Is it possible to run more than one pin to an interrupt for sleep/wake purposes?

[drock1985]

Hi,

I have a 4x4 keypad working as a scene controller with MySensors. Before I decided to run hard power wire to each point I want to run a keypad, I would like to look at going battery powered. I know I can't run the Nano and the radio continuously for long, so I need to use a sleep function. The only problem with that of course is, the 8 pins I am using for the keypad aren't all interrupts.

Just wondering if there is any way around this?

[Sparkman]

@drock1985 Here's one method: http://www.gammon.com.au/forum/?id=11091.

Cheers
Al

[Ivan Z]

I hav 6 buttons
https://www.openhardware.io/view/26/Battery-button-sensor

[drock1985]

@Ivan-Z

Yes, I have seen your project :) I love it, and would love to incorporate it for my scene controllers; just presently I need to have access to 8 digital pins for it to work right. I'm working on a way to get itdown to 1 analog pin, but that doesn't help my interrupt problem at all.

@Sparkman

I'll look into this more, thank you.

[drock1985]

@Ivan-Z

Just looked closer at your design; you already have the interrupt set up on D2 don't you? :)

If that's the case; out of curiosity, is there room for a couple of analog pins in the design that could work as digital?

[Ivan Z]

This is only a project (In progress).
Be sure to add
But I think that it only increase consumption

[AWI]

@drock1985 A quick drawing of a circuit which enables you to use only one interrupt...

When any of the keys is pressed you get an interrupt (FALLING) on D2. From that moment on you can poll the keyboard. Any of the digital and analog pins can be used for that purpose (except those in use by the radio..)

(you need to change the resistor values on the left side of the drawing to 10Mohm)

[drock1985]

@AWI

Thanks AWI, i'll prototype something out a bit later and give it a shot.

[karl261]

@AWI I have such a keypad 4x4 and I would like to use it with the famous my slim aa battery node. I think I understand your drawing. What I don't understand is what diodes do I need to use? I mean what type?

Also, if I was to include a green and red diode, or a bi-colour diode, what specifications would they need to have? Any links to the usual "shops"?

Thanks!

[AWI]

@karl261 You can use almost any diode, e.g a 1Nxxxx type

And for bi-color LED's many choices , just include a resistor (around 300ohm) in series.

[Nca78]

Maybe a stupid question but why don't you change your keypad with a capacitive touch keypad ?
I have one of these and it's convenient, low power usage in sleep mode and one interrupt pin for keypress on any of the keys. Just make sure you only connect it to 3.3V, for power AND logic.
http://www.aliexpress.com/item/MPR121-Capacitive-Touch-Keypad-Shield-module-sensitive-key-keyboard/32642505921.html

[karl261]

@Nca78 yes, you are absolutely right. Maybe that is what I'll do. Sound much easier. Thanks for the link, I check it out!

[karl261]

But in the end, I prefer the keypad I have. It looks nice.

Maybe this is the simplest solution? It turns the keypad into i2c:
https://www.hackster.io/venkatesh_rao/i2c-keypad-73a012

[karl261]

Wow, this is so cool, the pcf8574 port expander works out of the box. If now even the interrupt works...

[karl261]

Ok, in the end I am stuck. So, I got the keypad working, no problem. But I cannot get it to trigger an interrupt. The PCF8574 has an interrupt pin, but it seems this does not work with this keypad. Or at least I could not figure out how to. So, my keypad speaks I2C now, but still has no interrupt capabilites.

Can anyone advise?

If not I will need to build the circuit from @AWI. Btw, in that circuit, Are ALL resistors 10 MOhm?

Or are R1-4 1 MOhm?

[karl261]

Few crazy solutions:

1. I put in an on / off switch. So before I type, I switch the whole thing on, wait until it registers with the gw, and then here we go. And then off. No need to sleep and wait for interrupts.

2. I can install a button device. So, the thing is sleeping, I press the button, the thing wakes up for 30 secs, that gives me time to type and send, and back it goes to sleep.

3. I have a 4x4 keypad. So, I don't need the ABCD. I could connect the ABCD in a way, that it acts like button device, so I can trigger the interrupt with ABCD, then type my number, and then it goes back to sleep.

[AWI]

@karl261 these options seem all very odd to me. I2c should work, did you activate a pull-up for the interrupt pin? Can you post your sketch and hardware connections?

[karl261]

@AWI Thanks for trying to help! Just a quick question first: Do I draw the circuit by hand or is there a good cheap (free) way to do it on the PC? Or tablet?

I think it is how the pcf8574 is designed. I detect no change on the interrupt pin. But yes, maybe my wiring is not good.

[mfalkvidd]

@karl261 by hand is quick and easy. I like to use Fritzing, which is a free tool.

[AWI]

@karl261 As @mfalkvidd said. just make an simple hand drawing on how you connected the pfc8574 and the int pin. The rest is obvious. The pcf8574 can generate an interrupt on any change of the input pins.