MICRF219 Datasheet, PDF (17/24 Pages) Micrel Semiconductor – 300MHz to 450MHz ASK Receiver with RSSI, Auto-Poll, Bit-Check and Squelch

Micrel
MICRF219
Figure 12. Time-to-Good-Data After Shut Down Cycle,
315MHz at Room Temperature.
Serial Register Programming
Programming the device is accomplished by the use
of pins DO and SCLK. Normally, D0 (Pin 10) is
outputting data and needs to switch to an input pin
made by the start sequence, as shown at Figure 13.
High at the SCLK pin tri-states the DO pin, enabling
the external drive into the DO pin with an initial low
level. The start sequence is completed by taking
SCLK low, then high while DO is low, followed by
taking DO high, then low while SCLK is high. The
serial interface is initialized and ready to receive the
programming data.
SCLK
T6 T7
BIT TIME 0
BIT TIME 1
T1
DO AS
OUTPUT
T2
T3
T4 T5
T8 T9
“19”
“0”
DO INPUT BITS:
D19
D18
BIT TIME 2
“0”
“1”
D17
Figure 13. Serial Interface Start Sequence.
are programmed as needed. It is recommended that
all parallel input pins (SEL0, SEL1, and SQ) be kept
high when using the serial interface. After the
programming bits are finished, a stop sequence (as
shown in Figure 14) is required to end the mode and
reestablish the DO pin as an output again. To do so,
the SCLK pin is kept high while the DO pin changes
from low to high, then low again, followed by the
SCLK pin made low. Timing of the programming bits
are not critical, but should be kept as shown below:
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.
Bits are serially programmed starting with the most
significant bit (MSB = D19) if all bits are being
programmed until the least significant bit (LSB =D0)
For instance, if only the desense bits D0, D1, and D2
are being programmed, then these are the only bits
that need to be programmed with the start sequence
D2, D1, D0, plus the stop sequence. Or, if only the
squelch bit D17 is needed, then the sequence must
be from start sequence, D17 through D0 plus the stop
sequence, making sure the other bits (besides D17)
January 2009
17
M9999-011509
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