DS3900K# Maxim Integrated Products, DS3900K# Datasheet - Page 10

• Manufacturer Part Number: DS3900K#
• Description: Power Management Modules & Development Tools 2-WIRE BUS INTERFACE NTERFACE EV KIT ROHS
• Manufacturer: Maxim Integrated Products

Specifications of DS3900K#

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Serial Communications Module
For Evaluation Kits
For technical support email [e-mail].
10
Pulse function not operating properly
DS3900 not found by software after
reset
2-wire communication errors
or general communication errors
SDA or SCL line is stuck low
Bit I/O operation not working as
expected
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SYMPTOM
Power might not be applied to the
DS3900, DTR might not be in the correct
state for the DS3900 to operate, the LED
might be connected improperly, or P3
might have been used previously by the
software as an input.
The serial cable is not connected, the
DS3900 is not firmly seated on the
application board, power is not applied
to DS3900, or another piece of software
is controlling the serial port.
Either the PC cannot communicate with
the DS3900, or the DS3900 cannot
communicate with the 2-wire device.
If only SDA is held low, the 2-wire bus
might have been disturbed while a slave
was controlling the bus during a read
operation. Additionally, P10 and P11
may have been used as bit I/O pins and
the last program left the pins in a low
state.
P3 is being used, and the pulse function
is operating and changing the state of
the pin.
CAUSES
Ensure that power is applied to the circuit and
that DTR is on. Verify that LED is connected
properly. If none of the above works, cycle
power or issue a bit I/O write to P3 to ensure
that P3 is enabled as an output.
Make sure the serial cable is connected from
the PC to the DS3900’s DB9 connector. If
multiple serial ports are present on the back of
the PC, ensure the proper port has been
connected. Ensure the DS3900 is well seated
on the application board and that power has
been applied. Check for other software that
may be controlling the serial port.
Verify the DS3900 is not held in reset by the
DTR signal. Verify the pullups for SDA and
SCL are on if the application board does not
have pullups. Verify the 2-wire device is being
addressed correctly by the software. Verify
power is applied to the both the DS3900 and
the 2-wire device. Verify the serial cable is
properly connected from the PC to the
DS3900. Verify the DS3900 is properly seated
on the application board.
Try to issue a bit I/O read command to the pin
that is stuck low, and the bus will be freed by
the DS3900. If SDA remains low, a slave
device is controlling it. Reset the 2-wire bus
(clock the bus nine times, and issue a stop
command) or cycle power to the application
board to free the pin.
Disable the pulse with software, or do not use
P3 for an input or output.
SOLUTION(S)
Troubleshooting