CC2420 Chipcon AS, CC2420 Datasheet - Page 30

• Manufacturer Part Number: CC2420
• Description: 2.4 GHz RF Transceiver for IEEE 802.15.4 and ZigBee
• Manufacturer: Chipcon AS

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.
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
complete frame has been received. This
Chipcon AS SmartRF ® CC2420 Preliminary Datasheet (rev 1.0), 2003-11-17
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
Figure 12. Pin activity examples during receive
Figure 13. Pin activity example during transmit
Automatically generated
preamble and SFD
Preamble
active
SFD Length
SFD Length
during
SFD Length
SmartRF
MAC Protocol Data Unit (MPDU) with correct address
See the RF Data Buffering section on
page 34 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.
pin should then be connected to a
microcontroller interrupt pin.
In receive mode, the FIFO pin can be
used to detect if there is data at all in the
receive FIFO.
MAC Protocol Data Unit (MPDU) with wrong address
Data fetched
from TXFIFO
MAC Protocol Data Unit (MPDU)
®
CC2420
CRC generated
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by
CC2420