Datasheet

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SX1272/73
WIRELESS, SENSING & TIMING DATASHEET
Rev. 2 - July 2014
©2014 Semtech Corporation
4.2. FSK/OOK Modem
4.2.1. Bit Rate Setting
The bit rate setting is referenced to the crystal oscillator and provides a precise means of setting the bit rate (or equivalently
chip) rate of the radio. In continuous transmit mode (Section
4.2.13) the data stream to be transmitted can be input directly
to the modulator via pin 9 (DIO2/DATA) asynchronously, unless Gaussian filtering is used, in which case the DCLK signal
on pin 10 (DIO1/DCLK) is used to clock-in the data stream. See section
4.2.2.3 for details of the Gaussian filter.
In Packet mode or in Continuous mode with Gaussian filtering enabled, the Bit Rate (BR) is controlled by bits BitRate in
RegBitrateMsb and RegBitrateLsb
Note: BitrateFrac bits have no effect (i.e may be considered equal to 0) in OOK modulation mode.
The quantity BitrateFrac is hence designed to allow very high precision (max. 250 ppm programing resolution) for any
bitrate in the programmable range.
Tab le 18 below shows a range of standard bitrates and the accuracy to within which
they may be attained.
Table 18 Bit Rate Examples
Type
BitRate
(15:8)
BitRate
(7:0)
(G)FSK
(G)MSK
OOK
Actual BR
(b/s)
Classical modem baud rates
(multiples of 1.2 kbps)
0x68 0x2B 1.2 kbps 1.2 kbps 1200.015
0x34 0x15 2.4 kbps 2.4 kbps 2400.060
0x1A 0x0B 4.8 kbps 4.8 kbps 4799.760
0x0D 0x05 9.6 kbps 9.6 kbps 9600.960
0x06 0x83 19.2 kbps 19.2 kbps 19196.16
0x03 0x41 38.4 kbps 38415.36
0x01 0xA1 76.8 kbps 76738.60
0x00 0xD0 153.6 kbps 153846.1
Classical modem baud rates
(multiples of 0.9 kbps)
0x02 0x2C 57.6 kbps 57553.95
0x01 0x16 115.2 kbps 115107.9
BitRate
FXOSC
BitRate 15 0(,)
BitrateFrac
16
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