CC2420 Datasheet, PDF (37/87 Pages) List of Unclassifed Manufacturers – 2.4 GHz IEEE 802.15.4 / ZigBee-ready RF Transceiver

SmartRF ^® CC2420
Data
input
(LSB
first)
r0 r1 r2 r3
r4 r5 r6 r7 r8 r9 r10
r11 r12 r13 r14 r15
Figure 19. CC2420 Frame Check Sequence (FCS) hardware implementation [1]
Length byte
Data in RXFIFO
n
MPDU₁
MPDU₂
MPDU
MPDU_n-2
RSSI
(signed)
CRC / Corr
Bit number 7 6 5 4 3 2 1 0
CRC
OK
Correlation value (unsigned)
Figure 20. Data in RXFIFO when MDMCTRL0.AUTOCRC is set
RF Data Buffering
CC2420 can be configured for different
transmit and receive modes, as set in the
MDMCTRL1.TX_MODE
and
MDMCTRL1.RX_MODE control bits.
Buffered mode (mode 0) will be used for
normal operation of CC2420, while other
modes are available for test purposes.
section on page 42 for an illustration of
how the transmit command strobes affect
the state of CC2420. The STXONCCA strobe
is ignored if the channel is busy. See the
Buffered transmit mode
In buffered transmit mode (TX_MODE 0),
the 128 byte TXFIFO, located in CC2420
RAM, is used to buffer data before
transmission. A preamble sequence
(defined in the Frame Format section
below) is automatically inserted before the
length field during transmission. The
length field must always be the first byte
written to the transmit buffer for all frames.
Writing one or multiple bytes to the
TXFIFO is described in the FIFO access
section on page 29. Reading data from the
TXFIFO is possible with RAM access, but
this does not remove the byte from the
FIFO.
Transmission is enabled by issuing a
STXON or STXONCCA command strobe.
See the Radio control state machine
Chipcon AS SmartRF^® CC2420 Preliminary Datasheet (rev 1.2), 2004-06-09
Page 37 of 87