MAC Mode configuration
Medium Access Control (MAC) Mode configures two functions:
- Enables or disables the use of a Digi header in the 802.15.4 RF packet.
When the Digi header is enabled (MM = 0 or 3), duplicate packet detection is enabled as well as certain AT commands.
MAC Modes 1 and 2 do not include a Digi header, which disables many features of the device. All data is strictly pass-through. These modes are intended to provide some compatibility with third-party 802.15.4 devices. - Enables or disables MAC acknowledgment request for unicast packets.
When MAC ACK is enabled (MM = 0 or 2), transmitting devices send packets with an ACK request so receiving devices send an ACK back (acknowledgment of RF packet reception) to the transmitter. If the transmitting device does not receive the ACK, it re-sends the packet up to five times or until the ACK is received.
MAC Modes 1 and 3 disable MAC acknowledgment. Transmitting devices send packets without an ACK request so receiving devices do not send an ACK back to the transmitter.
Broadcast messages are always sent with the MAC ACK request disabled.
Sending a unicast message with MAC ACKs disabled is not intended to be a reliable form of communication, as no ACKs are produced by recipients.
The following table summarizes the functionality.
| Mode | Digi header | MAC ACK |
|---|---|---|
|
0 (default) |
X |
X |
|
1 |
|
|
|
2 |
|
X |
|
3 |
X |
|
The default value for the MM configuration parameter is 0 which enables both the Digi header and MAC acknowledgment.
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