11-331
RF3000
Rev A4 031216
RF3000 Method of Operation
The transmitter power enable (TX PE) input enables the transmitter process. (Note: Transmit has priority over receive.)
When TX PE is high, the LNA GS signal will be driven low. The TX RDY output indicates the readiness of the RF3000 to
receive data for transmit. Transmitted data is passed into the RF3000 through the TXDATA input and clocked by the
DATA CLK output. The receiver power enable (RX PE) input enables the receiver, and the receive data ready (RX RDY)
signal indicates that received data is upcoming. The RF3000 generates the received data clocks, and outputs the
received data, through the RX DATA output. The receiver port also provides a clear channel assessment (CCA) to the
MAC.
The table below summarizes the operation of the chip. The user should note that RX PE must be High to perform CCA.
IEEE802.11b Transmit Modes
IEEE802.11b DSSS Transmit Modes
The RF3000 supports PSK and CCK DSSS modes defined in IEEE802.11b specification. The RF3000 also supports the
optional short preamble and header format as defined in IEEE802.11b.
The following section describes IEEE802.11b DSSS data transmission. The user must first prepare the applicable con-
trol port registers to determine the mode of operation and the transmission length. The mode of operation must be writ-
ten into Register 1, followed by setting the transmission length (in microseconds). The length is to be written into
Registers 17 (bit 0 only), 18 and 19. Mode byte values for IEEE802.11b modes are summarized below
.
Once the control port values are written, the RF3000 is ready to transmit data. Optionally, the TX length value can be
written during the 128
µS of preamble. When the user is ready to transmit, TX PE is driven High. This signals the RF3000
to assemble and transmit the 802.11 preamble and header, as described below.
The preamble and header for 1Mbps mode is always transmitted as 1Mbps BPSK. However for 2Mbps, 5.5Mbps and
11Mbps modes, IEEE802.11b allows a short preamble, which has the preamble, transmitted as 1Mbps BPSK and the
header transmitted as 2Mbps QPSK. The usage of the optional short preamble is selected when the transmission mode
is written to the control port.
TX PE
RX PE
Operation
0
0
Standby mode.
0
1
RX is powered up. CCA circuity is active.
1
0
TX is powered up. Begin TX. CCA is inactive.
1
1
RESERVED
IEEE802.11 DSSS Mode
Mode Byte Value
1Mbps DBPSK
0x0016
2Mbps DQPSK Long preamble
0x2016
2Mbps DQPSK Short preamble
0x3016
5.5Mbps CCK Long preamble
0x4016
5.5Mbps CCK Short preamble
0x5016
11Mbps CCK Long preamble
0x6016
11Mbps CCK Short preamble
0x7016
Preamble
Header
Data
128 1’s
SFD
(16-bits)
Service
(8-bits)
Signal
(8-bits)
Length
(16-bits)
CRC
(16-bits)
Data
(x-bits)
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