Texas Instruments SimpleLink CC2620 Technical Reference Manual page 1590

Proprietary Radio
When formatConf.whitenMode is 5 or 7, the radio is configured to produce the 32-bit CRC and whitening
defined in IEEE 802.15.4g. When formatConf.whitenMode is 6 or 7, the radio also processes the headers
in both receive and transmit as follows:
• If bit 15 of the header (counted from the LSB) is 1, the frame is assumed to consist of only a header,
with no payload or CRC.
• If bit 12 of the header (counted from the LSB) is 1, the 16-bit CRC defined in IEEE 802.15.4g is
assumed instead of the 32-bit CRC. For TX, 2 is added to the length offset to account for this,
assuming the CRC is included in the received frame length.
• For mode 7: If bit 11 of the header (counted from the LSB) is 1, whitening is enabled; otherwise it is
disabled.
NOTE: The IEEE 802.15.4g PHY header must be presented MSB first to the RF Core. In IEEE
802.15.4g specification, the payload part is LSb first, however the payload length info in
physical layer header (PHR) is MSb first. This means that the payload needs to be flipped in
the CM-3. This can be achieved with the CM3 assembly instruction RBIT
The following example shows how to send a CRC-32 IEEE 802.15.4g frame with whitening enabled using
the automatic headers processing feature (formatConf.whitenMode = 7).
/*
* Prepare the .15.4g PHY header
* MS=0, Length MSBits=0, DW and CRC settings read from 15.4g header (PHDR) by
RF core.
* Total length = transmit_len (payload) + CRC length
*
* The Radio will flip the bits around, so tx_buf[0] must have the
* length LSBs (PHR[15:8] and tx_buf[1] will have PHR[7:0]
*/
/* Length in .15.4g PHY HDR includes the CRC but not the HDR itself */
uint16_t total_length;
total_length = transmit_len + CRC_LEN; /* CRC_LEN is 2 for CRC-
16 and 4 for CRC-32 */
tx_buf[0] = total_length & 0xFF;
tx_buf[1] = (total_length >> 8) + 0x08 + 0x0; /* Whitening and CRC-32 bits */
tx_buf[2] = data;
NOTE: If IEEE 802.15.4g mode is configured (CMD_PROP_RADIO_SETUP with
formatConf.whitenMode = 4, 5, 6, or 7), packets transmitted using unlimited length (pktLen =
0, pPkt pointing to a Tx queue) will not get the correct CRC for payloads shorter than 4
bytes, if the CRC for the packet is 4 bytes long. The reason is that the payload in this case
will be padded with 4 zero bytes before CRC is calculated. This padding (1-4 bytes) only
occur for packets with less than 4 bytes payload, hence application need to ensure payload
is longer than 4 bytes.
An MCE patch is necessary to support FEC, Mode Switch, or other advanced features of IEEE 802.15.4g
PHY.
23.7.5.3 Transmitter Commands
There are two commands for sending packets, CMD_PROP_TX and CMD_PROP_TX_ADV. The latter
gives more flexibility in how the packet can be formed. Details of this are described in
and Section 23.7.5.3.2, respectively.
Both commands require the radio is set up in a compatible mode (such as proprietary mode), and that the
synthesizer is programmed using CMD_FS.
1590
Radio
Copyright © 2015, Texas Instruments Incorporated
Section 23.7.5.3.1
SWCU117C – February 2015 – Revised September 2015
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