Freescale Semiconductor, Inc.
PLL Tuned UHF Transmitter Module
16.7.2 Extended Control Mode
Driving the MODE pin through the microcontroller allows:
•
Selection of the modulation type to perform the Manchester
coding on chip
•
Tighter control of the power consumption
An example of extended control mode is:
1. The MODE pin switches on the microprocessor clock
NOTE: Only the parts of the circuit necessary to perform this function are
switched on, so the battery current is low (about 1 mA, depending on the
load on the UPCLK line).
2. PLLEN goes to 1, which maintains the microprocessor clock on
and additionally switches on the UHF PLL, operating at a
frequency defined by the crystal frequency and the band option.
3. The circuit now uses the level of the MODE pin when the first rising
edge on DATA arrives and latches the circuit in OOK or FSK
transmission if MODE is 0 or 1, respectively. This latch is locked
until PLLEN is reset to 0.
4. After the modulation type has been chosen on the first DATA
edge, the MODE pin becomes a data clock input and performs an
XOR function with the DATA signal allowing Manchester coding.
NOTE: The XOR function can be avoided by keeping MODE at 0. Keeping
MODE at 1 would invert the transmitted data.
Figure 16-3 and Figure 16-4 illustrate these two modes of operation.
In Figure 16-3 the OOK mode is selected and Manchester coding
capability is not used. MODE must go high before PLLEN goes low at
the end of the transmission to avoid switching the device into sleep
mode. Between these two events, the RF output will be switched on if
DATA is low. If the duration is short, this is generally negligible.
In Figure 16-4, FSK is selected and Manchester coding capability is
used.
Advance Information
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MC68HC908RFRK2
MOTOROLA
PLL Tuned UHF Transmitter Module
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