PDSP1880, PDSP1881, PDSP1882, PDSP1883, PDSP1884

2006-03-30

12

The second routine provides a visual test of the LEDs. This is

accomplished by writing checkered and inversed checkered pat-

terns to the display. Each pattern is displayed for approximately

2.0 sec. During the self test function the display must not be

accessed. The time needed to execute the self test function is cal-

culated by multiplying the clock time by 262,144 (typical

time

≈ 4.6 s). At the end of the self test, the Character RAM is

loaded with blanks; the Control Word Register is set to zeroes

except D5; the Flash RAM is cleared and the UDC Address Regis-

ter is set to all 1.0 sec.

Clear Function (see Figure „Control Word Data Definition“

(page 12) and Table „Clear Function“ (page 12))

Control Word bit, D7 clears the character RAM to 20 hex and the

flash RAM to all zeroes. The RAMs are cleared within three clock

cycles (110 µs minimum, using the internal clock) when D7 is set

to 1. During the clear time the display must not be accessed.

When the clear function is finished, bit 7 of the Control Word RAM

will be reset to a “0”.

Reset Function

The display should be reset on power up of the display

(RST=LOW). When the display is reset, the Character RAM, Flash

RAM, and Control Word Register are cleared.

The display's internal counters are reset. Reset cycle takes three

clock cycles (110 µs minimum using the internal clock). The dis-

play must not be accessed during this time.

To synchronize the flashing and blinking of multiple displays, it is

necessary for the display to use a common clock source and reset

all the displays at the same time to start the internal counters at

the same place.

While RST is low, the display must not be accessed by RD nor

WR.

Control Word Data Definition

Key

C

Clear Function

ST

Self test

BL

Blink function

FL

Flash function

Br

Brightness control

IDCW5161

Function

Blink

Self Test

Function

Brightness Control

D7

D6

D5

D4

D3

D2

D1

D0

D1 D0 Brightness Control

100% Brightness

00

80% Brightness

01

1

53% Brightness

0

1

40% Brightness

1

Disabled

Flash Function

D3

0

Enabled

1

Enabled (overrides Flash Function)

Disabled

Blink Function

D4

1

0

Normal Operation (X = bit ignored)

R

D5

X

Run Self Test, R = Test Result (1 = pass, 0 = fail)

Self Test

Clear Flash RAM & Character RAM (Character RAM = 20 Hex)

Normal Operation

0

1

Clear Function

D7

Clear

Flash

Function

D2

0

0

0

0

27% Brightness

Blank Display

11

1

1

1

0

10

1

0

0

20% Brightness

13% Brightness

0

0

1

D6

Clear Function

CE

WR

FL

A3

A2

A1

A0

D7

D6

D5

D4

D3

D2

D1

D0

Operation

0

0

0

0

1

1

0

0

X

X

X

X

X

X

0

1

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Clear disabled

Clear user RAM, flash RAM

and display

X=don’t care