MICRF221 Datasheet, PDF (18/26 Pages) Micrel Semiconductor – 3.3V, QwikRadio 850 MHz to 950 MHz Receiver

Micrel Inc.
T1 < 0.1 us, Time from SCLK to convert DO to input
pin
T6 > 0.1 us, SCLK high time
T7 > 0.1 us, SCLK low time
T2, T3, T4, T5, T8, T9, T10 > 0.1 us
BIT TIME 18
BIT TIME 19
SCLK
T10
“1”
“0”
“1”
DO
D1
DO
DO PIN AS OUTPUT
Figure 14. Serial Interface Stop Sequence
Serial Interface Examples
All bits (D19 through D0) low (channel 1 is the DO pin,
and Channel 2 is the SCLK pin), see Figure 15.
Figure 15. All bits 0s.
All bits (D19 through D0) High, Figure 16.
Figure 16 All bits 1s.
Only bits 19 and 18 High, Figure 17.
MICRF221
Figure 17 D19 = D18 = 1.
Autopoll example, Figure 18.
D0 = D1 = D2 = 0, no desense
D3 = D4 = 0, demodulator bandwidth = 1712 hertz, 1
kHz baud rate, pulse = 500 usec, required
demodulator bandwidth is 0.65/500usec = 1300 hertz
D5 = D6 = 1, Slice level = 50%
D7 = 0, D8 = 1, bit check = 4 bits. This is the time the
device is ON checking for four consecutive valid
windows.
D9 = D10 = 1, D11 = 0, data rate is 1 kHz, (500 usec
pulses), window set to 433 usec (< 500 usec)
D12 = D13 = 0, D14 = 1, sleep timer set to 160 msec,
that is, 4 bit is ON and 160 msec is OFF.
D15 = 1, device is placed in autopoll
D16 = 0, normal demodulator bandwidth
D17 = 0, squelch is OFF
D18 = 1, watchdog timer is OFF
D19 = 0, no RSSI offset
From MSB to LSB, see Table 7:
D19 D18 D17 D16 D15 D14 D13 D12
01001100
D11 D10 D9 D8 D7 D6 D5
0111011
D4 D3 D2 D1 D0
00000
Table 7. Autopoll example bit sequence
October 2008
18
M9999-100108
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