Remote-processing RPC-2350 Bedienungsanleitung PDF herunterladen (Seite 64)

CHAPTER 15 GRAPHIC DISPLAY PORT

15-3

Figure 15-2 Jumper W3 detail

lighted pixel (or block) on one layer can obliterate

another.

This CAM BASIC can display 3 character sizes. The 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

temperature variations.

Software control uses analog output channel 1. If this

channel is used for contrast adjustment, then analog

output voltage and 4-20 mA. curr ent are no t available

for this channel.

Mechanical Contrast Adjustment

Contrast set by R30 is factory def ault. W 3[2-3] sets this

condition. See figure 15-2 below for jum per detail.

Adjust R30 BIAS pot for optimal viewing.

Software Contrast Control

Contrast can be controlled by software using analog

output channel 1.

The contrast should adjusted manually at first. Simply

power up the display and run one of the display

programs. Adjust R30 contrast for optimal display.

Then turn off the power and set the jumpers shown

below. (Contr ast voltage at display connector J9-5 is

about -18 volts.)

Set the following jumpers:

W3[1-2]

W12[5-7]

Jumper W3 is set for software control. See Figure 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

be placed in the initialization section of your program.

The D/A has 12 bit resolution. This translates to 4096

possible voltages from -5 to + 5V, or about 2.4 mV/step.

This resolution is far too fine to be noticed. N oticeable

changes in contrast start in steps of 200 counts. Using

the AOT command, you can step up or down to increase

or decrease screen brightness.

The following examples show a relative screen change

for different voltage values.

AOT 1,3000 Decrease brightness

AOT 1,2000 Increase br ightness

At some point an increase in brightness swamps out the

contrast.

PRINTING TEXT

The GRAPDEMO. BAS program shows the different

ways of printing all text characters and graphics. Run

this program to see how it works.

NOTE: Medium and large characters use Flash EPROM

in U3 to store fonts. Make sure W11 is installed.

There are 3 text sizes: Small ( 2.88 mm or 0.11" tall),

medium ( 5.76 mm or 0.22" tall) and large (17.28 mm

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

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