RF96 datasheet(37/121 Pages) HOPE

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Page 37

RF96/97/98

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WIRELESS & SENSING

PRELIMINARY

DATASHEET

 Each time the RxDone interrupt is received, latch the RegFifoRxByteAddr[7:0] register content in a variable , this

variable will be called start_address. The RegFifoRxByteAddr[7:0] register of the RF96/97/98 gives in real time the

address of the last byte written in the data buffer + 1 (or the address at which the next byte will be written) by the

receive LoRa modem . So by doing this , we make sure that the variable start_address always contains the start

address of the next packet.

 Upon reception of the interrupt ValidHeader, start polling the RegFifoRxByteAddr[7:0] register until it begins to

increment. The speed at which this register will increment depends on the Spreading factor, the error correction code

and the modulation bandwidth. (Note that this interrupt is still generated in implicit mode).

 As soon as RegFifoRxByteAddr[7:0] >= start address + 4, the first 4 bytes (address) are stored in the FIFO data buffer.

These can be read and tested to see if the packet is destined for the radio and either remaining in Rx mode to receive

the packet or returning to sleep mode if not.

Receiver Timeout Operation

In either single or continuous LoRaTM reception modes, a receiver timeout functionality is available that permits the receiver

to listen for a pre-determined period of time before generating an interrupt signal to indicate that no valid packets have

been received. The timer is absolute and commences as soon as the radio is placed in either single or continuous receive

mode. The interrupt itself, RxTimeout, can be found in the interrupt register RegIrqFlags. In Rx Single mode, the device will

return in Stanby mode as soon as the interrupt occurs and the interrupt needs to be cleared before to return in Rx Single

mode. In Rx Continuous mode, the interrupt will interrupt will simply be raised but the device will stay in Rx Continous

mode. It is therefore the responsability on the controller to clear the interrupt while still in Rx Continuous mode. The

programmed timeout value is expressed as a multiple of the symbol period and is given by:

TimeOut = LoraRxTimeout

⋅ Ts

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