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Link Layer Engine
Table 25-18. End-of-Receive Tasks (continued)
Condition
End-of-Task Cause
Comment
Did not get sync in the time specified by
TASK_NOSYNC
PRF_SEARCH_TIME
Received command for starting new task or
If transmitter was running or receiver was
CMD_SHUTDOWN or observed Timer 2 event 2 with
running and had obtained sync, an
TASK_ABORT
PRF_TASK_CONF.STOP_CONF
= 10
RXTXABO
interrupt is also raised.
LLEERR
interrupt is also raised. If
transmitter was running or receiver was
Received unknown command
TASKERR_CMD
running and had obtained sync, an
RXTXABO
interrupt is also raised.
Task ends without any radio operation.
Semaphore is not free when expected
TASKERR_SEM
LLEERR
interrupt is also raised.
Unpermitted value of RAM register
TASKERR_PAR
LLEERR
interrupt is also raised.
For
PRF_TASK_CONF.MODE
= 00:
TASKERR_PAR
LLEERR
interrupt is also raised.
PRF_ADDR_ENTRYn.RXLENGTH
corresponding
to the received address is smaller than address length
For auto mode:
TASKERR_PAR
PRF_ADDR_ENTRYn.ACKLENGTGHm
for the
LLEERR
interrupt is also raised.
ACK payload to be transmitted exceeded 32
25.9.2.4 Transmit Task
When a CMD_TX command is received, the LLE configures the radio on the channel given by
PRF_CHAN.FREQ
and starts transmitting the packet from the Tx FIFO.
If the Tx FIFO has no available data, the task ends with TASKERR_TXFIFO as the end cause. Otherwise,
the number of bytes given by the length byte in the Tx FIFO is read from the Tx FIFO and transmitted or
otherwise handled as described in following sections. No check of data availability is done after the length
byte is read, so if the FIFO contains fewer bytes than indicated in the length field, a Tx FIFO underflow
interrupt is raised by the FIFO hardware.
25.9.2.4.1 Basic Mode
This section describes the transmit operation if
PRF_TASK_CONF.MODE
is 00 or 01.
If
PRF_TASK_CONF.MODE
is 01, the length field is calculated from the length field in the FIFO and
transmitted. It is up to the MCU to ensure that the calculated length field does not exceed 255. If
PRF_TASK_CONF.MODE
is 00, no length field is transmitted.
If an address is configured, it is found based on the setting in
PRF_FIFO_CONF.TX_ADDR_CONF
. It can
be set to take the address from
PRF_ADDR_ENTRY0
, to read it from the Tx FIFO (which for the transmitter
is equivalent to not having an address configured), or to read an index n from the config byte in the FIFO
and read the address from
PRF_ADDR_ENTRYn.ADDRESS
. The values of
ENA0
and
ENA1
in
PRF_ADDR_ENTRYn.CONF
are ignored for the transmitter; the primary sync word is always transmitted.
The payload (if any) is transmitted as given in the FIFO.
If configured, a CRC with the number of bytes given by
PRF_CRC_LEN
is transmitted at the end.
When a packet has been transmitted, the LLE sends a deallocate Tx FIFO command if
PRF_ADDR_ENTRYn.REUSE
is 0. Otherwise, the MCU must issue either a deallocate Tx FIFO (to send a
new packet) or a retry Tx FIFO (to reuse) before sending again. The
PRF_N_TX
counter is incremented. A
TXDONE
interrupt to the MCU is raised. The next action is as given in
25.9.2.4.2 Auto Mode
This section describes the transmit operation if
PRF_TASK_CONF.MODE
is 10 or 11.
323
SWRU191C
–
April 2009
–
Revised January 2012
CC2541 Proprietary Mode Radio
Copyright
©
2009
–
2012, Texas Instruments Incorporated