3 replies to this topic

[Christopher Gilmore]

Below is a simple example of the issue I am seeing. This program is supposed to call the DoorBellPort_OnInterrupt method ONLY when GPIO_PIN_D7 changes from low to high or high to low. What I am experiencing, is that everytime it switches.....the method is called multiple times (sometimes the board actually runs out of memory). I discovered this by setting a break point in the method itself. I manually switch the connection to pin 7 between the 3.3V and Gnd pins on the Netduino Plus to ensure that my input is not in fact switching quickly. public static void Main() { InterruptPort DoorBellPort = new InterruptPort(Pins.GPIO_PIN_D7, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth); DoorBellPort.OnInterrupt += new NativeEventHandler(DoorBellPort_OnInterrupt); Thread.Sleep(Timeout.Infinite); } static void DoorBellPort_OnInterrupt(uint data1, uint data2, DateTime time) { return; //Breakpoint here. Called multiple times per edge?? } Everytime the method is called, I do see that the data2 variable switches between 1 and 0 each time. What I dont understand is how this is even possible???

[Fred]

Physical switches bounce a lot when pressed. There's a glitch filter option that helps a bit, but you may need to add some debounce circuitry. By the way, you're not the same Chris Gilmour I used to kitesurf with are you?

[Chris Walker]

Christopher, If you connect D7 to GND and then start your app, how many times is the event called? Chris

[Christopher Gilmore]

Yeah.... Fred's suggestion worked (glitch filter = true and adding a debouncing circuit). I did a quick google on debouncing circuit and saw some examples. The problem ended up being fixed by putting a 1uF capacitor between the input to the netduino and ground. Below shows an example of how i added a capacitor C1. Also, R1 = 10Kohms. http://www.ikalogic....ng/debounce.jpg After that, the interupt only got called once for each edge. Thanks for the help! I've never been kitesurfing....