Read-time slots, Figure 12. 1-wire write- and read-time slots, S minimum recovery time, t – Rainbow Electronics DS2740 User Manual
Page 13: Between cycles. see figure 12 for more information
DS2740
13 of 15
READ-TIME SLOTS
A read-time slot is initiated when the bus master pulls the 1-Wire bus line from a logic-high level to a
logic-low level. The bus master must keep the bus line low for at least 1
m
s and then release it to allow the
DS2740 to present valid data. The bus master can then sample the data t
RDV
from the start of the read-
time slot. By the end of the read-time slot, the DS2740 releases the bus line and allows it to be pulled
high by the external pullup resistor. All read-time slots must be t
SLOT
in duration with a 1
m
s minimum
recovery time, t
REC
, between cycles. See Figure 12 for more information.
Figure 12. 1-WIRE WRITE- AND READ-TIME SLOTS
LINE TYPE LEGEND:
Bus master active low
DS2740 active low
Resistor pullup
Both bus master and
DS2740 active low
t
SLOT
V
PULLUP
GND
READ 0 SLOT
READ 1 SLOT
t
SLOT
t
REC
>1
ms
t
RDV
Master Sample Window
Master Sample Window
t
RDV
V
PULLUP
GND
t
SLOT
Standard
t
LOW1
t
SLOT
WRITE 0 SLOT
WRITE 1 SLOT
t
LOW0
t
REC
>1
ms
DS2740 Sample Window
MIN
TYP
MAX
15
ms
15
ms
30
ms
DS2740 Sample Window
MIN
TYP
MAX
15
ms
15
ms
30
ms
2
ms
Overdrive
Mode
1
ms
3
ms
1
ms
2
ms
3
ms