1999 Apr 12
63
Philips Semiconductors
Product specification
FLEX
roaming decoder II
PCD5013
8.8.9.3
Calculating how long tasks take
Since the TimeToTaskDisabled discussed in the previous
section limits how much the host can do while the
PCD5013 is battery saving, it is necessary for the host to
know how long it can take the PCD5013 to perform a task.
The formulae below calculate how long the two types of
host initiated tasks take to complete as measured from the
last SPI clock of the packet that initiates the task to the
time the receiver shutdown sequence starts. Note that the
receiver shutdown sequence must start before tasks are
disabled.The following definitions are used:
TotalWarmUpTime:
The sum of the times programmed
for the used warm-up steps plus the time programmed for
the 3200 sps Sync Setting in the receiver control
configuration packets
AST:
The value configured using the timing control packet.
Equation (1) calculates how long it takes to complete a
Noise Detect started by setting the SND bit in the roaming
control packet. This formula assumes that:
the noise detect was performed while in synchronous
mode OR
the noise detect was performed in asynchronous mode
and did not find FLEX
signal OR
the noise detect found FLEX
signal but the DAS bit of
the roaming control packet was set.
Equation (2) calculates how long it will take to complete an
A-word search initiated by setting the SAS bit in the
roaming control packet. This formula assumes that the
A-word search failed to find roaming FLEX
channel.
Equation (3) calculates how long it will take to complete a
Noise Detect/A-word search combination. This can occur
when the noise detect is performed while in asynchronous
mode, the noise detect finds FLEX
signal, and the DAS
bit of the roaming control packet is not set.
(1)
(2)
(3)
TimeToPerformNoiseDetect
TotalWarmUpTime
82 ms
+
≤
TimeToPerformAwordSearch
TotalWarmupTime
AST
47 ms
+
+
≤
TimeToPerformBoth
TotalWarmUpTime
AST
127 ms
+
+
≤