AX-ConfigurationUtility User Manual
26
your length field counts the number of bytes excluding the length field itself.
Negative values for “len offset” are allowed.
•
If you check “enable
len field
” in HDLC mode, the TX will send a length
field, but
it will be ignored by the RX.
•
Specifying a maximum packet length can limit the impact of bit errors in the
length field.
•
If the acknowledge feature is used an ACK sequence number field can be
configured. This is not mandatory for acknowledge to work. However, without this
field the SLAVE cannot detect duplicate packets occurring if packet RX has worked
but the ACK packet got lost, causing the MASTER to retransmit the packet.
•
Specify a device addresses of up to 4 bytes and a corresponding address mask to
restrict reception to packets containing a matching address.
•
“address position” specifies
the starting position of the address inside the packet.
Zero corresponds to the byte immediately after the SYNC WORD / HDLC flag.
•
Optionally the sender’s address can be added to the header. Note that address
works on the destination address field (containing the slave’s address in normal
MASTER to SLAVE communication and the master’s address for packe
ts sent from
SLAVE to MASTER, e.g. ACK packets in the demo firmware.)
DATA
•
The DATA field allows you to specify a static sample payload which will be used by
the demo firmware.
Enter each byte as a two-digit hex number (without leading 0x). Bytes may be
separated by spaces.
•
Optionally the firmware can insert a 16-bit counter into the data field at a
specified position. This allows the RX to count the number of lost packets. The
two bytes reserved for this counter are displayed as “00 00” in the data field.
•
Checking the “send MSB first” button causes each byte in the DATA field to be
sent MSB first. Otherwise each byte is sent LSB first.
Note, however, that preamble character and SYNC WORD are always sent MSB
first. (Technically, the RF chip will be configured to operate in MSB first or LSB
first mode according to the “MSB first button”
, which applies to every byte.
However, in LSB first mode the AX-ConfigurationUtility GUI reverses the entered
preamble and SYNC WORD bytes to keep the representation in the GUI MSB first.
The reason for this is, that the byte and nibble order of a SYNC WORD written left
to right but read LSB first can be confusing.)
•
“CRC SKIP FIRST” causes the first byte of the packet to be excluded from CRC
calculation.
CRC
•
Select CRC algorithm and initial value.
