Rainbow Electronics RA01 - Manual (Page 14)

RA01
Version: 1.0 Date: 10/8/2008
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10. Extended Features Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 POR
1 0 1 1 0 0 0 0 exlp ctls 0 dcal bw1 bw0 f5 f4 B0CAh
Bit 7 < exlp >: Enables low power mode for the crystal oscillator.
Bit 6 < ctls >: Clock tail selection bit. Setting this bit selects 512 bit long clock tail instead of the default 128 bit length.
Bit 4 < dcal >: Disables the wake-up timer auto calibration.
Bit 3-2 <
bw1:bw0 >: Select the bandwidth of the PLL.
bw1 bw0 PLL bandwidth
0 0 15 kHz
0 1 30 kHz
1 0 60 kHz
1 1 120 kHz
Bit 1-0 < f5:f4 >: Upper two bits for selecting the 64 bit FIFO IT level together with the f3-f0 bits in the Output and
FIFO Mode Command.
11. Low Duty Cycle Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 POR
1 0 1 1 0 0 0 0 d6 d5 d4 d3 d2 d1 d0 enld B0CAh
Bit 7-1 < d6:d1 >: The Duty-Cycle can be calculated by using D ( d6 to d0 ) and M. (M is parameter in a Wake-Up
Timer Command .)
Duty-Cycle= (D * 2 +1) / M *100%
Bit 0 < enld >: Enables the low duty cycle operation of the receiver.
12. Demodulator Setting Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 POR
1 0 1 1 0 0 0 0 tc1 tc0 0 0 0 0 0 0 D000h
Bit 7-6 < tc1:tc0 >: Select the time constant of the demodulator
tc1 tc0 Time constant
0 0 Fast
1 1 Middle
1 0 Slow
1 1 Reserved
The table shows the optimal filter capacitor values for different popular data rates:
Data Rate [kbps] Manchester 2.4 4.8 9.6 19.2 38.4 >38.4
Data Rate [kbps] NRZ - 2.4 4.8 9.6 19.2 >19.2
Recommended Capacitor on pin15 ( FILC) [pF] 330 330 220 100 27 0
Optimal setting Slow Slow Middle Middle Fast Fast
Note: Manchester coding doubles the bandwidth requirement compared to NRZ.