MRF24J40_08 Datasheet, PDF (99/152 Pages) Microchip Technology – IEEE 802.15.4™ 2.4 GHz RF Transceiver

3.8.1.6 Configuring Beacon-Enabled Device
The following steps configure the MRF24J40 as a
device in a beacon-enabled network:
1. Set the SLOTTED (TXMCR 0x11<5>) bit = 1 to
use Slotted CSMA-CA mode.
2. Set the OFFSET (FRMOFFSET 0x23<7:0>)
value = 0x15 for optimum timing alignment.
3. Calibrate the Sleep Clock (SLPCLK) fre-
quency. Refer to Section 3.15.1.2 “Sleep
Clock Calibration”.
4. Program the associated coordinator’s 64-bit
extended address to the ASSOEADR registers
(0x230-0x237).
5. Program the associated coordinator’s 16-bit
short address to the ASSOSADR registers
(0x238-0x239).
Note:
The device will align its beacon frame with
the associated coordinator’s beacon
frame only when the source address
matches the ASSOEADR or ASSOSADR
value.
6. Parse the received associated coordinator’s
beacon frame and extract the values of BO and
SO. Calculate the inactive period and program
the Main Counter, MAINCNT (0x229<1:0>,
0x228, 0x227, 0x226), and Remain Counter,
REMCNT (0x225, 0x224), according to the BO
and SO values. Refer to Section 3.15.1.3
“Sleep Mode Counters”.
7. Program the CAP end slot (ESLOTG1
0x13<3:0>) value.
3.8.1.7
Configuring Beacon-Enabled GTS
Settings for Device
The following steps configure the MRF24J40 as a
device in a beacon-enabled network with Guaranteed
Time Slots:
1. Set the GTSON (GATECLK 0x26<3>) bit = 1 to
enable the GTS FIFO clock.
2. Parse the received beacon frame and obtain the
GTS allocation information. Program the end
slot value of the CAP and each GTS into the
ESLOT registers, as shown in Table 3-9.
3. Set the GTSSWITCH (TXPEND 0x21<1>) bit = 1
so that if a TXGTS1FIFO or TXGTS2FIFO trans-
mission error occurs, it will switch to another
TXGTSxFIFO.
MRF24J40
3.8.2 NONBEACON-ENABLED NETWORK
A nonbeacon-enabled network does not transmit a
beacon unless it receives a beacon request, and hence,
does not have any superframe structure. A
nonbeacon-enabled network uses unslotted CSMA-CA
to access the medium. The unslotted CSMA-CA is
explained in Section 3.9 “Carrier Sense Multiple
Access-Collision Avoidance (CSMA-CA) Algo-
rithm”. For nonbeacon-enabled networks, both BO and
SO are set to 15. Guaranteed Time Slots (GTS) are not
supported, and generally, devices require less comput-
ing power as there are no strict timing requirements that
need to be met.
3.8.2.1
Configuring Nonbeacon-Enabled
PAN Coordinator
The following steps configure the MRF24J40 as a
coordinator in a nonbeacon-enabled network:
1. Set the PANCOORD (RXMCR 0x00<3>) bit = 1
to configure as the PAN coordinator.
2. Clear the SLOTTED (TXMCR 0x11<5>) bit = 0
to configure Unslotted CSMA-CA mode.
3. Configure BO (ORDER 0x10<7:4>) value = 0xF.
4. Configure SO (ORDER 0x10<3:0>) value = 0xF.
3.8.2.2
Configuring Nonbeacon-Enabled
Device
The following steps configure the MRF24J40 as a
device in a nonbeacon-enabled network:
1. Clear the PANCOORD (RXMCR 0x00<3>) bit = 0
to configure as device.
2. Clear the SLOTTED (TXMCR 0x11<5>) bit = 0
to use Unslotted CSMA-CA mode.
© 2008 Microchip Technology Inc.
Preliminary
DS39776B-page 97