3 replies to this topic

[sebastianpatten]

Why is my code throwing an ArgumentException when I use the following?

InterruptPort input = new InterruptPort(Pins.GPIO_PIN_D0, true, Port.ResistorMode.PullDown, Port.InterruptMode.InterruptEdgeLow);

It doesnt like the pulldown for some reason.
Thanks!

[CW2]

It doesnt like the pulldown for some reason.

Unfortunately, the Netduino microcontroller does not have pull-down resistors, you have to use external ones.

[Chris Walker]

As CW2 mentioned... some microcontroller have integrated pull-down resistors; others have pull-up resistors; others may have both or neither. The SAM7X microcontroller on the Netduino has pull-ups. If you need pull-down resistors, just follow CW2's advice and add an external pull-down. Chris

[Arbiter]

As I recall the point of a pull-up resistor is to stop a signal line from floating by tying it to (int this case) 3.3V through a large resistance, such that a switch shorting the pin to earth will pull it low but otherwise it will be pulled to high. Is this the behaviour we can expect from the Netduino: inputs report high unless shorted to ground? "ArgumentException" is an atrocious way to report a not-supported condition. Especially when there is a NotSupportedException. You could also say something useful like "Netduino hardware does not support PullDown mode." Is there any literature on using the Netduino other than this forum and that IoT book?