
142
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
Register Bits
Value
Description
0x2
...
0xF
Retransmission of frame is attempted 15
times.
Bit 3:1 – MAX_CSMA_RETRIES2:0 - Maximum Number of CSMA-CA Procedure
Repetition Attempts
MAX_CSMA_RETRIES specifies the number of retries in TX_ARET mode to repeat the
CSMA-CA procedure before the transaction gets canceled. According to IEEE 802.15.4
the valid range of MAX_CSMA_RETRIES is 0 to 5. A value of MAX_CSMA_RETRIES =
7 initiates an immediate frame transmission without performing CSMA-CA. This may
especially be required for slotted acknowledgment operation. MAX_CSMA_RETRIES =
6 is reserved.
Table 9-74 MAX_CSMA_RETRIES Register Bits
Register Bits
Value
Description
MAX_CSMA_RETRIES2:0
0x0
No repetition of CSMA-CA procedure
0x1
One repetition of CSMA-CA procedure
0x2
...
0x5
Five repetitions (highest IEEE 802.15.4
compliant value)
0x6
Reserved
0x7
Immediate frame re-transmission without
performing CSMA-CA
Bit 0 – SLOTTED_OPERATION - Set Slotted Acknowledgment
When using RX_AACK mode in networks operating in beacon or slotted mode
according
to
IEEE
802.15.4-2006,
chapter
5.5.1
the
register
bit
SLOTTED_OPERATION indicates that acknowledgment frames are to be sent on back-
off slot boundaries (slotted acknowledgment). If this register bit is set the
acknowledgment frame transmission has to be initiated by the application software
using bit SLPTR of register TRXPR. This waiting state is signaled in sub register
TRAC_STATUS of register TRX_STATE with value SUCCESS_WAIT_FOR_ACK.
Table 9-75 SLOTTED_OPERATION Register Bits
Register Bits
Value
Description
SLOTTED_OPERATION
0
The radio transceiver operates in unslotted
mode. An acknowledgment frame is
automatically sent if requested.
1
The transmission of an acknowledgment
frame has to be controlled by the
microcontroller.
9.12.51 CSMA_SEED_0 – Transceiver CSMA-CA Random Number Generator Seed Register
Bit
7
6
5
4
3
2
1
0
NA ($16D)
CSMA_SEED_07:00
CSMA_SEED_0
Read/Write
RW
Initial Value
1
0
1
0
1
0