9

HCMS-29xx Write Cycle Diagram

Control Word 0

display brightness by pulse width modulating the LED

operation or sleep mode.

Internal Display Oscillator and the LED pixel drivers. This

mode is used when the IC needs to be powered up, but

does not need to be active. Current draw in sleep mode

is nearly zero. Data in the Dot Register and Control Words

are retained during sleep mode.

Control Register

The Control Register allows software modification of the

IC’s operation and consists of two independent 7-bit

the two 7-bit control words. Control Word 0 performs

pulse width modulation brightness control, peak pixel

current brightness control, and sleep mode. Control

Word 1 sets serial/simultaneous data out mode, and

external oscillator prescaler. Each function is indepen-

dent of the others.

Control Register Data Loading

Data is loaded into the Control Register, MSB first, ac-

cording to the procedure shown in Table 1 and the

Write Cycle Timing Diagram. First, RS is brought to logic

high and then CE is brought to logic low. Next, each

successive rising CLK edge will shift in the data on the

line is brought to logic high. When CLK goes to logic

low, new data is copied into the selected control word.

Loading data into the Control Register takes place while

the previous control word configures the display.

NOTE:

1. DATA IS COPIED TO THE CONTROL REGISTER OR THE DOT LATCH AND LED OUTPUTS WHEN CE IS HIGH AND CLK IS LOW.

RSH

T

CES

T

CLKH

T

CLKL

T

CEH

T

DS

T

DH

T

CEDO

T

DOUT

T

DOUTP

T

PREVIOUS DATA

NEW DATA

CE

RS

CLK

LED OUTPUTS,

CONTROL

REGISTERS

(SIMULTANEOUS)

OUT

D

D

(SERIAL)

OUT

2

1

3

4

11

12

6

7

8

10

9

5