Re: Can I noise hang a ColdFire forever...?

Dear Nicolas
Thanks for your help!
In fact it is a not god practice and shall not be used, but I did it  in order to evaluate ColdFire featues related to
reset question.
I understood that if it is not damaged ( I can reset it manually and it works again) I thought it should at least reset after such disturb.
Shoud not the watchdog circuit resets de cpu if it is not refreshing it anymore?
Despite my question above, I have on mind (but I´m trying to not see it...)  that depending of the distrub intensity the cpu logical blocks could be set to an unpredictable state, in this case I would understand why it stops forever...
Ricardo Raupp

  ----- Original Message ----- 
  From: Nicolas Pinault 
  To: Ricardo 
  Sent: Friday, March 07, 2008 4:36 AM
  Subject: Re: [ColdFire] Can I noise hang a ColdFire forever...?


  Ricardo,

  Using a relay without a freewheeling diode is unacceptable. ALL the electronics is in danger. When a relay transition from on state to of state, a (very) high voltage is generated accross its coil pins. This can make a standart 5V or 3.3V power voltage go (very) higher than its specified voltage. This in turn damages the electronic component of the board. The best case is a reset of the board. But it can also destroy the board.
  You must add the diode on the relay coil pins.

  Nicolas

  Ricardo Raupp a écrit : 
    Hi people
    I´m using a 5213 target and it hangs up after a turn off a close 12V/35mA relay wich doesn´t have freewheling diode, that is, generating a noise.
    I´m using watchdog and others interrupts in order to make it resets, but "sometimes" it is not enought, the cpu
    simply stops and only by a hw reset it turns to work back.
    I´m not concerned about the reset issue,but about the hang forever detail....reset after noise is acceptable e expectaed, but hang up ...never...:(:( ??
    My question:
    - Is ColdFire able to "allways" reset after a disturb (conducted or induced)?or should I use a external watchdog?Some special care to assure reset allways?
    Thanks
    Ricardo Raupp

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