CC2430 Datasheet, PDF (176/234 Pages) Texas Instruments – A True System-on-Chip solution for 2.4 GHz IEEE 802.15.4 / ZigBee-TM

CC2430
Data
input
(LSB
first)
r0 r1 r2 r3
r4 r5 r6 r7 r8 r9 r10
r11 r12 r13 r14 r15
Figure 48: CC2430 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 49: Data in RXFIFO when MDMCTRL0L.AUTOCRC is set
14.17 RF Data Buffering
section 14.25 on page 182 for details on
CCA.
CC2430 can be configured for different
transmit and receive modes, as set in the
MDMCTRL1L.TX_MODE
and
MDMCTRL1L.RX_MODE control bits.
Buffered mode (mode 0) will be used for
normal operation of CC2430, while other
modes are available for test purposes.
14.17.1 Buffered transmit mode
In buffered transmit mode (TX_MODE 0),
the 128 byte TXFIFO, located in CC2430
RAM, is used to buffer data before
transmission. A synchronization header 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 169. A DMA transfer can
be configured to write transmit data to the
TXFIFO.
Transmission is enabled by issuing a
STXON or STXONCCA command strobe.
See the Radio control state machine
section on page 179 for an illustration of
how the transmit command strobes affect
the state of CC2430. The STXONCCA strobe
is ignored if the channel is busy. See
The preamble sequence is started 12
symbol periods after the transmit
command strobe. After the programmable
start of frame delimiter has been
transmitted, data is fetched from the
TXFIFO.
The TXFIFO can only contain one data
frame at a given time.
After complete transmission of a data
frame, the TXFIFO is automatically refilled
with the last transmitted frame. Issuing a
new STXON or STXONCCA command
strobe will then cause CC2430 to retransmit
the last frame.
Writing to the TXFIFO after a frame has
been transmitted will cause the TXFIFO to
be automatically flushed before the new
byte is written. The only exception is if a
TXFIFO underflow has occurred, when a
SFLUSHTX command strobe is required.
14.17.2 Buffered receive mode
In buffered receive mode (RX_MODE 0),
the 128 byte RXFIFO, located in CC2430
RAM, is used to buffer data received by
the demodulator. Accessing data in the
RXFIFO is described in the FIFO access
section on page 169.
CC2430 PRELIMINARY Data Sheet (rev. 1.03) SWRS036A
Page 176 of 232