4/14

MSC1208

¡ Semiconductor

PIN DESCRIPTIONS

Pin

Symbol

Type

42

—

Power Sypply Voltage. A 12V power supply is connected.

Description

20

GND

—

19

Ground. 0V is applied.

Serial data input-output.

Enters the input mode when a "H" level signal is input to DATA ENABLE; enters the

output mode when a "L" level signal is input to DATA ENABLE.

DATA

DATA

ENABLE

I/O

18

I

Serial clock input.

During the "H" level of clock pulse, the input data of the DATA I/O pin (display data or

dimming data) is read, and during the "L" level of clock pulse, the output data (key

swich data) is output to the DATA I/O pin.

Input for the key matrix.

These pins are "L" active. When these keys are in the inactive state, these pins are at

"H" level through the internal pull-up resistors. COL1 to COL3 are for the rotary switch

and COL4 to COL7 are for the push-button switch.

11 to 17

COL1 to 7

I

7 to 10

ROW1 to 4

O

Signal outputs for scanning key matrix.

Normally, ROW1 to ROW4 output a "I" level. Key scanning is executed only once when

a transfer of the rotary switch contact or pressing down or release of the push-button

switch is detected. Key scanning is continued if the rotary switch contact is in the open

state after this one-time scanning. Then, scanning stops when the rotary switch contact

makes connection with any of the selective contacts. After key scanning is stopped,

ROW1 to ROW4 return to a "L" level.

21

OSC

I/O

RC oscillator connection. A capacitor is connected between GND and this pin.

25 to 41,

1 to 6

SEG1 to 23

O

Segment signal output.

Inverted GRID signal output. This signal is connected to an external grid driver

(e.g., PNP transistor) input.

Input for test. Since this pin has as internal a pull-up resistor, leave this pin open or

pull it up for use. When a "L" level signal is input, all segment outputs go on and off

at intervals of 1 second.

23 , 24

GRID1,2

O

22

TEST

I