Re: 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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