si4420 Silicon Laboratories, si4420 Datasheet - Page 14

• Manufacturer Part Number: si4420
• Description: Si4420 Universal Ism Band Fsk Transceiver
• Manufacturer: Silicon Laboratories

3. Frequency Setting Command
4. Data Rate Command
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:
BR is the bit rate set in the receiver and
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 be
careful to use the same division ratio in the receiver and in the transmitter.
5. Power Setting Command
Bit 10 (p16): pin16 function select
Bit
Bit
Bit
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 f
calculated as:
f
0
15
15
15
1
1
1
= 10 * C1 * (C2 + F/4000)
Clock recovery in slow mode:
14
14
14
0
1
0
13
13
13
0
0
1
12
12
1
12
0
0
11
11
f11
0
11
0
[MHz]


p16
BR is the bit rate difference between the transmitter and the receiver. N
10
10
BR / BR < 1 / (29*N
f10
10
1
p16
0
1
d1
9
9
1
f9
9
d0
8
8
0
f8
8
cs
i2
7
7
f7
bit
7
0
)
Function of pin 16
can be
Interrupt input
r6
i1
6
6
VDI output
f6
6
r5
5
i0
5
f5
5
Clock recovery in fast mode:
The constants C1 and C2 are determined by
the selected band as:
g1
r4
4
4
Band [MHz]
f4
4
315
433
868
915
g0
r3
3
3
f3
3
r2
r2
2
2
f2
2
C1
1
1
2
3
r1
r1
1
1
f1
1
C2
31
43
43
30
r0
r0
0
0
f0

0
BR / BR < 3 / (29*N
bit
is the maximal number of
9080h
C623h
POR
POR
A680h
POR
Si4420
bit
)
14