ds2482-101 Maxim Integrated Products, Inc., ds2482-101 Datasheet - Page 17

• Manufacturer Part Number: ds2482-101
• Description: Single-channel 1-wire Master With Sleep Mode
• Manufacturer: Maxim Integrated Products, Inc.

Figure 10. I
The following terminology is commonly used to
describe I
defined in Figure 10.
SDA
SCL
NOTE: TIMING IS REFERENCED TO V
Single-Channel 1-Wire Master with Sleep Mode
Bus Idle or Not Busy: Both SDA and SCL are inac-
tive and in their logic-high states.
START Condition: To initiate communication with a
slave, the master must generate a START condition.
A START condition is defined as a change in state of
SDA from high to low while SCL remains high.
STOP Condition: To end communication with a
slave, the master must generate a STOP condition. A
STOP condition is defined as a change in state of
SDA from low to high while SCL remains high.
Repeated START Condition: Repeated STARTs are
commonly used for read accesses to select a spe-
cific data source or address to read from. The mas-
ter can use a repeated START condition at the end
of a data transfer to immediately initiate a new data
transfer following the current one. A repeated START
condition is generated the same way as a normal
START condition, but without leaving the bus idle
after a STOP condition.
Data Valid: With the exception of the START and
STOP condition, transitions of SDA can occur only
during the low state of SCL. The data on SDA must
remain valid and unchanged during the entire high
pulse of SCL plus the required setup and hold time
(t
HD:DAT
STOP
2
2
C Timing Diagram
t
BUF
C data transfers. The timing references are
after the falling edge of SCL and t
START
______________________________________________________________________________________
t
HD:STA
IL(MAX)
t
LOW
AND V
IH(MIN)
t
R
.
I
t
HD:DAT
2
C Definitions
t
HIGH
SU:DAT
t
F
t
SU:DAT
REPEATED
START
before the rising edge of SCL; see Figure 10). There
is one clock pulse per bit of data. Data is shifted into
the receiving device during the rising edge of SCL.
When finished with writing, the master must release
the SDA line for a sufficient amount of setup time
(minimum t
rising edge of SCL to start reading. The slave shifts
out each data bit on SDA at the falling edge of the
previous SCL pulse and the data bit is valid at the
rising edge of the current SCL pulse. The master
generates all SCL clock pulses, including those
needed to read from a slave.
Acknowledge: Typically a receiving device, when
addressed, is obliged to generate an acknowledge
after the receipt of each byte. The master must gen-
erate a clock pulse that is associated with this
acknowledge bit. A device that acknowledges must
pull SDA low during the acknowledge clock pulse in
such a way that SDA is stable low during the high
period of the acknowledge-related clock pulse plus
the required setup and hold time (t
falling edge of SCL and t
edge of SCL).
Not Acknowledged by Slave: A slave device may
be unable to receive or transmit data, for example,
because it is busy performing some real-time func-
tion or is in sleep mode. In this case, the slave
device does not acknowledge its slave address and
leaves the SDA line high. A slave device that is
ready to communicate acknowledges at least its
t
SU:STA
t
HD:STA
SU:DAT
+ t
SUPPRESSION
R
SPIKE
in Figure 10) before the next
SU:DAT
t
SP
before the rising
HD:DAT
t
SU:STO
after the
17