SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
The CMD_PROP_TX_ADV command transmits a packet with the format from Figure 26-10. As a special case, the user can set up packets as in Figure 26-9. The radio must be set up in a compatible mode (such as proprietary mode) and the synthesizer programmed using CMD_FS. The parameters are as given in Table 26-173.
The packet transmission starts at the given start trigger, with a fixed delay. Alternatively, if startConf.bExtTXTrig is 1, the packet transmission starts on an external trigger to the RF core. The trigger is identified as one of the inputs to the radio timer, and can be configured as rising edge, falling edge, or both edges through the startConf parameter. The system must ensure that this trigger comes after the start trigger, otherwise it is lost. The minimum delay after the start trigger is implementation-dependent and subject to characterization.
The modem first transmits the preamble and sync word as configured. If preTrigger is not TRIG_NOW, the configured preamble is repeated until that trigger (seen in combination with preTime) is observed. After the trigger is observed, the configured preamble under transmission finishes before the sync word transmission starts. If preTrigger is TRIG_NOW, the preamble is sent once, followed by the sync word. The sync word to transmit is given in the syncWord field, in the LSBs if less than 32 bits are used, and is transmitted in the bit order programmed in the radio.
If numHdrBits is greater than 0, a header of numHdrBits is sent next. The header may contain a length field or an address. If so, these fields must be inserted correctly in the packet buffer. The header to be transmitted is the first bytes of the buffer pointed to by pPkt. If numHdrBits does not divide by 8, the MSBs of the last byte of the header are ignored.
The header is transmitted as one field in the bit ordering programmed in the radio. If the header has more than 8 bits, it is always read from the transmit buffer in little-endian byte order. If the radio is configured to transmit the MSB first, the last header byte from the TX buffer is transmitted first.
After the header, the remaining bytes in the buffer pointed to by pPkt are transmitted. The payload is transmitted byte by byte, so after the header, no swapping of bytes occurs regardless of bit ordering over the air. The total number of bytes (including the header) in this buffer is given by pktLen. If this length is too small to fit the header, the operation ends with PROP_ERROR_PAR as status. If an address field after the header as shown in Figure 26-10 is needed, it must be sent as the first payload byte.
If pktLen is 0, unlimited length is used. In this case, pPkt points to a transmit queue instead of a buffer, see Section 26.5.3.2.
If pktConf.bUseCrc is 1, a CRC is calculated and transmitted at the end. The number of CRC bits, polynomial, and initialization are as configured in the radio. If pktConf.bCrcIncSw is 1, the transmitted sync word is included in the data set over which the CRC is calculated. If pktConf.bCrcIncHdr is 1, the transmitted header is included in the data set over which the CRC is calculated. The payload is always used for calculating the CRC.
If whitening is enabled, the optional header is subject to whitening if pktConf.bCrcIncHdr is 1. The entire payload and the CRC are always subject to whitening when enabled. The whitening is done after the data is used for CRC calculation.