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9100-0425-01
Example 2 - Using a Longer Message:
The Host sends:
AA 21 27 10 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 11 22 33 44 55 66 77 88 99 AA 44
56 78 <CRC-low> <CRC-high>
Note:
The length field, the command contains a total of 33 bytes. The length is 21 Hexadecimal,
which is equal to 33 decimal.
The SmartOne Responds:
AA 05 27 <CRC-low> <CRC-high>
What actually goes out over the air is:
12 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 11 22 33 44 55 66 77 88 99 AA 44 56 78 00
00 00 00 00 00 00 00
Note:
All on air messages are padded to a multiple of 9 bytes. This is the reason for the trailing
zeros in this example.
A simple ACK or NAK from the SmartOne Device to the host (smart sensor):
ACKs.
AA 05 26 <crc crc> (for the Truncated message)
AA 05 27 <crc crc> (for the Raw message)
NAK:
AA 05 FF <crc crc> (NAK).
Note:
As the SmartOne operates, some debugging traces come out of the serial port. Those
traces should simply be ignored. Once the handshake line is pulled low, the unit is in
"command mode" and debugging traces will stop.
Note:
User
commands
acknowledgement or a NAK (as shown in the examples above).
acknowledgement (or NAK) is received, the host should simply ignore the serial port until
the next time it sends a command.
Note:
The most common reasons for a NAK are incorrect CRC, incorrect length field, or
incorrect command field (i.e. not 0x26 or 0x27 for trunc and raw respectively).
The Handshake Line
The handshake line should be pulled low before sending each serial message. The recommended use of
the handshake line is:
1) Pull handshake low.
2) Wait 2-3 milliseconds.
3) Send command
4) Receive response.
5) Raise handshake high.
SmartOne Solar™ User Guide v1.0.3
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