
FLEX
TM
ROAMING DECODER II
S5T8701
64
Calculating How Long Tasks Take
Since the Time To Task Disabled discussed in the previous section limits how much the host can do while the
S5T8701 is battery saving, it is necessary for the host to know how long it can take the S5T8701 to perform a
task.
The formulas 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 formula calculates how long it will take to complete a Noise Detect started by setting the
SND
bit in
the roaming control packet. This formula assumes that (1) the noise detect was performed while in synchronous
mode or (2) the noise detect was performed in asynchronous mode and did not find FLEX signal or (3) the noise
detect found FLEX signal but the
DAS
bit of the roaming control packet was set.
Time To Perform Noise Detect
—
Total Warm Up Time + 82ms
Where,
Total Warm Up Time
: The sum of the times programmed for the used warm up steps plus the time
programmed for the 3200sps Sync Setting in the receiver control configuration
packets.
The following formula 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.
Time To Perform A word Search
—
Total Warm Up Time + AST + 47ms
Where,
Total Warm Up Time: The sum of the times programmed for the used warm up steps plus the time programmed
for the 3200sps Sync Setting in the receiver control configuration packets.
AST:
The value configured using the timing control packet.
The following formula 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.
Time To Perform Both
—
Total Warm Up Time + AST + 127ms
Where,
Total Warm Up Time: The sum of the times programmed for the used warm up steps plus the time programmed
for the 3200sps Sync Setting in the receiver control configuration packets.
AST:
The value configured using the timing control packet.