Data Sheet

LJ1269HC
Rev1.0 Page 35 Web: www.ljelect.com
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:
Figure 16. 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 RFM69HW 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 LJ1269HC , to optimize the delays when setting the Modulein
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:
Sub GHz FSK/OOK Transceiver Module DATASHEET
TS_TR=5μS+1.25×PaRamp+
1
2
×Tbit
TS_TR=5μs+
1
2
×Tbit