SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
26.5.3.1 Receive Buffers
A frame being received is stored in the receive buffer. First, a length byte or word is stored, if configured in the RX entry, by config.lenSz, and calculated from the length received over the air and the configuration of appended status information.
The format of the entry elements in the receive queue pointed to by pRxQ is given by the configuration rxConfig defined in Section 26.6.1.4.
Following the length field, the received PHY header byte is stored if rxConfig.bIncludePhyHdr is 1. If a length field is present, this byte is redundant except for the reserved bit. The received MAC header and MAC payload is stored as received over the air. The MAC footer containing the 16-bit frame check sequence is stored if rxConfig.bIncludeCrc is 1.
If rxConfig.bAppendRssi is 1, a byte indicating the received RSSI value is appended. If rxConfig.bAppendCorrCrc is 1, a status byte of the type defined in Table 26-79, is appended. If rxConfig.bAppendSrcInd is 1, a byte giving the index of the first source matching entry that matches the header of the received packet is appended, or 0xFF if no match. If rxConfig.bAppendTimeStamp is 1, a timestamp indicating the start of the frame is appended. This timestamp is a four-byte number from the radio timer. Though the timestamp is multibyte, no word-address alignment is made, so the timestamp must be written and read bytewise. The timestamp is captured when SFD is found, but adjusted to reflect the start of the frame (assuming 8 preamble bytes as per the standard), defined so that it corresponds to the time of the start trigger used on the transmit side. The adjustment is defined in the syncTimeAdjust firmware-defined parameter, and may be overridden.
Figure 26-6 shows the format of an entry element in the RX queues.
Figure 26-6 RX Queue Entry Element (Stapled Fields are Optional)