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PAGE 14
Modes of Operation
WCM802 / WCM900 OEM RF Modules operate in five modes.
Figure 2.4. WCM802 / WCM900 Modes of Operation
The module can only be in one mode at a time.
Idle Mode
When not receiving or transmitting data, the module is in Idle Mode. The module uses the same
amount of power in Idle Mode as it does in Receive Mode.
The module shifts into the other modes of operation under the following conditions:
After responding to any of the preceding conditions, the module automatically transitions back
into Idle Mode.
Transmit Mode
When the first byte of serial data is received from the UART in the DI buffer, the module attempts
to shift to Transmit Mode and initiate an RF connection with other modules.
Figure 2.5. Transmission of Data
Once in Transmit Mode, the
module initializes a
communications channel. Channel
initialization is the process of
sending an RF initializer that
synchronizes receiving modules
with the transmitting module.
When streaming multiple RF
packets, the RF Initializer is only
sent in front of the first packet.
During channel initialization,
incoming serial data accumulates
in the DI buffer.
After the channel is initialized, data
in the DI buffer is grouped into packets (up to 64 bytes in each packet) and is transmitted. The
module continues to transmit data packets until the DI buffer is empty. Once transmission is
finished, the module returns to Idle Mode. This progression is shown in Figure 2.5.
As the transmitting module nears the end of the transmission, it inspects the DI buffer to see if
more data exists to be transmitted. This could be the case if more bytes arrived from the host
after the transmission began. If more data is pending, the transmitting module assembles a
subsequent packet for transmission.
20 JUN 2005
• Serial data is received in the DI Buffer (Transmit Mode)
• Valid RF data is received through the antenna (Receive Mode)
• Command Mode Sequence is issued (Command Mode)
• Sleep Mode condition is met (Sleep Mode)
WCM802/900
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