AC4490 User Guide
Version 4.5
Laird Connectivity Solutions Support Center:
http://ews-support.lairdtech.com
21
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Enhanced API Receive Packet
Note: Implemented in firmware v.6.7 and later.
When Enhanced API Receive Packet is enabled, all packets received by the transceiver include the MAC
address of the source radio as well as an RSSI indicator which can be used to determine the link quality
between the two. API Receive Packet is enabled when bit-0 of the Enhanced API Control byte is enabled.
Upon receiving a packet the radio sends its OEM Host the packet in the following format:
0x81
Payload Data Length (0x01 – 0x50)
Laird Use
RSSI*
Source MAC
(2, 1, 0)
Payload Data
Note: When both API Send Data Complete and API Receive Packet are enabled, the Send Data Complete
will be received before the transceiver sees the Receive API Packet. This may be reversed when the
API Send Data Complete is missed and is being resent after the API Receive Packet is received.
Note: If Enhanced API Receive is enabled, the Receive API feature should be disabled by setting EEPROM
byte 0xC1 to 0xFF.
API Transmit Packet
Note: Implemented in firmware v6.7 and later.
API Transmit Packet is a powerful command that allows the OEM host to dynamically send data to a single or
multiple (broadcast) transceiver(s) on a packet-by-packet basis. API Transmit Packet is enabled when bit-1 of
the Enhanced API Control byte (EEPROM byte 0xC6) is enabled. The OEM host must use the following format
to transmit a packet over the RF when using Transmit API packets:
0x81
Payload Data Length
(0x01 – 0z50)
Laird Use
Transmit Retries/
Broadcast Attempts
Destination MAC
(2, 1, 0)
Payload Data
If the OEM Host does not encode the header correctly, the transceiver sends the entire string (up to 80
bytes) and looks for the header in the next data.
Although the seven bytes of overhead are not sent over the RF, they are kept in the buffer until the
packet is sent. Keep this in mind so as not to overrun the 256-byte buffer.
Setting the Destination MAC to 0xFF 0xFF 0xFF broadcasts the packet to all available transceivers.
Note: If the OEM host does not properly encode the header of the Tx API packet, the string (up to 80
bytes) is sent to the MAC address from the header of the last known good Tx API encoded packet.
API Send Data Complete
Note: Implemented in v6.7 of the firmware and later.
API Send Data complete can be used as a software acknowledgement indicator. When a radio sends an
addressed packet, it looks for a received acknowledgement (transparent to OEM host). If an
acknowledgement is not received, the packet is retransmitted until one is received or all retries are used.
