Si1000/1/2/3/4/5
TX Modulation Time Domain Waveforms -- FSK vs. GFSK
1.5
TX Modulation Spectrum -- FSK vs GFSK (Continuous PRBS)
-20
1.0
0.5
-40
-60
-80
0.0
-0.5
-1.0
-100
-20
-1.5
1.0
-40
-60
0.5
0.0
-80
-0.5
-1.0
-100
-250 -200 -150 -100
-50
0
50
100
150
200
250
0
50
100 150 200 250 300 350 400 450 500
time, usec
freq, KHz
DataRate
64000.0
TxDev
BT_Filter
0.5
ModIndex
1.0
32000.0
Figure 23.6. FSK vs. GFSK Spectrums
23.4.2. Modulation Data Source
The transceiver may be configured to obtain its modulation data from one of three different sources: FIFO
mode, Direct Mode, and from a PN9 mode. In Direct Mode, the TX modulation data may be obtained from
several different input pins. These options are set through the dtmod[1:0] field in "Register 71h. Modulation
Mode Control 2".
D7
D6
D5
D4
D3
D2
D1
D0
POR Def.
Add R/W
Function/
Description
71 R/W
Modulation
Mode
trclk[1] trclk[0] dtmod[1] dtmod[0] eninv fd[8] modtyp[1] modtyp[0]
00h
Control 2
dtmod[1:0]
Data Source
00
01
10
11
Direct Mode using TX/RX Data via GPIO pin (GPIO configuration required)
Direct Mode using TX/RX Data via SDI pin (only when nSEL is high)
FIFO Mode
PN9 (internally generated)
23.4.2.1. FIFO Mode
In FIFO mode, the transmit and receive data is stored in integrated FIFO register memory. The FIFOs are
accessed via "Register 7Fh. FIFO Access," and are most efficiently accessed with burst read/write opera-
tion.
In TX mode, the data bytes stored in FIFO memory are "packaged" together with other fields and bytes of
information to construct the final transmit packet structure. These other potential fields include the Pream-
ble, Sync word, Header, CRC checksum, etc. The configuration of the packet structure in TX mode is
252
Rev. 1.0
SILICON [ SILICON ]
