9

FN3159.3

September 15, 2015

Application Examples

8-Digit Microprocessor Display Application

Figure 9 shows a display interface using the lCM7218A/B

with an 8048 family microcontroller. The 8 bit data bus

(DB0/DB7-lD0/ID7) transfers control and data information to

the 7218 display interface on successive WRITE pulses. The

MODE input to the 7218 is connected to one of the I/O port

pins on the microcontroller, When MODE is high a control

word is transferred; when MODE is low data is transtered.

Sequential locations in the 8-byte static memory are

automatically loaded on each successive WRITE pulse.

After eight WRITE pulses have occurred, further pulses are

ignored until a new control word is transferred (See

Figure 5). This also allows writing to other peripheral devices

without disturbing the lCM7218A/B.

16-Digit Microprocessor Display

In this application (see Figure 10), both lCM7218s are

addressed simultaneously with a 3 bit word, DA2-DA0.

Display data from the 8048 I/O bus (DB7-D80) is transferred

to both lCM7218s simultaneously.

The display digits from both lCM7218s are interleaved to

allow adjacent pairs of digits to be loaded simultaneously

from a single 8 bit data bus.

Decimal point information is supplied to the ICM7218s from

the processor on port lines P26 and P27.

No Decode Application

The lCM7218 can also be used as a microprocessor based

LED status panel driver. The microprocessor selected

control word must include "No Decode" and "Data Coming".

The processor writes "Ones" and "Zeroes" into the lCM7218

which in turn directly drives appropriate discrete LEDs. LED

indicators can be red or green (8 segments x 8 digits = 64

dots/2 per red or green = 32 channels).

FIGURE 9. 8-DIGIT MICROPROCESSOR DISPLAY

ICM7218