Remote Processing RPC-2350 - Manual (Page 64)

CHAPTER 15 GRAPHIC DISPLAY PORT
15-3
Figure 15-2 Jumper W3 detail
lighted pixel (or block) on one layer ca n obliterate
another.
This CAM BASIC can display 3 character sizes. T he 2
larger sizes are considered a graphic.
Each layer can be turned on, off, or flashed.
CONTRAST ADJUSTMENT
There are two contrast adjustment methods for LC
displays. Both use the BIAS pot R30.
Jumper W3 determines if contrast is set only by BIAS
pot R30 or can be also modified in software. Software
control is handy if the display is subjected to wide
tempera ture variations.
Softwar e control u ses analog ou tput channel 1. If this
channel is used for contrast adjustment, then analog
output voltage a nd 4-20 m A. curr ent are no t available
for this cha nnel.
Mechanical Contrast Adjustment
Contr ast set by R30 is fa ctory def ault. W 3[2-3] sets this
condition. See figure 15-2 below for jum per deta il.
Adjust R30 BIAS pot for optimal viewing.
Software Contrast Control
Contrast can be controlled by software using analog
output channel 1.
The con trast should a djusted ma nually at first. Simply
power up the display and run one of the display
program s. Adjust R30 contrast for optimal display.
Then turn off the power and set the jumpers shown
below. (Contr ast voltage at displa y connector J9-5 is
about -18 volts.)
Set the following jumper s:
W3[1-2]
W12[5-7]
Jumper W 3 is set for software control. See F igure 15-2
below for jumper detail. Jumper W12 is set for + /-5V
output from the D/A.
After the board is powered up, execute the following
CAM BASIC statement:
AOT 1,2048
This sets the D/ A output to 0V. This code should also
b e pl a ce d in th e in it ia l iz a ti on s ec t io n of y ou r p ro g r am .
The D/ A has 12 bit resolution. This translates to 4096
possible voltages from -5 to + 5V, or about 2.4 mV /step.
This re solution is far to o fine to be notice d. N oticeable
changes in contrast start in steps of 200 counts. Using
the AOT comma nd, you can step up or dow n to increase
or decre ase screen br ightness.
The following examples show a relative screen change
for different voltage va lues.
AOT 1,3000 Decre ase brightness
AOT 1,2000 Increase br ightness
At some point an increase in brightness swamps out the
contrast.
PRINTING TEXT
The GRA PDE MO. BAS program shows the different
ways of printing all text characters and graphics. Run
this program to see how it work s.
NOTE: Medium and large characters use Flash EPROM
in U3 to store fonts. Make sur e W11 is installed.
There are 3 text sizes: Sm all ( 2.88 mm or 0.11" tall),
m e d iu m ( 5. 7 6 m m or 0 . 2 2" t a ll ) a n d l ar g e (1 7 . 2 8 m m
or 0.68" tall) (sizes are based on 0.36 mm dot pitch).
Standard is small. This font is built into the graphics
controller.
All fonts are fixed space, not proportional. Sm allest font
is 8 x 8 pixels. Medium font is 10 wide by 16 tall. The