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[NETIMPRESS Common] How to deal with the watchdog timer on the target board

  • Updated
If the watchdog timer on the target board operates and a reset occurs
while programming with the programmer, it is necessary to take measures
to stop the watchdog timer.
  • If watchdog monitoring is performed by an external reset IC, etc.,
    outside the microcomputer, the software programmed to the microcomputer
    is not running during flash memory programming (a state where pulses
    are not output from a specific port of the microcomputer). Therefore,
    if the operation of the watchdog is not stopped, the microcomputer
    will be reset during flash memory programming, and the programming
    will be interrupted.
Check the circuit diagram of the target board, confirm the model name
of the reset IC, etc. that generates the watchdog reset, and check the device
specifications in the datasheet. Please consider one of the following
countermeasures:

  • When inputting a pulse using the WDT (Watchdog pulse signal)
    of the programmer

    Check the period of the input pulse (typ.) and, if necessary, change
    the WDT Clock Period setting of the programmer (default is 20ms)
    to match the device specifications.

    *Since the WDT output of the programmer is an open collector output,
      a pull-up resistor (recommended 10kΩ) is required on the fixture, etc.

     

  • When there is a pin to disable the watchdog timer and you want 
    to use it

    Check the logic settings, etc. to disable it. 
      Example: If setting the WD enable pin to Low disables the watchdog
      operation
      -> Connect the WD enable pin to GND on the fixture during flash
           programming to stop the watchdog operation.

    *Depending on the definition program, the output of the WDT pulse
     from the programmer can sometimes be switched between
     "Output only when executing device function" and "Constant output" 
     in the Parameter Table 2 settings. Since the setting method varies
     depending on the definition program, please check the FAQ describing
     the setting method for each definition program if necessary.
     

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