RFHCS362G datasheet(19/54 Pages) MICROCHIP

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DS41189B-page 19

rfHCS362G/362F

3.5

RF Enable and Transmitter Interface

The S3/RFENOUT pin of the rfHCS362 can be config-

ured to function as an RF Enable output signal. This is

selected by the RF Enable Output (RFEN) configura-

tion option as described in Section 4.5.13. When

enabled, this pin will be driven HIGH before data is

transmitted through the DATA pin.

The RFENOUT and DATA pins are synchronized to

interface with the transmitter. Figure 3-11 shows the

start-up sequence. A button is debounced and the

EEPROM counter advanced during the power-up delay

(TPU). Then the RFENOUT pin goes high to enable the

transmitter. The DATA output is delayed to give the

transmitter crystal oscillator and PLL time to startup

(TPLL). The RFENOUT signal will go LOW one guard

time after the end of the last code word.

When the RF Enable output is selected, the S3 pin can

still be used as a button input. However, only minimum

code words will be transmitted. An alternative solution

for more than three push buttons can be the switching

diode circuit described in Section 1.2.

In typical implementations of the rfHCS362G/362F, the

encoder RFENOUT pin is connected to the transmitter

RFENIN pin.

FIGURE 3-11: PLL INTERFACE

S[3210]

RFENOUT

DATA

TPLL

Guard Time

1st CODE WORD

Button Press

Button Release

2nd CODE WORD

TPU

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