Rainbow Electronics ATmega128RFA1 - Manual (Page 130)

130
8266A-MCU Wireless-12/09
ATmega128RFA1
• Bit 4 – AACK_DIS_ACK - Disable Acknowledgment Frame Transmission
If this bit is set no acknowledgment frames are transmitted in RX_AACK Extended
Operating Mode even if requested.
• Bit 3 – AACK_I_AM_COORD - Set Personal Area Network Coordinator
This register bit has to be set if the node is a PAN coordinator. It is used for address
filtering in RX_AACK.
• Bit 2:0 – CSMA_SEED_12:10 - Seed Value for CSMA Random Number
Generator
These bits contain the bits [10:8] of the CSMA_SEED. The lower part is defined in
register CSMA_SEED_0. See register CSMA_SEED_0 for details.
9.12.47 CSMA_BE – Transceiver CSMA-CA Back-off Exponent Control Register
Bit 7 6 5 4
NA ($16F) MAX_BE3 MAX_BE2 MAX_BE1 MAX_BE0 CSMA_BE
Read/Write RW RW RW RW
Initial Value 0 1 0 1
Bit 3 2 1 0
NA ($16F) MIN_BE3 MIN_BE2 MIN_BE1 MIN_BE0 CSMA_BE
Read/Write RW RW RW RW
Initial Value 0 0 1 1
This register controls the back-off exponent for the CSMA-CA procedure.
• Bit 7:4 – MAX_BE3:0 - Maximum Back-off Exponent
These register bits define the maximum back-off exponent used in the CSMA-CA
algorithm to generate a pseudo random number for back off the CCA. For details refer
to IEEE 802.15.4-2006, section 7.5.1.4. Valid values are 3 to 8.
Table 9-70 MAX_BE Register Bits
Register Bits Value Description
1 This value is not valid for the maximum
back-off exponent.
2 This value is not valid for the maximum
back-off exponent.
3 Minimum, IEEE compliant value for the
maximum back-off exponent.
4 ...
MAX_BE3:0
8 Maximum, IEEE compliant value for the
maximum back-off exponent.
• Bit 3:0 – MIN_BE3:0 - Minimum Back-off Exponent
These register bits define the minimum back-off exponent used in the CSMA-CA
algorithm to generate a pseudo random number for back off the CCA. For details refer
to IEEE 802.15.4-2006, section 7.5.1.4. Valid values are MAX_BE, MAX_BE-1), ..., 0.
If MIN_BE = 0 and MAX_BE = 0 the CCA back off period is always set to 0.