Rainbow Electronics ATmega128RFA1 - Manual (Page 65)

65
8266A-MCU Wireless-12/09
ATmega128RFA1
9.5.1.2.3 Frame Compatibility between IEEE 802.15.4-2003 and IEEE 802.15.4-2006
All unsecured frames according to IEEE 802.15.4-2006 are compatible with unsecured
frames compliant with IEEE 802.15.4-2003 with two exceptions: a coordinator
realignment command frame with the “Channel Page” field present (see IEEE 802.15.4-
2006 7.3.8) and any frame with a MAC Payload field larger than
aMaxMACSafePayloadSize
octets.
Compatibility for secured frames is shown in the following table, which identifies the
security operating modes for IEEE 802.15.4-2006.
Table 9-19. Frame Control Field – Security and Frame Version
Frame Control Field Bit Assignments
Security Enabled
b
3
Frame Version
b
13
b
12
Description
0 00 No security. Frames are compatible between
IEEE 802.15.4-2003 and IEEE 802.15.4-2006.
0 01 No security. Frames are not compatible between
IEEE 802.15.4-2003 and IEEE 802.15.4-2006.
1 00 Secured frame formatted according to
IEEE 802.15.4-2003. This frame type is not
supported in IEEE 802.15.4-2006.
1 01 Secured frame formatted according to
IEEE 802.15.4-2006
9.5.1.2.4 Sequence Number
The one-octet sequence number following the FCF identifies a particular frame, so that
duplicated frame transmissions can be detected. While operating in RX_AACK mode,
the content of this field is copied from the frame to be acknowledged into the
acknowledgment frame.
9.5.1.2.5 Addressing Fields
The addressing fields of the MPDU are used by the radio transceiver for address
matching indication. The destination address (if present) is always first, followed by the
source address (if present). Each address field consists of the Intra PAN-ID and a
device address. If both addresses are present and the “Intra PAN-ID compression”
subfield in the FCF is set to one, the source Intra PAN-ID is omitted.
Note that in addition to these general rules IEEE 802.15.4 further restricts the valid
address combinations for the individual possible MAC frame types. For example the
situation where both addresses are omitted (source addressing mode = 0 and
destination addressing mode = 0) is only allowed for acknowledgment frames. The
address filter in the radio transceiver has been designed to apply to IEEE 802.15.4
compliant frames. It can be configured to handle other frame formats and exceptions.
9.5.1.2.6 Auxiliary Security Header Field
The Auxiliary Security Header specifies information required for security processing and
has a variable length. This field determines how the frame is actually protected (security
level) and which keying material from the MAC security PIB is used (see
IEEE 802.15.4-2006, 7.6.1). This field shall be present only if the Security Enabled