Timer 2 Capture Settings; End-Of-Task Causes - Texas Instruments CC253x User Manual

Link Layer Engine
TXCAP
00
01
10
11
RXCAP
00
01
10
11
When capture is done at the beginning of a packet, the time captured is the time right after the sync word
has been received or transmitted. Setting TXCAP or RXCAP to 11 enables capture at the start of a packet,
but the capture is turned off after a packet has been transmitted or fully received in a task, so it is the start
of the first packet in the task that is captured. The MCU should normally only read the captured value after
a task is done; otherwise, the captured value may be overwritten with a new value. The user must take
into account that a timer value may be captured on a received packet that does not match the address or
that has a length which is not permitted, and that is thus not reported. It is possible to turn on capture for
both received and transmitted packets in the same task. If so, it is up to the user to determine if the
captured value was from a received or transmitted packet.
When a task is finished, the LLE writes an end-of-task cause in PRF_ENDCAUSE, frees the semaphores,
raises a TASKDONE interrupt, and halts its operation. The possible values of PRF_ENDCAUSE are listed in
Table 25-14.
If PRF_CHAN.SYNTH_ON is 1, the synthesizer is not turned off after the task ends. This can be used to
start a new task immediately on the same channel and get faster start of RX or TX. To do so, the next
task should be started with PRF_CHAN.FREQ set to 127. Note that the synthesizer should not be allowed
to run for a long time after a task has ended, as this causes excessive power consumption. The
synthesizer can be stopped by sending a CMD_SHUTDOWN command.
Number
Normal task ending
0
1
2
3
4
5
6
MCU interface error
255
254
253
252
251
250
304 CC2541 Proprietary Mode Radio
Table 25-13. Timer 2 Capture Settings
Capture of transmitted packets off
Capture the start (after the sync word) of every transmitted packet
Capture the end of every transmitted packet
Capture the start of the first transmitted packet, that is, capture of transmitted packets is turned
off after a packet has been transmitted.
Capture of received packets off
Capture the start (after the sync word) of every received packet
Capture the end of every received packet
Capture the start of the first received packet, that is, capture of received packets is turned off
after a packet has been fully received.
Table 25-14. End-of-Task Causes
Name
TASK_ENDOK
TASK_RXTIMEOUT
TASK_NOSYNC
TASK_NOCC
TASK_MAXRT
TASK_STOP
TASK_ABORT
TASKERR_INTERNAL
TASKERR_CMD
TASKERR_SEM
TASKERR_PAR
TASKERR_TXFIFO
TASKERR_RXFIFO
Copyright © 2009–2014, Texas Instruments Incorporated
Description
Description
Description
Task ended normally
Timer 2 event 2 or CMD_STOP observed while waiting for RX
sync
Sync was not obtained in the specified time
TX_ON_CC ended because channel was not clear
Task ended because maximum number of retransmissions was
reached
Task ended after transmission or reception by Timer 2 event 2
or CMD_STOP while transmitting or receiving or with ACK or
retransmission in progress
Task aborted by command
Internal program error
Unknown command
Unable to obtain semaphore
Unpermitted parameter
TX FIFO without available data when not permitted
Overfull RX FIFO in TX task
SWRU191F – April 2009 – Revised April 2014
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