SX1231 SEMTECH [Semtech Corporation], SX1231 Datasheet - Page 34

• Manufacturer Part Number: SX1231
• Description: Low Power Integrated UHF Transceiver
• Manufacturer: SEMTECH [Semtech Corporation]

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:
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
4.2.3. Receiver Startup Time
It is highly recommended to use the built-in sequencer of the SX1231, 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:
Rev 2 - Nov 2009
ADVANCED COMMUNICATIONS & SENSING
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 27.
In Packet mode, the SX1231 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.
ModeReady
TxReady
XO Started and PLL is locked
(sequencer or user)
Tx startup request
TS
Figure 14. Tx Startup, FSK and OOK
_
TR
group delay
Analog
5 us
=
TS
5
μ
_
s
TR
+
0.5 x Tbit
. 1
TS_TR
=
Page 34
25
5
μ
×
s
PaRamp
+
1.25 x PaRamp
1
2
(only in FSK
×
mode)
Tbit
+
1
2
×
Tbit
Transmission of Packet
,
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SX1231