3 rx_aack_on - receive with automatic ack, Atmega128rfa1 – Rainbow Electronics ATmega128RFA1 User Manual
Page 46
46
8266A-MCU Wireless-12/09
ATmega128RFA1
o
Handling of Pending Data Indicator
o
Characterize as PAN coordinator
o
Handling of Slotted Acknowledgement
•
Additional Frame Filtering Properties (register XAH_CTRL_1, CSMA_SEED_1)
o
Promiscuous Mode
o
Enable or disable automatic ACK generation
o
Handling of reserved frame types
The addresses for the address match algorithm are to be stored in the appropriate
address registers. Additional control of the RX_AACK mode is done with registers
XAH_CTRL_1 and CSMA_SEED_1.
As long as a short address has not been set, only broadcast frames and frames
matching the IEEE address can be received.
Configuration examples for different device operating modes and handling of various
frame types can be found in section
"Description of RX_AACK Configuration Bits" on
TX_ARET configuration steps:
•
Leave register bit TX_AUTO_CRC_ON = 1 register TRX_CTRL_1
•
Configure CSMA-CA
o
MAX_FRAME_RETRIES register XAH_CTRL_0
o
MAX_CSMA_RETRIES
register XAH_CTRL_0
o
CSMA_SEED
registersCSMA_SEED_0, CSMA_SEED_1
o
MAX_BE, MIN_BE
register CSMA_BE
•
"Configuration and CCA Request" on page 71
)
MAX_FRAME_RETRIES (register XAH_CTRL_0) defines the maximum number of
frame retransmissions.
The register bits MAX_CSMA_RETRIES (register XAH_CTRL_0) configure the number
of CSMA-CA retries after a busy channel is detected.
The CSMA_SEED_0 and CSMA_SEED_1 registers define a random seed for the back-
off-time random-number generator of the radio transceiver.
The MAX_BE and MIN_BE register bits (register CSMA_BE) set the maximum and
minimum CSMA back-off exponent (according to
)
.
9.4.2.3 RX_AACK_ON – Receive with Automatic ACK
The general functionality of the RX_AACK procedure is shown in
48.
The gray shaded area is the standard flow of a RX_AACK transaction for
IEEE 802.15.4 compliant frames (refer to section
"Configuration of IEEE Scenarios" on
page 50). All other procedures are exceptions for specific operating modes or frame
formats (refer to section
"Configuration of non IEEE 802.15.4 Compliant Scenarios" on
page 52).
The frame filtering operation is described in detail in section
54.
In RX_AACK_ON state, the radio transceiver listens for incoming frames. After
detecting SHR and a valid PHR, the radio transceiver parses the frame content of the
MAC header (MHR) as described in section
"PHY Header (PHR)" on page 61.