Contrast Adjustments For All Boards - Rabbit RCM3365 User Manual

C.2 Contrast Adjustments for All Boards
Starting in 2005, LCD/keypad modules were factory-configured to optimize their contrast
based on the voltage of the system they would be used in. Be sure to select a KDU3V
LCD/keypad module for use with the Prototyping Board for the RCM3365/RCM3375 —
these modules operate at 3.3 V. You may adjust the contrast using the potentiometer at R2
as shown in Figure C-3. LCD/keypad modules configured for 5 V may be used with the
3.3 V Prototyping Board, but the backlight will be dim.
Contrast
Adjustment
J5
3
4
Figure C-3. LCD/Keypad Module Contrast Adjustments
You can set the contrast on the LCD display of pre-2005 LCD/keypad modules by adjust-
ing the potentiometer at R2 or by setting the voltage for 3.3 V by connecting the jumper
across pins 3–4 on header J5 as shown in Figure C-3. Only one of these two options is
available on these LCD/keypad modules.
NOTE: Older LCD/keypad modules that do not have a header at J5 or a contrast adjust-
ment potentiometer at R2 are limited to operate only at 5 V, and will not work with the
Prototyping Board for the RCM3365/RCM3375. The older LCD/keypad modules are
no longer being sold.
User's Manual
Description
Header
2.8 V
J5
3.3 V
5 V
R2
U3
LCD1
Q1
J5
R25
1
R8
R26
2
R11 R13
J5
3 1
Q4
Q6
4 2
OTHER
LP3500
3.3 V 2.8 V
n.c. = 5 V
KP1
RN1
C17
Pins
Connected
1–2
3–4
n.c.
D2 C1
D1 JP1
C4
R3
C6 U1
U2
C9
C7 R4
R5
C11
U4
J1
R14 R10 R9 R12
R15
Q2
Q7 Q5
Q8
U5
U6
J2
U7 C14
DISPLAY
J4
Factory
Default
×
CR1
C13
C12
BOARD
105