MICRF221 查看數據表（PDF） - Micrel
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MICRF221 Datasheet PDF : 26 Pages
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Micrel Inc.
Operation
Trigger pulses are generated from internal D0 edges
and compare with programmable window generated
from the reference clock frequency. If time between
data edges falls within the window data pulse width is
bad. Detected stable bits are counted. Wakeup will
occur allowing data to output if sufficient data bits are
detected. Two bad pulses or lack of pulse cause
device to go to sleep for sleep timer duration.
Squelch action
During normal operation, if 4 or less out of 8 bit pulses
are good squelch output is actived. If good bit count
increases to 7 or more in any 8 sequential bits
squelch output is set low allowing data to output at DO
pin.
Serial Interface
Control Register Individual Truth Tables:
D0
D1
D2 MODE: Desense
0
X
X
No Desense - default
1
0
0
7dB Desense
1
1
0
19dB Desense
1
0
1
32dB Desense
1
1
1
42dB Desense
D3
D4 MODE:
Demod Bandwidth (at 915MHz)
0
0
1625Hz
1
0
3250Hz
0
1
6500Hz
1
1
13000Hz - default
D5
D6 MODE
1
0
Slice Level 30%
0
1
Slice Level 40%
1
1
Slice Level 50% - default
0
0
Slice Level 60%
D7
D8 MODE: Bit Check Setting
0
0
Bitcheck 0 bits - default
1
0
Bitcheck 2 bits
0
1
Bitcheck 4 bits
1
1
Bitcheck 8 bits
MICRF221
D9
D10 D11 MODE:
Bitcheck Window Times
(915MHz)
0
0
0
67us, 136us, 270us, 541us
1
0
0
64us, 126us, 252us, 505us
0
1
0
59us, 118us, 234us, 469us
1
1
0
54us, 108us, 216us, 434us
0
0
1
49us, 100us, 198us, 397us
1
0
1
45us, 90us, 180us, 361us
0
1
1
41us, 82us, 163us, 325us
1
1
1
36us, 72us, 144us, 289us
D12
D13
D14 MODE:
Sleep Time
0
0
0
10ms
1
0
0
20ms
0
1
0
40ms
1
1
0
80ms
0
0
1
160ms
1
0
1
320ms
0
1
1
640ms
1
1
1
1280ms
D15 MODE: Auto Poll
0
Awake – does not poll - default
1
Auto-polls with Sleep periods
D16 MODE: Demod BW Select
0
Normal Demod BW’s - default
1
Fast Demod BW’s
D17 MODE: Squelch Enable
0
Squelch circuit off - default
1
Squelch circuit active
D18 MODE
0
Sleep polling watchdog active - default
Watchdog time for D3, D4, BW setting:
11 01 10
00
5ms 5ms 10ms 20ms
1
Sleep polling watchdog disabled - unlimited
poll period
D19 MODE
0
RSSI offset 0mV - default
1
RSSI offset +200mV
October 2008
11
M9999-100108
(408) 955-1690
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