RF69 datasheet(36/81 Pages) ETC2

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RF69

Page 36

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4.2.1. Transmitter Startup Time

The transmitter wake-up time, TS_TR, is given by the sequence controlled by the digital part. It is a pure digital delay which

depends on the bit rate and the ramp-up time. In FSK mode, this time can be derived from the following equation.

where PaRamp is the ramp-up time programmed in RegPaRamp and Tbit is the bit time.

In OOK mode, this equation can be simplified to the following:

Tx startup request

(sequencer or user)

TS_TR

XO Started and PLL is locked

Analog

group delay

0.5 x Tbit

1.25 x PaRamp

(only in FSK

mode)

Transmission of Packet

5 us

ModeReady

TxReady

Figure 17. Tx Startup, FSK and OOK

4.2.2. Tx Start Procedure

As described in the former section, ModeReady and TxReady interrupts warn the uC that the transmitter is ready to

transmit data

 In Continuous mode, the preamble bits preceding the payload can be applied on the DIO2/DATA pin immediately after

any of these interrupts have fired. The DCLK signal, activated on pin DIO1/DCLK can also be used to start toggling the

DATA pin, as described on Figure 30.

 In Packet mode, the RF69 will automatically modulate the RF signal with preamble bytes as soon as TxReady or

ModeReady happen. The actual packet transmission (starting with the number of preambles specified in PreambleSize)

will start when the TxStartCondition is fulfilled.

4.2.3. Receiver Startup Time

It is highly recommended to use the built-in sequencer of the RF69, to optimize the delays when setting the chip in

receive mode. It guarantees the shortest startup times, hence the lowest possible energy usage, for battery operated

systems.

The startup times of the receiver can be calculated from the following:

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