6.4.1 Transaction command (254 C8 1 [flags] [Send Bits] [Recieve bits]
[Send data])
The transaction command will perform a single transaction on the 1-wire bus in this order;
1. Bus Reset.
2. Transmit data onto the bus.
3. Receive data from the bus.
Table 16: 1-Wire Transaction
Offset
(Bytes)
Length
(Bytes)
Name
Description
0
1
Flags
The flag byte controls the optional
components of the transaction.
1
1
Send Bits
The number of bits that will be
transmitted onto the bus. The actual
bits to be transmitted are held in the
Send Data section.
2
1
Recieve Bits
The number of bits to read off the
bus after the data to be put on the
bus has been sent.
3
Variable
Send Data
The data to be transmitted onto the
bus. The data is transmitted MSB
to LSB in the order that they are re-
ceived.
Table 17: 1-Wire Flags
Bit
Description
7
6
Unused
5
(0 for future compatibility)
4
3
Add a CRC8 to the end of the transmitted data
2
Unused (0 for future compatibility)
1
Assume last received byte is a CRC8 and validate it
0
Reset bus before transaction
The received data is sent back using the “Display return protocol”. The return type will be 0x31 or ’1’,
and the error codes are described in the Table below.
Matrix Orbital
LK204-24-USB
27
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