5 LCD_EN
6 LCD_WR
7 LCD_1
8 LCD_0
9 LCD_3
10 LCD_2
11 LCD_5
12 LCD_4
13 LCD_7
14 LCD_6
The LCD Port can be used as 11 additional digital I/O lines or it
can be used to interface to a standard alphanumeric LCD display.
The header has been arranged to allow a 14-pin ribbon cable to
directly connect to industry standard LCD displays. Technologic
Systems has available a 2x24 LCD display with software drivers
for rapid development.
DIO lines LCD_0 thru LCD_7 are a byte-wide port using Port A on
the EP9302 and are accessed via the data register at physical
address location 0x8084_0000. The DDR for this port is at
0x8084_0010.
Since this port is interfacing to a 5V LCD, 1.0 KW resistors have
been added in series between the EP9302 and the LCD_0 thru
LCD_7 pins. This is required since the LCD data bus could be
driving these lines above 3.3V. The series resistors prevent the
LCD from overdriving the EP9302 Port A pins. If using these pins
for general purpose DIO, the current sourcing and sinking
capability of these DIO pins is limited by the 1.0 KW resistors.
LCD_EN, LCD_ RS , and LCD_WR are DIO pins using EP9302
Port H bits 3 through 5 respectively and are accessed via the data
register at physical address location 0x8084_0040. The DDR for
this port is at 0x8084_0044. When these DIO pins are configured
as outputs, they can source 4 mA or sink 8 mA and have logic swings between 3.3V
and ground. When configured as inputs, they have standard TTL level thresholds and
must not be driven below 0 Volts or above 3.3 Volts. These DIO pins have 100 KW bias
resistors biasing these inputs to a logic “1”. It is important not to change the other bit
positions in these Port H registers since the other DIO pins are being used on the TS-
7200. All accesses to these registers should use read-modify-write cycles.
Warning!
LCD pins 3, 5, and 6 use 0-3.3V logic levels. Do not drive these lines to 5V.
Pin 4 on this header (labeled Bias) is a 620 ohm resistor to ground for LCD contrast
biasing.
The 5V power on the LCD header has a 750 mA Poly-Fuse to limit the current.
TS-7200 User's Manual Technologic Systems http://www.embeddedARM.com/
15 12/2004