Texas Instruments 3138 155 232931 - Manual (Page 69)

CC2420
SWRS041B Page 69 of 89
FSCTRL (0x18) - Frequency Synthesizer Control and Status
Bit Field Name Reset R/W Description
15:14 LOCK_THR[1:0] 1 R/W Number of consecutive reference clock periods with successful
synchronisation windows required to indicate lock:
0: 64
1: 128 (recommended)
2: 256
3: 512
13 CAL_DONE 0 R Calibration has been performed since the last time the frequency
synthesizer was turned on.
12 CAL_RUNNING 0 R Calibration status, '1' when calibration in progress and ‘0’
otherwise.
11 LOCK_LENGTH 0 R/W Synchronisation window pulse width:
0: 2 prescaler clock periods (recommended)
1: 4 prescaler clock periods
10 LOCK_STATUS 0 R Frequency synthesizer lock status:
0 : Frequency synthesizer is out of lock
1 : Frequency synthesizer is in lock
9:0 FREQ[9:0] 357
(2405
MHz)
R/W Frequency control word, controlling the RF operating frequency
F
C
. In transmit mode, the local oscillator (LO) frequency equals
F
C
. In receive mode, the LO frequency is 2 MHz below F
C
.
F
C
= 2048 + FREQ[9:0] MHz
See the Frequency and Channel Programming section on page
50 for further information.