Two leds based on one interrupt line

[Manoj Hiwarkar]

Dear sir,

I am using STM32F769NI microcontroller. I want to glow to different Leds on one external interrupt line i.e. Led1 on rising edge and Led2 on falling edge. Can you please suggest me the solution.

Regards,

Manoj

[waclawek.jan]

You can set interrupt on both edges in EXTI, and by reading the current state of pin from GPIO_IDR you can determine which was the last edge.

JW

[Manoj Hiwarkar]

Ok. But in my case the level 0 appears in two cases first when logic 0 is applied and second when the line is disconnected. So what shall I do in this situation?

[waclawek.jan]

What is "line disconnected"? Elaborate.

JW

[Manoj Hiwarkar]

@Community member​  line disconnected means open.

[LCE]

Use a pull-up resistor.

[Manoj Hiwarkar]

So the last state will be always '1' if I use the pull up resistor.

[waclawek.jan]

There is no magic way to distinguish 3 states.

In software, periodically switch between pullup and pulldown, and sample input. If input follows the pullup/pulldown pattern, it's open; otherwise it's connected and you know its polarity.

JW