OWIRE
signal
Master
drives low
Master releases
to float high
Slave may
sample here (to
see if low or high)
60 µs
OWIRE
signal
Master
drives low
Master
releases to
float high
Slave may
sample here
(to see if low
or high)
60 µs
15 µs or less
Functional Description
1503
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
1-Wire Master Module
15 µs, a value of 0 is registered.
depicts a 1-Wire Master transmitting a 1 to a slave.
shows a 1-wire Master
transmitting a 0 to a slave.
Figure 22-3. 1-Wire Master Transmitting a 1
Figure 22-4. 1-Wire Master Transmitting a 0'
For a read from the slave, the Master drives and holds the line low for at least 1 µs (but less than 15 µs)
and then releases. A typical hold time is 6 µs; in other words, it uses a transmitted 1. The read is
performed as:
•
A 1 is signaled by the slave when "does nothing." Thus, the slave just allows the line to come back up
when the master releases it. The master samples the line at 15 µs after the low edge and the line is
still high, signaling a 1.
•
If the slave holds the line down for more than 5 µs (and no more than 60 µs), a 0 is signaled. The
master samples the line at 15 µs after the low edge, and because the line is low still, it is treated as a
0.
depicts a Master receiving a 1 value from a slave.
shows the slave sending a 0
value to a Master.