EM2420 ETC [List of Unclassifed Manufacturers], EM2420 Datasheet - Page 35

• Manufacturer Part Number: EM2420
• Description: 2.4 GHz IEEE 802.15.4 / ZigBee RF Transceiver
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Figure 16. Transmitted Synchronization Header
Length field
The frame length field shown in Figure 15
defines the number of bytes in the MPDU.
Note that the length field does not include
the length field itself. It does however
include
Sequence),
automatically by the EM2420 hardware. It
also includes the MIC if authentication is
used.
The length field is 7 bits and has a
maximum
significant bit in the length field is reserved
[1], and should be set to zero.
The EM2420 hardware uses the length field
both for transmission and reception, so
this field must always be included even if
implementing a proprietary (non 802.15-4)
system.
Bits: 0-2
Frame
Type
Figure 17. Format of the Frame Control Field (FCF) [1]
Frame check sequence
A 2-byte frame check sequence (FCS)
follows the last MAC payload byte as
shown in Figure 15. The FCS is calculated
over the MPDU, i.e. the length field is not
part of the FCS. This field is automatically
Ember Part Number: 120-0049-000C
IEEE 802.15.4
3
Security
Enabled
the
EM24420
value
even
FCS
4
Frame
Pending
of
if
2·(PREAMBLE_LENGTH + 1) zero symbols
0
127.
this
(Frame
0
5
Acknowledge
request
is
The
inserted
Check
0
most
EM2420 Datasheet
SW0 = SYNCWORD[3:0]
SW1 = SYNCWORD[7:4]
SW2 = SYNCWORD[11:8]
SW3 = SYNCWORD[15:12]
Preamble
0
6
Intra
PAN
Synchronisation Header
0
In transmit mode, the length field is used
for underflow detection, as described in
the FIFO access section on page 29.
MAC protocol data unit
The FCF, data sequence number and
address information follows the length field
as shown in Figure 15. Together with the
MAC data payload and Frame Check
Sequence, they form the MAC Protocol
Data Unit (MPDU).
The format of the FCF is shown in Figure
17. Please refer to [1] for details.
There is no hardware support for the data
sequence number, this field must be
inserted and verified by software.
The EM2420 includes hardware address
recognition, as described in the Address
Recognition section on page 39.
generated and verified by hardware when
the MODEMCTRL0.AUTOCRC control bit is
set. It is recommended to always have this
enabled,
purposes. If cleared, CRC generation and
verification
software.
7-9
Reserved
0
if different from 'F', else '0'
if different from 'F', else '0'
if different from 'F', else '0'
if different from 'F', else '0'
SW0
except
0
10-11
Destination
addressing
mode
must
SW1
0
possibly
be
SW2
12-13
Reserved
EM2420
7
SFD
performed
SW3
A
for
Page 35 of 89
14-15
Source
addressing
mode
debug
by