Rockwell SoniCrafter BT8960 - Manual (Page 66)

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3.0 Registers
3.1 Conventions
Bt8960
Single-Chip 2B1Q Transceiver
N8960DSB
3.2.27 0x22—PLL Modes Register (pll_modes)
clk_freq[1,0] Clock Frequency Select—Read/write binary field specifies one of four data rate ranges for
Bt8960 operation. The 00 state is automatically selected by RST assertion and upon initial
power application. The crystal or external clock frequency must be equal to 32 times the data
rate.
phase_detector_
gain[1,0] Phase Detector Gain—Read/write binary field specifies one of four gain settings for the tim-
ing-recovery phase detector function.
freeze_pll Freeze PLL—Read/write control bit. When set, this bit zeros the proportional term of the loop
compensation filter and disables accumulator updates causing the PLL to hold its current fre-
quency. When cleared, proportional term effects and accumulator updates are enabled allowing
the PLL to track the phase of the incoming data.
pll_gain[1,0] PLL Gain—Read/write binary field specifies the gain (proportional and integral coefficients)
of the loop compensation filter.
7 6 5 4 3 2 1 0
clk_freq[1] clk_freq[0] negate_symbol
phase_detector_
gain[1]
phase_detector_
gain[0]
freeze_pll pll_gain[1] pll_gain[0]
clk_freq[1,0] Range Data Rate
00 221 to 252kbps
01 Above 352 kbps
10 160 to 221 kbps
11 Reserved
phase_detector_gain[1,0] Normalized Gain
00 1
01 2
10 4
11 Reserved
pll_gain[1:0]
Normalized
Proportional Coefficients
Normalized
Integral Coefficients
00 1 1
01 4 32
10 16 256
11 64 4096