MICRF507 Datasheet, PDF (33/46 Pages) Micrel Semiconductor – 470MHz to 510MHz Low-Power FSK Transceiver with +10dBm Power Amplifier

Micrel, Inc.
MICRF507
System Modes and Initialization
Start-up and Initialization
After supply voltage is applied to the MICRF507, a power
on reset period elapses during which it should be
considered to be in an unknown state. The microcontroller
should wait until power on reset is completed. See
“Power-On Reset” subsection within the “Control (3-wire)
Interface” section. After power-on is completed, all 22
writeable registers must be correctly initialized before
operation of the MICRF507. Write only non-zero values to
the M0, N0, M1, and N1 fields.
Modes of Operation
Mode1 Mode0 State
0
0
Power
down
0
1
Standby
1
0
Receive
1
1
Transmit
Comments
Keeps register configuration
Only crystal oscillator
running
Full receive
Full transmit except PA
state
Table 20. Main Mode Bits
Mode Transitions
To go from power down mode to either receive or transmit
mode, the MICRF507 needs to go through the standby
mode first. This is to ensure that the crystal oscillator starts
up correctly. Once the crystal oscillator settles, the
MICRF507 can go to receive or transmit mode.
When the mode has been changed to Transmit or
Receive, or when the power amplifier has been enabled,
the synthesizer must be allowed to stabilize. See “Lock
Detect” section.
When using VCO modulation; after MICRF507 has been
put in transmit mode, the microcontroller will tri-state the
driver connected to DATAIXO pin to leave that pin floating
until the microcontroller begins sending data. This is
because in transmit mode, the modulator is disabled while
the DATAIXO pin is floating (a weak voltage divider sets its
level at Vdd/2) in order to prevent a performance-
degrading transient when message transmission begins.
Below, “write to registers” means writing a complete
control word, or writing just to registers that need to
change.
Transition to transmit mode:
• Write to registers, setting transmit mode, and other
changes as needed; set/keep PA off (to reduce
spurious emissions). This makes DATAIXO an
input.
• Write to registers setting PA on (this requires
updating Register 0 only).
• Wait for LD.
• Enable the microcontroller’s pin as an output
driving DATAIXO and begin sending the transmit
bitstream.
• After the last bit is transmitted return the
microcontroller’s pin to being an input.
Transition to receive mode:
• Have the microcontroller’s DATAIXO driver
disabled.
• Write to registers setting receive mode and other
changes as needed.
• Wait for LD. Or, if desired, commence checking
the received bitstream for a valid message without
waiting.
Field Name
Mode
OUTS
Number
of bits
2
4
Location
of bits
Reg0[2:1]
Reg2[3:0]
Description
Main mode selection
Test pins output
Table 21. Register Bit Fields for System Functions
Reference
Table 20
Table 28
March 2010
33
M9999-032210-B