SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
The receive radio operation is a background-level operation, started with the CMD_IEEE_RX command and using the command structure given in Table 26-62.
At the start of an RX operation, the radio CPU waits for the start trigger, then programs the frequency based on the channel parameter. If channel is 0xFF, the operation keeps running on an already configured channel. This requires that the operation follows another receive operation or a synthesizer programming operation. If the frequency synthesizer is not running, the operation ends with an error. After programming the frequency, the radio CPU configures the receiver to receive IEEE 802.15.4 packets.
When the demodulator obtains sync on a frame, the PHY header is read first. The 7 LSBs of this byte give the frame length. The further treatment depends on the setting of frameFiltOpt. If frameFiltOpt.frameFiltEn is 1, further frame filtering is done as explained below. If it is 0, no frame filtering is done.
The number of bytes given by the received PHY header are received and stored in the receive queue given by pRxQ. As explained in Section 26.7.1, the format depends on rxConfig. The last two bytes of the PHY payload are the FCS, or CRC, for the packet. These bytes are checked according to the FCS specification, and the further treatment depends on the CRC result.
If there is a CRC error and rxConfig.bAutoFlushCrc is 1, the packet is discarded from the RX buffer. If there is no available RX buffer with enough available space to hold the received packet, the received data is discarded. If frameFiltOpt.frameFiltStop is 1, the reception stops, otherwise the packet is received so that the CRC can be checked.