MICRF507 datasheet(33/47 Pages) MICREL

33 / 47 page

Micrel, Inc.

MICRF507

October 2, 2013

Revision 2.2

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

Comments

Power

down

Keeps register configuration

Standby

Only crystal oscillator

running

Receive

Full receive

Transmit

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

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

Number

of bits

Location

of bits

Description

Reference

Mode

Reg0[2:1]

Main mode selection

Table 20

OUTS

Reg2[3:0]

Test pins output

Table 28

Table 21. Register Bit Fields for System Functions

MICRF507 Datasheet(PDF) 33 Page - Micrel Semiconductor

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