4 display 1-wire connections – Matrix Orbital PK202-25 User Manual

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• Read ROM [33h]: All devices will begin transmitting their address after this command. This

command will only succeed when there is one device on the bus. When multiple devices are present,

all devices will begin transmitting their addresses, overlapping each other. This command can be used

to determine if there is more than one device on the bus. After the address has been read back, if the

CRC is valid, there is only one device on the bus. Otherwise, there are multiple devices on the bus and

each address must be searched out.

7.4 Display 1-Wire Connections

The transaction command allows data to be put onto the bus and read off the bus for transactions. And

the search command identifies all the devices on the bus for further communication.

7.4.1 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

Flags

The flags byte controls the optional

components of the transaction.

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.

Recieve Bits

The number of bits to read off the

bus after the data to be put on the

bus has been sent.

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.

Matrix Orbital

PK202-25