RFHCS362F Datasheet, PDF (20/60 Pages) Microchip Technology – Code Hopping Encoder with UHF ASK/FSK Transmitter

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
FIGURE 3-11: PLL INTERFACE
Button Press
S[3210]
RFENOUT
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.
Button Release
DATA
TPU TPLL
1st CODE WORD
TG
2nd CODE WORD
Guard Time
DS41189A-page 20
Preliminary
© 2002 Microchip Technology Inc.