Silan

Semiconductors

SC6121

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 1.2

2002-02-28

5

Pull-down resistors are connected between the Key Input and Vss Pins. When more than one key (except the

double key combinations: K21+22, K21+23, K21+24) are pressed simultaneously, the transmission output stops.

Two key inputs are regarded as being pressed simultaneously when the time interval between these two key

entries is less than 36ms.

The order of priority given to two key inputs with a time interval of more than 36ms is on a First-Pressed-First-

Served or Longer-Pressed-First-Served Basis.

When a key is pressed, the custom and data codes are read. 36ms later, the Remote (REM) Output is activated.

When the key is kept depressed during this 36ms, one transmission is outputted. If the key is depressed for more

than 108ms, then the only the leader code is transmitted continuously.

4. DOUBLE KEY OPERATION

Double Key Operation is useful for operations such as tape deck recording. The following table shows the Key

Data corresponding to the double keys pressed. Also refer to the Key Input Section.

The Double Key operation forms are as follows:

Key

D0

D1

D2

D3

D4

D5

D6

D7

K21+K22

1

010

110

0/1

K21+K23

0

110

110

0/1

K21+K24

1

110

110

0/1

K21

K22to24

t >126ms

K21 Transmission

D5+K22 to 24

Transmission

OPERATION

K21

K22to24

push

push

36ms< t <126ms

K21 Transmission

No Transmission

NO OPERATION

K21

K22to24

-36ms< t < 36ms

No Transmission

NO OPERATION

K21

K22to24

t >126ms

NO OPERATION

K22to24Transmission

No Transmission