Gimzo 2 custom On/Off button?

Check out this post where I added an external power and reset button: http://www.element14.com/community/community/designcenter/single-board-computers/gizmo2/blog/2015/01/28/gizmo2-adding-external-pwr-and-rst-buttons

Oh wow, so much great tutorials I'm having hard time finding

So you didn't use a resistor?

Is there any requirement for what button can be used. All I know is buttons have a maximum current rating, this shows how little my electronics knowledge is. But it's going to be fun programming the Gizmo after I get this figured out.

PS. Is that a 3d printed enclosure? That's another hobby of mine.

Frankly I suppose this can represent a problem but to be sure in this particular case (it is the first time I do this on a Gizmo2) I should test it. My suggestion is to add the resistor and ignore the debouncing circuit. This can be done in minutes with a breadboard. It is probable that this works as I suppose.

The debouncing effect is almost common with push buttons and can be solved - as shown in the page I got you before - via software or hardware. In this case it is not possible to solve it by software so a small circuit should be done. For more detail on how the debouncing should be implemented and why this occur, take a look to the following pdf: http://www.eng.utah.edu/~cs5780/debouncing.pdf

So im confused, you think debouncing will be an issue here, or the opposite?

Hi Mark,

Enrico is suggesting try it with a resistor, see if it works for you.

If you observe some behavior that is undesirable (e.g. having to hold the button pressed for a long time) then it can be considered further and you then may need a more complex circuit.

His linked article is extensive, and provides much detail on how different debouncing circuitry works.

Whether you actually need delays, debouncing, etc., can be answered in detail either by Gizmosphere (since they designed the board), or a detailed examination of the circuit and the power management IC user guide (which would require some time to investigate). An alternative approach (as suggested by Enrico) is to just try it, observe the results and see if it fits your required button-press behavior.

Thanks shabaz

Sorry that I didn't get what you meant the first time. Thanks.

EDIT: Oh wow, I confused the original post by Frederick Vandenbosch with Enrico Miglino because both of you had similar minions avatar, thats why I felt I was getting contradicting info from you.

Sorry for being a bit too cautious.

The power on/off pins are these, right (highlighted in green)?:

And does the size of the switch matter? (different current from different resistance or something?)

And hopefully last question: if I want Gizmo to autostart, just use a simple jumper with resistor for these two pins?

The first answer is yes.

The second answer is no. The pin simply send a signal based on the pull down as it is pressed and connects the high signal to ground then this input signal tells to the boot firmware to start the boot process, load the bios etc.

To have the system autostart you should know how and modify this internal part of the firmware. In theory it is possible, just with the programmer and the sources of this part of the Gizmo2 project. As the entire device is open source you should not have difficult to find the information and software that is needed. But what is the reason you need the system autostart? And autostart what does ti means for you? Something should happen to make the system to start, correct? What event ?

Enrico

Was the first answer also the answer to "does the size of the switch matter"?

Okay, here's the reason I was thinking of having autostart for the Gizmo:

1) The device is something like a light fixture consisting of 3 individual devices in one case:

1. a tiny video projector

2. Gizmo 2, which generates graphics and sends to the video projector

3. an Arduino (Nano), for having buttons to choose between media files stored in a USB stick and read by a program running on the Gizmo 2 and communicating with the Arduino via serial, as well as controlling a tiny shutter motor to block video projector beam in some instances.

So I need to turn on 3 individual devices, but want to have 1 button for that. It might be simple to create a circuit board for most of you to do this, but I don't have the skills.

Arduino boots and starts executing when Gizmo 2 does, if connected via USB. So no problem there.

Video projector is more complicated, it has a button you need to press and hold for 4 seconds for it to turn on. Sadly it can't autostart like the Arduino when power is applied.

Now, if Gizmo autostarted as well when I connected the (not stock) power supply, I could still have what I want ( 1 button for turning on (visibly on) the light fixture ) and pressing the turn on button would start the video projector, and everything else (Arduino and Gizmo) would be ready already.

But if autostarting Gizmo is not easy, I need some simple solution for powering both the Gizmo and video projector with one button.

One solution I have in my mind is having the power on button just start the Gizmo, and then emulate the 4 second button press by a DC-DC relay and the Arduino (soldering cables around the video projector's start button).

In my opinion you have the solution in your hands but you don't see it

Power on - Arduino starts

Then the first thing that Arduino should do one is power the projector, then power the Gizmo2 then Gizmo2 starts communication etc. etc.

How to? In both cases you need to connect the button that should be pulled to GND to one of the Arduino I/O and with a simple circuit based - for example - on a PN2222 transistor it is Arduino that do the job of powering on and off the systems.

To manage the long press on the projector, short press on the Gizmo2, long press on Gizmo2 for power-off all can be done (and must be) by the Arduino, that is just the board that - as it is a Micro Controller - has this role in your architecture.

The following link explain you very clear (with circuit) how to use and I/O digital pin on Arduino to simulate a push button switch using a PN2222 transistor: https://teachmetomake.wordpress.com/how-to-use-a-transistor-as-a-switch/

Enrico

If I dont find a right transistor on time, are there DC-DC relays which could be used for this?

If I dont find a right transistor on time, are there DC-DC relays which could be used for this?