Push button Delay Circuit

[avc4eva]

Hi all,

I have a question regarding a circuit i need to design:

I want to able to use a simple on/off momentary switch which when held for say 3-5 seconds interfaces with GPIO of MCU and turns on/off MCU (similar to the functionality of a smartphone when turning on/off).

I was thinking i would need some kind of LC circuit, the simpler the better, but should have consistent timing.

Or if anyone has any other suggestion to implement something similar to the of found in smartphones that would be great.

Andrea.

[exapod]

If the sleep current of the MCU is not too high you can use a GPIO with an interrupt that wakes up the MCU directly.

[avc4eva]

If the sleep current of the MCU is not too high you can use a GPIO with an interrupt that wakes up the MCU directly.

Yes this is the idea, however i want that typical 3-5s hold delay from smartphones to place into off/sleep.

[exapod]

You can do that in software with timers or rtc if you have one.

[avc4eva]

You can do that in software with timers or rtc if you have one.

True, however if the device is off/sleep that is difficult.

[exapod]

The first interrupt from the button wakes up the mcu, you set the rtc/timers for a 5s interrupt and go to sleep.
At this time if the user releases the button another interrupt is fired, the mcu wakes up you cancel the 5s interrupt and go to sleep.
If the user doesn't release the button the 5s interrupt wakes up the mcu and you are "on".

[avc4eva]

The first interrupt from the button wakes up the mcu, you set the rtc/timers for a 5s interrupt and go to sleep.
At this time if the user releases the button another interrupt is fired, the mcu wakes up you cancel the 5s interrupt and go to sleep.
If the user doesn't release the button the 5s interrupt wakes up the mcu and you are "on".

Ah great idea, thanks for that help!

Andrea