ETL9444 datasheet(25/27 Pages) STMICROELECTRONICS

25 / 27 page

= 1 : higher voltage input levels

(”0” = 1.2V, ”1” = 3.6V)

Option 30 : IN Input Levels

same as Option 29

Option 31 : G Input Levels

same as Option 29

Option 32 : SI Input Levels

same as Option 29

Option 33 : RESET Input

= 0 : Schmitt trigger input

= 1 : standard TTL input levels

= 2 : higher voltage input levels

Option 34 : CKO Input Levels (CKO = input Option

2 = 2.3)

same as Option 29

Option 35 COP Bonding

= 0 : ETL9444 (28-pin device)

= 1 : ETL9445 (24-pin device)

= 2 : both 28 and 24 pin versions

TEST MODE (Non-Standard Operation)

The SO output has been configured to provide for

standard test procedures for the custom-program-

med ETL9444. With SO forced to logic ”1”, two test

modes are provided, depending upon the value of

SI :

a. RAM and Internal Logic Test Mode (SI = 1)

b. ROM Test Mode (SI = 0)

These special test modes should not be employed

by the user ; they are intended for manufacturing

test only.

APPLICATION EXAMPLE :

ETL9444 General Controller

Figure 8 shows and interconnect diagram for a

ETL9444 used as a general controller. Operation of

the system is as follows :

1. The L7-L0 outputs are configured as LED Direct

Drive outputs, allowing direct connection to the

segments of the display.

2. The D3-D0 outputs drive the digits of the multi-

plexed display directly and scan the columns of

the 4 x 4 keyboard matrix.

3. The IN3-IN0 inputs are used to input the 4 rows

of the keyboard matrix. Reading the IN lines in

conjunction with the current value of the D out-

puts allows detection, debouncing, and deco-

ding of any one of the 16 keyswitches.

4. CKI is configured as a single-pin oscillator input

allowing system timing to be controlled by a sin-

gle-pin RC network. CKO is therefore available

for use as a general-purpose input.

5. SI is selected as the input to a binary counter in-

put. With SIO used as a binary counter, SO and

SK can be used as general purpose outputs.

6. The 4 bidirectional G I/O ports (G3-G-0) are avai-

lable for use as required by the user’s applica-

tion.

7. Normal reset operation is selected.

Figure 8 : ETL9444 Keyboard/display Interface.

ETL9444/9445–ETL9344/9345

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