RF42/43
3.2.3. TX State
The TX state may be entered from any of the IDLE modes when the txon bit is set to 1 in "Register 07h. Operating
Mode and Function Control 1". A built-in sequencer takes care of all the actions required to transition between states
from enabling the crystal oscillator to ramping up the PA to prevent unwanted spectral splatter. The following sequence
of events will occur automatically when going from STANDBY mode to TX mode by setting the txon bit.
1. Enable the Main Digital LDO and the Analog LDOs.
2. Start up crystal oscillator and wait until ready (controlled by timer).
3. Enable PLL.
4. Calibrate VCO (this action is skipped when the vcocal bit is ―0‖, default value is ―1‖).
5. Wait until PLL settles to required transmit frequency (controlled by timer).
6. Activate Power Amplifier and wait until power ramping is completed (controlled by timer).
7. Transmit Packet.
The first few steps may be eliminated depending on which IDLE mode the chip is configured to prior to setting thetxon
bit. By default, the VCO and PLL are calibrated every time the PLL is enabled. If the ambient temperature isconstant
and the same frequency band is being used these functions may be skipped by setting the appropriate bits in "Register
55h. Calibration Control".
3.2.4. Device Status
D7
D6
D5
D4
D3 D2 D1
D0
POR Def.
Add R/W Function/Description
02 Device Status
R
ffovfl ffunfl Reserved Reserved
cps[1] cps[0]
——
The operational status of the chip can be read from "Register 02h. Device Status".
17
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