Rainbow Electronics DS28EA00 - Manual (Page 24)

DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO
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Master-To-Slave
For a write-one time slot, the voltage on the data line must have crossed the V
TH
threshold before the write-one
low time t
W1LMAX
is expired. For a write-zero time slot, the voltage on the data line must stay below the V
TH
threshold until the write-zero low time t
W0LMIN
is expired. For the most reliable communication, the voltage on the
data line should not exceed V
ILMAX
during the entire t
W0L
or t
W1L
window. After the V
TH
threshold has been crossed,
the DS28EA00 needs a recovery time t
REC
before it is ready for the next time slot.
Figure 14. Read/Write Timing Diagram
Write-One Time Slot
RESISTOR MASTER
V
PUP
V
IHMASTER
V
TH
V
TL
V
ILMAX
0V
t
F
t
SLOT
t
W1L
ε
Write-Zero Time Slot
RESISTOR MASTER
t
REC
V
PUP
V
IHMASTER
V
TH
V
TL
V
ILMAX
0V
t
F
t
SLOT
t
W0L
ε
Read-Data Time Slot
RESISTOR MASTER DS28EA00
t
REC
V
PUP
V
IHMASTER
V
TH
V
TL
V
ILMAX
0V
Master
Sampling
Window
δ t
F
t
SLOT
t
RL
t
MSR
Slave-To-Master
A read-data time slot begins like a write-one time slot. The voltage on the data line must remain below V
TL
until the
read low time t
RL
is expired. During the t
RL
window, when responding with a 0, the DS28EA00 starts pulling the data
line low; its internal timing generator determines when this pulldown ends and the voltage starts rising again. When
responding with a 1, the DS28EA00 does not hold the data line low at all, and the voltage starts rising as soon as
t
RL
is over.