HP X09 Manuel télécharger pdf (Page 13)

XStream‐PKG‐E™EthernetRFModem–ProductManualv5.x00[2006.02.24]

3. RFModemOperation

3.1. Modes of Operation

An on-board RF module enables the XStream RF Modem to send and receive data over-the-air.

The RF modem operates in five modes.

Figure3‐01. RFModemMod esofOperation

The RF modem can only be in one mode at a time.

3.1.1. Idle Mode

When not receiving or transmitting data, the RF modem is in Idle Mode. The RF modem uses the

same amount of power in Idle Mode as it does in Receive Mode.

The modem shifts into the other modes of operation under the following conditions:

• 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)

After responding to any of the preceding conditions, the modem automatically transitions back

into Idle Mode.

3.1.2. Transmit Mode

When the first byte of serial data is received from the UART in the DI buffer, the modem

attempts to shift to Transmit Mode and initiate an RF connection with other modems. After

transmission is complete, the modem returns to Idle Mode.

RF transmission begins after either of the following criteria is met:

1. RB bytes have been received in the DI buffer and are pending for RF transmission [refer to

RB (Packetization Threshold) command, p32].

The RB parameter may be set to any value between 1 and the RF packet size (PK), inclusive.

When RB = 0, the packetization threshold is ignored.

2. At least one character has been received in the DI buffer (pending for RF transmission) and

RO time has been observed on the UART [refer to RO (Packetization Timeout) command].

The timeout can be disabled by setting RO to zero. In this case, transmission will begin after

RB bytes have been received in the DI buffer.

Note: RF reception must

complete before the

modem is able to enter

into Transmit Mode.

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HP X09 Manuel Page 13