Matrix Orbital LK162-12 - Manual (Page 24)

20
7.5 Dallas One-Wire
5.1 Search for a
One-Wire Device Dec
Hex
ASCII 254 200 2
FE C8 02
■ ╚
SOT
v5.1
Sends a search query to each of the up to 32 devices on the one wire bus. Any connected device will respond with
an identification packet.
Response Bytes [14] Dallas One-Wire identification packet as shown below.
Table 14: Dallas One-Wire Packet Information
Offset Length Value Description
0 2 9002 Preamble
2 1
138 Another device packet will follow OR
10 Last device packet
3 1 49 Packet Type
4 1 0 Error Code (0 indicates success)
5 8 Device Address
13 1 0 CRC8 address check (0 indicates validity)
5.2 Dallas One-Wire
Transaction Dec
Hex
ASCII 254 200 1
FE C8 01
■ ╚
STX
Flags Send Bits Receive Bits Data
Flags Send Bits Receive Bits Data
Flags Send Bits Receive Bits Data v5.1
Performs a single Dallas 1-Wire transaction. Consult your device documentation for information regarding device
specific protocols. If an error is encountered, a corresponding value will be returned by the device.
Flags Byte Flags for transaction, see below.
Send Bits Byte Number of bytes to be sent to the device.
Receive Bits Byte Number of bytes expected to be received from the device.
Data Byte(s) Data to be transmitted LSB to MSB.
Table 15: Dallas One-Wire Flags
Bit Flag Description
7
6 Unused
5
4 0 (Future Compatibility)
3 Add CRC8 to transaction
2 0 (Future Compatibility)
1 Read CRC8 from transaction
0 Reset Bus prior to transaction
Table 16: Dallas One-Wire Errors
Code Error Description
0 Success
1 Unknown Command
2 No Devices Found
3 Fatal Search Error