SI4031-B1-FM Silicon Laboratories Inc, SI4031-B1-FM Datasheet - Page 37

• Manufacturer Part Number: SI4031-B1-FM
• Description: IC TX 240-930MHZ -8-13DB 20VQFN
• Manufacturer: Silicon Laboratories Inc
• Type: ISM Transmitterr

Specifications of SI4031-B1-FM

• Package / Case: 20-VQFN
• Frequency: 240MHz ~ 930MHz
• Applications: General Purpose
• Modulation Or Protocol: FSK, GFSK, OOK
• Data Rate - Maximum: 256 kbps
• Power - Output: 13dBm
• Current - Transmitting: 30mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 1.8 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Operating Frequency: 240 MHz to 930 MHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 1.8 V to 3.6 V
• Supply Current: 30 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

6.4. Data Whitening, Manchester Encoding, and CRC
Data whitening can be used to avoid extended sequences of 0s or 1s in the transmitted data stream to achieve a
more uniform spectrum. When enabled, the payload data bits are XORed with a pseudorandom sequence output
from the built-in PN9 generator. The generator is initialized at the beginning of the payload. The receiver recovers
the original data by repeating this operation. Manchester encoding can be used to ensure a dc-free transmission
and good synchronization properties. When Manchester encoding is used, the effective datarate is unchanged but
the actual datarate (preamble length, etc.) is doubled due to the nature of the encoding. The effective datarate
when using Manchester encoding is limited to 128 kbps. The implementation of Manchester encoding is shown in
Figure 15. Data whitening and Manchester encoding can be selected with "Register 70h. Modulation Mode Control
1". The CRC is configured via "Register 30h. Data Access Control". Figure 14 demonstrates the portions of the
packet which have Manchester encoding, data whitening, and CRC applied. CRC can be applied to only the data
portion of the packet or to the data, packet length and header fields. Figure 15 provides an example of how the
Manchester encoding is done and also the use of the Manchester invert (enmaniv) function.
6.5. Synchronization Word Configuration
The synchronization word length can be configured in Reg 33h, synclen[1:0]. The expected or transmitted sync
word can be configured from 1 to 4 bytes as defined below:




The sync is transmitted in the following sequence: sync 3sync 2sync 1sync 0. The sync word values can be
programmed in Registers 36h–39h.
synclen[1:0] = 00—Transmitted Synchronization Word (sync word) 3.
synclen[1:0] = 01—Transmitted Synchronization Word 3 first, followed by sync word 2.
synclen[1:0] = 10—Transmitted Synchronization Word 3 first, followed by sync word 2, followed by sync word 1.
synclen[1:0] = 1—Transmitted Synchronization Word 3 first, followed by sync word 2, followed by sync word 1,
followed by sync word 0.
1
0
1
0
Figure 14. Operation of Data Whitening, Manchester Encoding, and CRC
1
0
Preamble = 0xFF
Preamble = 0x00
1
0
Preamble
1
0
1
0
Figure 15. Manchester Coding Example
1
0
Sync
1
0
Address
0
0
Header/
First 4bits of the synch. word = 0x2
First 4bits of the synch. word = 0x2
Manchester
Rev 1.1
0
0
0
0
Length
CRC
PK
Whitening
1
1
(Over data only)
0
0
Data
CRC
Data before Manchester
Data after Machester ( manppol = 1, enmaninv = 0)
Data after Machester ( manppol = 1, enmaninv = 1)
Data before Manchester
Data after Machester ( manppol = 0, enmaninv = 0)
Data after Machester ( manppol = 0, enmaninv = 1)
Si4030/31/32-B1
CRC
37