Propox EVBlpc213 Series, Руководство пользователя

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8
Push-buttons
The EVBlpc213x board is equipped with four microswitches which can be connected to any lead of the
microcontroller. Pushing a button causes a low state on any port terminal.
R19
10k
R18
10k
R17
10k
R16
10k
+3.3V
SW0
SW1
SW2
SW3
GND
1 2
3 4
J12
SWn
Figure 5
Implementation of push-buttons.
LCD display
MMlpc213x has place for standard 2x16 characters LCD display with HD44780 compatible controller. Display
terminals D4-D7, RS, E, contrast and backlight are led to LCD connector J7. LCD connector is designed in
this way, that it is possible to connect contrast signal to onboard potentiometer with use of jumpers, or with
use of wire to any microcontroller pin, that can generate PWM (through RC low pass filter, which can be built
on prototype area). Similarly, LCD backlight can be permanently turned on by closing jumper, or can be
controlled by any microcontroller pin.
Because LCD connector contains only higher part of display bus, it has to work 4-bit mode. Also, RW line is
permanently connected to ground, what allows only read operation, but it is sufficient to proper operation.
Such approach minimizes required microcontroller port pins to six.
Figure 6
Default LCD configuration
– backlight permanently turned on,
contrast regulated with R5
potentiometer.
C15
100n
GND
+5V
+5V
GND
R4
7k5
LCD_RS
LCD_RW
LCD_E
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
J11
LCD 2x16
Vc
D0
D1
D2
D3
D4
D5
D6
D7
GND
+5V
A
K
+5V
Q2
BC 817
GND
R24
1k
1 2
3 4
5 6
7 8
9 10
J7
+5V
R5
1k
CONTRAST
L
G
T
GND
Figure 7
Connection of LCD display on the board.