Arduino Nano Help / Final Stage of a Project

[Roowilliams]

Hello, will anyone be around the space tomorrow daytime, Saturday or Sunday to lend me a hand? I am getting one of my uni projects ready for my degree show and previously had wired up a basic model of what I have built with an outboard Arduino Uno to demonstrate some of the features, video here:

http://www.youtube.com/watch?feature=player_embedded&v=cDgqAymzotg 

For the degree show I am trying to make the complete concept. I have a chassis which holds:

1. 1 vibration motor
2. edgewise meters x 2
3. RGB LED x 2 wired in series (to illuminate the edgewise meters)
4. a servo (which raises and lowers the chassis)
5. IR distance sensor
6. Arduino Nano v3.0 to control it all

I am aiming to power it from USB if possible but if not will explore ways to add additional power to it - anticipating things like this is above my electrical knowledge so that's why I would love to have someone lend a hand, even just to watch over me and help me out while I put it together.

Everything is in place, I just need to connect the dots and write some simple code to demo things at the show!

Snacks, beers and comedy in the form of noob mistakes and delusional expectations will be supplied.

Cheers

- Roo

[Filthy hipster scum]

hey, this wont work on a Nano, in the slightest. you gonna have power issues and noise problems too. Let alone not enough pins

[Roowilliams]

Destroy me why don't ya!

Only had a quick read and it seems I can bring external power into the Nano... surely enough pins?

Not encountered noise probs before, shielding?

[Evan Davey]

Like everything, With extra circuitry it should be possible on a nano
but it won't work out of the box.

I presume the noise reference relates to back emf from the vibration
motor http://en.wikipedia.org/wiki/Counter-electromotive_force - you
can protect against this using a diode - see
http://gizmolab.pbworks.com/w/page/5686102/Arduino%20Tutorial%203%3A%20Motor.

That circuit shows how to use a transistor to allow the use of a
higher power supply / current for the motors.

I haven't worked with edgewise sensors before but presuming they will
require a lot more current than the nano can provide (which is
something like 40ma) - so again probably need to be driven by a
transistor at a minimum (also bare in mind these are analog not
digital devices).

Pin count will depend on the exact hardware you have chosen e.g.: the
protocol used by the IR sensor could require more than one pin

On Jun 7, 1:04 pm, Roowilliams <roowilli...@googlemail.com> wrote:
> Destroy me why don't ya!
>
> Only had a quick read and it seems I can bring external power into the
> Nano... surely enough pins?
>

> <http://cdn1.shopium.ua/d/arduino/uploads/nano-pinout.jpg>

>
> Not encountered noise probs before, shielding?
>
>
>
>
>
>
>
> On Thursday, 7 June 2012 12:53:21 UTC+1, Filthy hipster scum wrote:
>
> > hey, this wont work on a Nano, in the slightest. you gonna have power
> > issues and noise problems too. Let alone not enough pins
>
> > On Thursday, June 7, 2012 12:40:18 PM UTC+1, Roowilliams wrote:
>
> >> Hello, will anyone be around the space tomorrow daytime, Saturday or
> >> Sunday to lend me a hand? I am getting one of my uni projects ready for my
> >> degree show and previously had wired up a basic model of what I have built
> >> with an outboard Arduino Uno to demonstrate some of the features, video
> >> here:
>
> >>http://www.youtube.com/watch?feature=player_embedded&v=cDgqAymzotg
>
> >> For the degree show I am trying to make the complete concept. I have a
> >> chassis which holds:
>

> >>    1. 1 vibration motor
> >>    2. edgewise meters x 2
> >>    3. RGB LED x 2 wired in series (to illuminate the edgewise meters)
> >>    4. a servo (which raises and lowers the chassis)
> >>    5. IR distance sensor
> >>    6. Arduino Nano v3.0 to control it all

>
> >> I am aiming to power it from USB if possible but if not will explore ways
> >> to add additional power to it - anticipating things like this is above my
> >> electrical knowledge so that's why I would love to have someone lend a
> >> hand, even just to watch over me and help me out while I put it together.
>

> >> <http://distilleryimage8.instagram.com/b02da3c4b08f11e1b2fe1231380205b...>

[Simon Howes]

One chip I heartily recommend to many newbie microcontroller developers is the uln2803. Google it. Basically it takes 8 inputs from your uController on the one side and on the other side of the chip (directly opposite the input pin) it provides high current! Only thing to wrap your head around is that it sinks current not sources it. that means it provides - not +. So you connect your load on one side to + and the other pin to the channel on the chip. And this means you can run loads at psu voltage rather than ucontroller voltage. Ie: you're not limited to 3.3 or 5V as you can has 12v

It can provide about 500mA/channel and does up to about 16V or so if I recall, and it has support for a common diode in those cases where you're powering motors/relays/solenoids where you'll get backcurrent when they turn off.

Good little useful chip with a really cool kinda pnp design :)

[Andrew Williams]

Thanks for the info Evan, nice to have people on the list that make ideas bigger, not just smaller ;)

FYI an almost empty AA battery sends the edgewise meter needles to the top of their range with a force strong enough to give a audible tap (and make you think you broke something) so I'm hoping it shouldn't be a problem. I have seen them controlled with PWM before via Arduino to give a ticking down effect.

The vibration motor is only going to work sporadically to give a signal, and it is tiny so again. hoping this wont be much of a problem, but I can always pop a diode in if necessary as per your suggestion.

The IR sensor has three wires, one goes to an analog pin then +5 and gnd.

I will do a proper pin count later on and see if it all adds up. If all else fails with formally arranging stuff I might just turn up at the space and start working on it, hopefully I can find help as I need.

Thanks again

3D & Graphic, Illustration & Photography

http://www.roowilliams.com

[Andrew Williams]

Cheers Simon, will bear this in mind and look into it for future stuff.

As you might've guessed, the deadline is close (show starts on 14th) and I have been using Arduino all along so I WILL make it work somehow. Plus I taught myself a bit of Processing over the Easter holidays and want to make use of that.

Cheers!

3D & Graphic, Illustration & Photography

http://www.roowilliams.com

[Adrian Godwin]

On Thu, Jun 7, 2012 at 2:44 PM, Andrew Williams <r...@roowilliams.com> wrote:

Thanks for the info Evan, nice to have people on the list that make ideas bigger, not just smaller ;)

FYI an almost empty AA battery sends the edgewise meter needles to the top of their range with a force strong enough to give a audible tap (and make you think you broke something) so I'm hoping it shouldn't be a problem. I have seen them controlled with PWM before via Arduino to give a ticking down effect.

Chances are they're 100uA or 1mA. If you drive them from an arduino PWM output then you want to arrange 100% to be full scale. Try a series resistor of 4k7 (for 1mA) or 47k (for 100uA) from 5v and see if they behave a bit more gently. If you have exact specs for them (current and resistance) then you can make a more accurate guess. Excess current WILL break them - either mechanically or electrically - so don't abuse them.

full-scale current = supply voltage / (internal resistance + series resistor)

 

The vibration motor is only going to work sporadically to give a signal, and it is tiny so again. hoping this wont be much of a problem, but I can always pop a diode in if necessary as per your suggestion.

Put the diode in anyway. If you drive an inductive load it won't just generate noise, it can generate quite high voltages which will kill at least that pin if not the whole micro. the ULN2803 already has the diode internally, but note that all the loads it controls must have a common positive - you can't switch some to +5v and others to +12 or some of the diodes will be wrongly connected.