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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

6 Unused

5 (0 for future compatibility)

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

1 2 ... 26 27 28 29 30 31 32 33 34 35 36 ... 48 49

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Matrix-orbital LK204-24-USB Bedienungsanleitung Seite 31