EM2420 ETC [List of Unclassifed Manufacturers], EM2420 Datasheet - Page 32

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

Figure 12. Pin activity examples during receive
Transmit mode
During transmit, the FIFO and FIFOP pins
are still only related to the RXFIFO. The
SFD
transmission of a data frame, as shown in
Figure 13.
The SFD pin goes high when the SFD field
has been completely transmitted. It goes
low again when the complete MPDU (as
defined by the length field) has been
transmitted or if an underflow is detected.
Figure 13. Pin activity example during transmit
General control and status pins
In receive mode, the FIFOP pin can be
used to interrupt the microcontroller when
a threshold has been exceeded or a
Ember Part Number: 120-0049-000C
higher than frame length
Data transmitted
lower than frame length
FIFOP Pin, if threshold
FIFOP Pin, if threshold
Data received over RF
Data received over RF
SFD Pin
over RF
pin
FIFOP Pin
FIFO Pin
FIFO Pin
SFD Pin
SFD Pin
12 symbol periods
is
however
Preamble
Preamble
Automatically generated
preamble and SFD
Preamble
active
SFD Length
SFD Length
during
SFD Length
EM2420 Datasheet
MAC Protocol Data Unit (MPDU) with correct address
See the RF Data Buffering section on
page 37 for more information on TXFIFO
underflow.
As can be seen from comparing Figure 12
and Figure 13, the SFD pin behaves very
similarly during reception and transmission
of a data frame. If the SFD pins of the
transmitter and the receiver are compared
during the transmission of a data frame, a
small delay of approximately 2 µs can be
seen because of bandwidth limitations in
both the transmitter and the receiver.
complete frame has been received. This
pin should then be connected to a
microcontroller interrupt pin.
MAC Protocol Data Unit (MPDU) with wrong address
Data fetched
from TXFIFO
MAC Protocol Data Unit (MPDU)
EM2420
CRC generated
Page 32 of 89
by EM2420