Matrix Orbital PK202-25 - Manual (Page 35)

• 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
0 1 Flags The flags 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.
Matrix Orbital PK202-25 31