Rainbow Electronics DS1985 - Manual (Page 20)

DS1985
20 of 25
(Figure 11) should be applied for 480
µ
s, after which the bus master returns the data line to an idle high
state controlled by the pullup resistor. Note that due to the high voltage programming requirements for
any 1-Wire EPROM device, it is not possible to multidrop non-EPROM based 1-Wire devices with the
DS1985 during programming. An internal diode within the non-EPROM based 1-Wire devices will
attempt to clamp the data line at approximately 8 volts and could potentially damage these devices.
INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 9
480
µ
s
≤
t
RSTL
<
∞
*
480
µ
s
≤
t
RSTH
<
∞
(includes recovery time)
15
µ
s
≤
t
PDH
< 60
µ
s
60
µ
s
≤
t
PDL
< 240
µ
s
∗
In order not to mask interrupt signaling by other devices on the 1-Wire bus, t
RSTL
+ t
R
should always
be less than 960
µ
s.
READ/WRITE TIMING DIAGRAM Figure 10
Write-1 Time Slot
60
µ
s
≤
t
SLOT
< 120
µ
s
1
µ
s
≤
t
LOW1
< 15
µ
s
1
µ
s
≤
t
REC
<
∞
RESISTOR
MASTER
RESISTOR
MASTER
DS1985