si4430 Silicon Laboratories, si4430 Datasheet - Page 102

• Manufacturer Part Number: si4430
• Description: Si4430 Ism Transceiver
• Manufacturer: Silicon Laboratories

Register 20h. Clock Recovery Oversampling Rate
Si4430
Reset value = 01100100
The oversampling rate can be calculated as rxosr = 500 kHz/(2
dwn3_bypass values found at Address: 1Ch – IF Filter Bandwidth register together with the receive data rate (Rb)
are the parameters needed to calculate rxosr:
The Rb unit used in this equation is in kbps. The enmanch is the Manchester Coding parameter (see Reg. 70h,
enmach is 1 when Manchester coding is enabled, enmanch is 0 when disabled). The number found in the equation
should be rounded to an integer. The integer can be translated to a hexadecimal.
For optimal modem performance it is recommended to set the rxosr to at least 8. A higher rxosr can be obtained by
choosing a lower value for ndec_exp or enable dwn3_bypass. A correction in filset might be needed to correct the
channel select bandwidth to the desired value. Note that when ndec_exp or dwn3_bypass are changed the related
parameters (rxosr, ncoff and crgain) need to be updated.
102
Name
Type
Bit
7:0
Bit
rxosr[7:0]
Name
D7
Oversampling Rate.
3 LSBs are the fraction, default = 0110 0100 = 12.5 clock cycles per data bit
D6
rxosr
D5

2
500
ndec
Preliminary Rev. 0.4
_

exp

1
D4

3


2
rxosr[7:0]
Rb

R/W
dwn

1 (
Function
3

_
D3
enmanch
bypass
ndec_exp

)
x RX_DR). The ndec_exp and the
D2
D1
D0