SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
The transmit operation is a foreground-level operation that transmits one packet. The operation is started with the CMD_IEEE_TX command, and uses the command structure given in Table 26-65.
When the radio CPU receives the command, it waits for the start trigger. Any background-level operation keeps running during this wait time. At the start trigger, the radio CPU suspends the receiver and configures the transmitter. It is assumed that the synthesizer is powered and calibrated, so if no background-level operation is running, the TX operation must be preceded with a calibrate synthesizer command. If the frequency synthesizer is not running, the operation ends with an error.
The transmitter transmits the payload found in the buffer pointer to pPayload, which consists of payloadLen bytes. If txOpt.payloadLenMsb is nonzero, this field is multiplied by 256 and added to payloadLen to create (for test purposes) a long frame that is not compliant with IEEE 802.15.4. If txOpt.bIncludePhyHdr is 0, the radio CPU inserts a PHY header automatically, calculated from the payload length. Otherwise, no PHY header is inserted by the radio CPU, so for IEEE 802.15.4 compliance, the first byte in the payload buffer must be the PHY header.
The payload is then transmitted as found in the payload buffer. If txOpt.bIncludeCrc is 0, the radio CPU appends two CRC bytes, calculated according to the IEEE 802.15.4 standard. Otherwise, no CRC is appended, so for IEEE 802.15.4 MAC compliance, the last two bytes in the payload buffer must be the MAC footer. The transmit operation can be ended by one of the immediate commands CMD_ABORT, CMD_STOP, CMD_IEEE_ABORT_FG, and CMD_IEEE_STOP_FG. If CMD_ABORT or CMD_IEEE_ABORT_FG is received, the transmission ends as soon as possible in the middle of the packet. If CMD_STOP or CMD_IEEE_STOP_BG is received while the radio CPU is waiting for the start trigger, the operation ends without any transmission; otherwise, the transmission is finished, but the end status and result differ as explained in the following.
When transmission of the packet starts, the trigger RAT time used for starting the modem is written to the timeStamp field by the radio CPU. This timestamp is delayed by the firmware-defined parameter startToTXRatOffset, compared to the configured start time of the CMD_IEEE_TX command. If the transmitter and receiver have synchronized RAT timers, this timestamp is the same as the timestamp appended to the RX entry element, as in Section 26.7.1, although with estimation uncertainty on the receiver side.
When the operation ends, the end time of the transmitted frame is defined as event 1, and may be used for timing subsequent chained operations.
Table 26-86 lists the causes of a transmit operation end. The status field of the command structure after the command has ended indicates the reason why the operation ended. In all cases, an FG_COMMAND_DONE interrupt is raised. In each case, it is indicated if the result is TRUE, FALSE, or ABORT. This indicates whether to start the next command (if any) in pNextOp, or to return to an IDLE state.
| Condition | Status Code | Result |
|---|---|---|
| Packet transmitted | IEEE_DONE_OK | TRUE |
| Received CMD_STOP or CMD_IEEE_STOP_FG, then finished transmitting if started | IEEE_DONE_STOPPED | FALSE |
| Received CMD_ABORT or CMD_IEEE_ABORT_FG | IEEE_DONE_ABORT | ABORT |
| Observed illegal parameter | IEEE_ERROR_PAR | ABORT |