micrf506 Micrel Semiconductor, micrf506 Datasheet - Page 20

• Manufacturer Part Number: micrf506
• Description: 410mhz And 450mhz Ism Band Transceiver
• Manufacturer: Micrel Semiconductor

Bit Synchronizer
A bit synchronizer can be enabled in receive mode
by selecting the synchronous mode (Sync_en=1).
The DataClk pin will output a clock with twice the
frequency of the bit rate (a bit rate of 20 kbit/sec
gives a DataClk of 20 kHz). A received symbol/bit on
DataIXO will be output on rising edge of DataClk.
The micro controller should therefore sample the
symbol/bit on falling edge of DataClk.
The bit synchronizer uses a clock which needs to be
programmed according to the bit rate. The clock
frequency should be 16 times the actual bit rate (a
bit rate of 20 kbit/sec needs a bit synchronizer clock
with frequency of 320 kHz). The clock frequency is
set by the following formula:
f
0000110
0000111
BITSYNC_CLK
Micrel
September 2004
A6..A0
BitRate_clkS1
=
D7
Refclk_K
2
-
BitRate_clkS0
ModclkS2
f
XCO
D6
(7- BITSYNC_clkS )
RefClk_K5
ModclkS1
D5
RefClk_K4
ModclkS0
D4
20
BitSync_clkS2
RefClk_K3
where
Refclk_K is also used to derive the modulator clock
and the bit rate clock.
At the beginning of a received data package, the bit
synchronizer clock frequency is not synchronized to
the bit rate. When these two are maximum offset to
each other, it takes 22 bit/symbols before
synchronization is achieved.
D3
f
frequency (16 times higher than the bit rate)
f
Refclk_K:
between 1 and 63
BitSync_clkS:
values between 0 and 7
BITSYNC_CLK
XCO
:
BitSync_clkS1
RefClk_K2
:
D2
The
Crystal oscillator frequency
6
Bit synchronizer setting,
bit
BitSync_clkS0
bit
RefClk_K1
synchronizer
D1
divider,
[phone]
M9999-092904
MICRF506
BitRate_clkS2
RefClk_K0
values
D0
clock