MRF39RA Datasheet, PDF (25/72 Pages) Microchip Technology – Low-Power, Integrated UHF Receiver

3.3.4 Stopping Listen Mode
To abort Listen mode operation, observe the following
procedure:
• Program RegOpMode with ListenOn = 0,
ListenAbort = 1 and the desired setting for the
Mode bits (Sleep, Stdby, FS, Rx or Tx mode) in a
single SPI access
• Program RegOpMode with ListenOn = 0,
ListenAbort = 0 and the desired setting for the
Mode bits (Sleep, Stdby, FS, Rx or Tx mode) in a
second SPI access.
3.3.5 RC Timer Accuracy
All timings of the Listen mode rely on the accuracy of
the internal low-power RC oscillator. This oscillator is
automatically calibrated at the device power-up. This is
a user-transparent process.
For applications enduring large temperature variations
and for which the power supply is never removed, RC
calibration can be performed on user request.
RcCalStart in RegOsc1 is used to trigger this
calibration and the flag RcCalDone automatically sets
when the calibration is over.
MRF39RA
3.4 Auto Modes
Automatic modes of packet handler can be enabled by
configuring the related parameters in RegAutoModes.
The Intermediate mode of the chip is called
IntermediateMode and the Enter and Exit conditions to
and from this Intermediate mode can be configured
through the parameters EnterCondition and
ExitCondition.
The Enter and Exit conditions cannot be used
independently of each other (i.e., both must be enabled
at the same time).
The initial and the final state is the one configured in the
mode in RegOpMode. The initial and final states can be
different by configuring the Modes register while the
chip is in Intermediate mode. The pictorial description
of the AutoModes is shown in Figure 3-6.
FIGURE 3-6:
AUTO MODES OF
PACKET HANDLER
Intermediate State
defined by IntermediateMode
EnterCondition
ExitCondition
Initial state defined
By Mode in RegOpMode
Final state defined
By Mode in RegOpMode
Some typical examples of AutoModes usage are
described below:
• Automatic reception (AutoRx):
- Mode = Rx
- IntermediateMode = Sleep
- EnterCondition = CrcOk
- ExitCondition = falling edge of FifoNotEmpty
 2015 Microchip Technology Inc.
DS40001778B-page 25