CODEWITHSUNDEEP
arduinoarduino-uno
HixField
HixField

Reputation: 3796

Arduino button interrupt triggered on high power switch on

I have a nearly finished prototype using an arduino uno. Basically its purpose is to switch a 2000w main AC heating load using a heavy relay on and off. The input of the relay is comming from the mains but is connected to the power company using a special meter that is only switched on between 23-07 hrs at night. The power for the arduino is continous by the way, so this stays on.

The whole thing is nicely build into a box with on the front an small lcd display and a button, connected using 20cm wires to the arduino board (I am using a protoshield).

The button is pulled up with a 10k resistor which is pulled to ground when pressed. I have put a 0.47 uF cap on the input pin = pin 2 to also debounce the circuit a bit. In software I am using an interupt on the falling edge to detect button presses. The whole thing works nicely... Except...:

When the load ac input is switched on by the power company this is sometimes recognized as a button press! I am thinking that the suddon power spike induces a voltage in the 20 cm button wires which is recognized as a falling edge. How can I avoid this?

I am equiped with multimeter, oscilloscope, soldering... so I can try out any suggestions in detail.

Upvotes: 0

Views: 1135

Answers (2)

HixField
HixField

Reputation: 3796

I tried to solve this issue in hardware, but unfortunately failed. These are the options I tried, but that did NOT work

  1. used a shielded cable for the button
  2. implemented an XY denoise capacitor network on the AC of the load (input) like this one : http://www.conrad.be/ce/nl/product/450571/K042201052-Ontstoringscondensator-XY-Radiaal-bedraad-01-F-250-VAC-1-stuks?ref=searchDetail

In the end I implemented the following software solution:

The first time the button is pressed, it must be pressed 1 second before the button actually becomes active. This will never happen due to the AC turning on because this is a very brief spike. I programmed this into the arduino using interrupt to detect button press and then micro delay (inside the ISR) to check that after 1 seconds the button is still pressed.

After the initial 1 second button press, the button stays lively for 1 minute

Upvotes: 0

MasterTech
MasterTech

Reputation: 1

I am having a similar problem building a fuel injection flow bench. The button press starts a simulated engine run sequence that powers a relay. That relay then powers up to 6 injectors. What happens is as soon as I press the button the injectors closing induces a current and trips the whole system to start over again. The solution I've found that worked was using a battery to supply voltage to the injectors as opposed to the power supply itself. This isolates the arduino supply from the injector supply via my relay. The problem is of course now I need to keep the battery charged. I'm looking for a more elegant solution.

Upvotes: 0

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