s-35399a03 Seiko Instruments Inc., s-35399a03 Datasheet - Page 39

• Manufacturer Part Number: s-35399a03
• Description: 2-wire Real-time Clock
• Manufacturer: Seiko Instruments Inc.

Rev.1.0
Reset After Communication Interruption
In case of communication interruption in the S-35399A03, for example, during communication the power supply voltage
drops so that only the master device is reset; the S-35399A03 does not operate the next procedure because the internal
circuit keeps the state prior to interruption. The S-35399A03 does not have a reset pin so that users usually reset its internal
circuit by inputting a stop condition. However, if the SDA line is outputting “L” (during output of acknowledgment signal or
Read), the S-35399A03 does not accept a stop condition from the master device. In this case, users are necessary to finish
acknowledgment output or Read the SDA line. Figure 49 shows how to reset. First, input a start condition from the master
device (The S-35399A03 cannot detect a start condition because the SDA line in the S-35399A03 is outputting “L”). Next,
input a clock pulse equivalent to 1-byte data access (9-clock) from the SCL line. During this, release the SDA line for the
master device. By this procedure, SDA I/O before interruption is finished, so that the SDA line in the S-35399A03 is
released. After that, inputting a stop condition resets the internal circuit so that restore the regular communication. This
reset procedure is recommended to perform at initialization of the system after rising the master device’s power supply
voltage.
S-35399A03)
master device)
(Output from
(Output from
_00
SDA
SDA
SDA
SCL
condition
Start
“L”
“L”
Figure 49 How to Reset
Seiko Instruments Inc.
Clocks equivalent to 1-byte data access
1
“L” or High-Z
“L” or High-Z
2
High-Z
8
2-WIRE REAL-TIME CLOCK
High-Z
High-Z
9
Stop condition
S-35399A03
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