RFM12B_15 Datasheet, PDF (17/41 Pages) List of Unclassifed Manufacturers – Universal ISM Band FSK Transceiver

RFM12B
3. Frequency Setting Command
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 0 1 0 f11 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1 f0
POR
A680h
The 12-bit parameter F (bits f11 to f0) should be in the range
of 96 and 3903. When F value sent is out of range, the
previous value is kept. The synthesizer center frequency f0
can be calculated as:
f0 = 10 · C1 · (C2 + F/4000) [MHz]
The constants C1 and C2 are determined by
the selected band as:
Band [MHz] C1 C2
433
1 43
868
2 43
915
3 30
Band
433 MHz
868 MHz
915 MHz
Minimum Frequency
430.2400 MHz
860.4800 MHz
900.7200 MHz
Maximum Frequency
439.7575 MHz
879.5150 MHZ
929.2725 MHz
PLL Frequency Step
2.5 kHz
5.0 kHz
7.5 kHz
4. Data Rate Command
Bit 15 14 13 12 11 10 9
1100011
876543210
0 cs r6 r5 r4 r3 r2 r1 r0
POR
C623h
The actual bit rate in transmit mode and the expected bit rate of the received data stream in receive mode is determined by the 7-bit
parameter R (bits r6 to r0) and bit cs.
BR = 10000 / 29 / (R+1) / (1+cs · 7) [kbps]
In the receiver set R according to the next function:
R= (10000 / 29 / (1+cs · 7) / BR) – 1, where BR is the expected bit rate in kbps.
Apart from setting custom values, the standard bit rates from 600 bps to 115.2 kbps can be approximated with small error.
Data rate accuracy requirements:
Clock recovery in slow mode: ΔBR/BR < 1/(29 · Nbit)
Clock recovery in fast mode: ΔBR/BR < 3/(29 · Nbit)
BR is the bit rate set in the receiver and ΔBR is the bit rate difference between the transmitter and the receiver. Nbit is the maximum
number of consecutive ones or zeros in the data stream. It is recommended for long data packets to include enough 1/0 and 0/1
transitions, and to be careful to use the same division ratio in the receiver and in the transmitter.
5. Receiver Control Command
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 0 0 1 0 p16 d1 d0 i2 i1 i0 g1 g0 r2 r1 r0
Bit 10 (p16): Pin 16 function select
p16
Function of pin 16
0
Interrupt input
1
VDI output
POR
9080h
17
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