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Page 55

RF96/97/98

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WIRELESS & SENSING

PRELIMINARY

DATASHEET

4.2.7.3. Automatic Restart when Packet Collision is Detected

In receive mode the RF96/97/98 is able to detect packet collision and restart the receiver. Collisions are detected by a

sudden rise in received signal strength, detected by the RSSI. This functionality can be useful in network configurations

where many asynchronous slaves attempt periodic communication with a single a master node.

The collision detector is enabled by setting bit RestartRxOnCollision to 1.

The decision to restart the receiver is based on the detection of RSSI change. The sensitivity of the system can be adjusted

in 1 dB steps by using register RssiCollisionThreshold in RegRxConfig.

4.2.8. Top Level Sequencer

Depending on the application, it is desirable to be able to change the mode of the circuit according to a predefined

sequence without access to the serial interface. In order to define different sequences or scenarios, a user-programmable

state machine, called Top Level Sequencer (Sequencer in short), can automatically control the chip modes.

NOTE THAT THIS FUNCTIONALITY IS ONLY AVAILABLE IN FSK/OOK MODE.

The Sequencer is activated by setting the SequencerStart bit in RegSeqConfig1 to 1 in Sleep or Standby mode (called

initial mode).

It is also possible to force the Sequencer off by setting the Stop bit in RegSeqConfig1 to 1 at any time.

Note

SequencerStart and Stop bit must never be set at the same time.

4.2.8.1. Sequencer States

As shown in the table below, with the aid of a pair of interrupt timers (T1 and T2), the sequencer can take control of the chip

operation in all modes.

Table 70 Sequencer States

Sequencer

State

Description

SequencerOff State

The Sequencer is not activated. Sending a SequencerStart command will launch it.

When coming from LowPowerSelection state, the Sequencer will be Off, whilst the chip will

return to its initial mode (either Sleep or Standby mode).

Idle State

The chip is in low-power mode, either Standby or Sleep, as defined by IdleMode in

RegSeqConfig1

. The Sequencer waits only for the T1 interrupt.

Transmit State

The transmitter in on.

Receive State

The receiver in on.

PacketReceived

The receiver is on and a packet has been received. It is stored in the FIFO.

LowPowerSelection

Selects low power state (SequencerOff or Idle State)

RxTimeout

Defines the action to be taken on a RxTimeout interrupt.

RxTimeout interrupt can be a TimeoutRxRssi, TimeoutRxPreamble or TimeoutSignalSync

interrupt.

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