PDSP2110, PDSP2111, PDSP2112, PDSP2113, PDSP2114

2006-01-23

10

Power up Sequence

Upon power up display will come on at random. Thus the display

should be reset on power-up. The reset will clear the Flash RAM,

Control Word Register and reset the internal counter. All the dig-

its will show blanks and display brightness level will be 100%.

Microprocessor Interface

The interface to a microprocessor is through the 8-bit data bus

(D0-D7), the 4-bit address bus (A0-A3) and control lines FL, CE

and WR.

To write data (ASCII/ Control Word) into the display CE should be

held low, address and data signals stable and WR should be

brought low.

The Control Word is decoded by the Control Word Decode Logic.

Each code has a different function. The code for display brightness

changes the duty cycle for the column drivers. The peak LED cur-

rent stays the same but the average LED current diminishes

depending on the intensity level.

The character Flash Enable causes 2.0 Hz coming out of the

counter to be ANDED with column drive signal and makes the col-

umn driver to cycle at 2.0 Hz. Thus the character flashes at 2.0 Hz.

The display Blink works the same way as the Flash Enable but

causes all twenty column drivers to cycle at 2.0 Hz thereby making

all eight digits to blink at 2.0 Hz.

The Lamp Test causes the column drivers to run at 1/2 duty cycle

thus all the LEDs in all eight digits turn on at 50% intensity.

Clear bit clears the character RAM and writes a blank into the dis-

play memory. It however does not clear the control word.

ASCII Data or Control Word Data can be written into the display at

this point. For multiple display operation, CLK I/O must be properly

selected. CLK I/O will output the internal clock if CLKSEL=1, or will

allow input from an external clock if CLKSEL=0.

Data Input Commands

Signals

CE

WR

FL

A3

A2

A1

A0

Operation

1

X

XX

XX

X

X

1

XX

XX

X

No operation

No operation

0

0

10

00

0

Write Control Register

0

0

11

00

0

0

0

11

00

1

0

0

11

01

0

0

0

11

01

1

0

0

11

10

0

0

0

11

10

1

0

1

11

10

0

0

0

11

11

1

Digit 0 (left)

Digit 1

Digit 2

Digit 3

Digit 4

Digit 5

Digit 6

Digit 7 (right)

Write display data to

user RAM and Page

Select Register

D0–D6=ASCII Data

D7=0 Select ROM 1

D7=1 Select ROM 2

0

0

0X

00

0

0

0

0X

00

1

0

0

0X

01

0

0

0

0X

11

1

0

0

0X

10

0

0

0

0X

10

1

0

0

0X

11

0

0

0

0X

11

1

Digit 0 (left)

Digit 1

Digit 2

Digit 3

Digit 4

Digit 5

Digit 6

Digit 7 (right)

Write Flash RAM Register

D0=0 Flashing Charac. off

D0=1 Flashing Charac. on

D1–D7=X

X=Don’t care