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Topic: Reset Pulse coming to fase (Read 557 times) previous topic - next topic

simon053

I recently had a problem with my Arduino board where someone had suggested that the reset pulse was coming too fast. To avoid this I added a 0.iuf capacitor as instructed to the ground and reset pin to delay the reset. This worked.
My problem is understanding how the reset process works and how it affects the board. Could anyone explain this process to me as I cannot find it on the arduino website or any where else??

Nick Gammon

Page 318 of the datasheet for the processor. Minimum reset pulse: 2.5 uS.

Also see pages 47/48 where they mention "Shorter pulses are not guaranteed to generate a reset.".

I'm no capacitor expert, but I believe the time it takes to charge the 0.1 uF capacitor ensures that the reset line is held low long enough.
http://www.gammon.com.au/electronics

simon053

Thanks for the help. It looks as though the shield is effecting the capacitance or resistance upon the power on reset. Adding the capacitor keeps the Reset pin active low long enough to complete the proper reset.


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