Specifications

Chapter 3 – Input/Output Interfaces
72 PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Boo
k
END OF
FRAME
DATA
ONE FRAME
START BIT
APPEARS
START OF
io_out()
t
fout
87654321
TIME
SERIAL
OUTPUT
START START
STOP
END OF
io_in()
t
ret
Symbol Description Typ @ 10MHz
t
fout
Function call to start bit 79 µs
t
ret
Return from function 10 µs
Figure 3.32 Serial Output
The duration of this function call is a function of the number of data bits transferred and the transmission bit rate. As an
example, to output 100 bytes at 300 bits/second would require a time duration of (100 x 10 x 1/300) + t
fout
+ t
ret
.
Touch Input/Output
The Touch I/O object enables easy interface to any slave device which adheres to Dallas Semiconductor’s 1-Wire
®
Memory standard. This interface is a one-wire, open-drain, bidirectional connection.
Up to eight 1-Wire Memory busses can be connected to a PL Smart Transceiver through the use of the first eight I/O
pins, IO0 – IO7. The only additional component required for this is a pull-up resistor on the data line (refer to the 1-Wire
Memory specification below on how to select the value of the pull-up resistor). The high current sink capabilities of IO0
– IO3 pins of the PL Smart Transceiver can be used in applications where long wire lengths are required between the 1-
Wire Memory device and the PL Smart Transceiver.
The slave acquires all necessary power for its operation from the data line. Upon physical connection of a 1-Wire
Memory device to a master (in this case the PL Smart Transceiver), the 1-Wire Memory generates a low presence pulse
to inform the master that it is awaiting a command. The PL Smart Transceiver can also request a presence pulse by
sending a reset pulse to the 1-Wire Memory device.
Commands and data are sent bit by bit to make bytes, starting with the LSB. The synchronization between the PL Smart
Transceiver and the 1-Wire Memory devices is accomplished through a negative-going pulse generated by the PL Smart
Transceiver.
Figure 3.33 shows the details of the reset pulse in addition to the read/write bit slots.
Note: NodeBuilder 3.1., Mini EVK 1, or later, features the ability to adjust the t
low
, t
wrd
, and t
rdi
timing values.