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Author Topic: Arduino practicalities  (Read 4028 times)

Norman Castle

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Arduino practicalities
« on: December 27, 2015, 08:20:12 PM »

Arduino newbie here wondering ...

1  How are you guys actually mounting the PCB in your model?

2  How are you powering it - off your propulsion batteries or from a separate supply (AA cells/PP3)?

3  At the moment I have 3 connections to the PCB via 22AWG hookup wire pushed into the pin headers.  These join the servo and RX leads at a triple screw-type miniature connector strip, which isn't exactly an elegant way of doing things.  Is there a better way of doing the "wiring harness"?   
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barriew

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Re: Arduino practicalities
« Reply #1 on: December 27, 2015, 09:01:10 PM »

Norman


At the moment I am not planning to use my Arduino in a model, although that is an option in the future. If I do, I will use either a Nano or the even smaller version (Micro?). If I need other components I will mount the whole lot on strip board, and put it in a case. As for power I will use a 5 volt regulator to take the power off the motor battery.


What are you using your Arduino for?


Barrie
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richald

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Re: Arduino practicalities
« Reply #2 on: December 27, 2015, 09:33:37 PM »

Re : Arduino power supplies I quote from the Arduino Website for the Nano board . . .

Input Voltage (recommended)    7-12 V
Input Voltage (limits)                 6-20 V


So you shouldn't have any problems powering it from any of the commonly used
model boat power supplies SLA (possibly), NiCd, NiMh, Lipo 2s and 3s
 
I haven't checked, but I would expect the Uno and the Mega boards to have the
same PSU requirements.

I use some very neat LED Driver PSUs on my mains powered stuff.

http://www.ebay.co.uk/itm/LED-Driver-Power-Supply-Transformer-240V-DC-12V-/230689466731

Richard
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C-3PO

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Re: Arduino practicalities
« Reply #3 on: December 27, 2015, 10:17:16 PM »

I would recommend that the Arduino has it's own supply completely seperate from that used for any other kit used in the boat esc, servos etc. to stop any "funnies" (emf/brown outs etc) with the board. I am aware that some people had a frustrating journey before identifying this rule!  My normal solution 4xAA batteries just because it's easy and cheap. Note if the supply to the Arduino is less than 7volts and 5 volt logic circuits  are important to your system be aware that those pins may not (won't) reach 5 volts.
 

C-3PO
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tsenecal

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Re: Arduino practicalities
« Reply #4 on: December 28, 2015, 12:46:01 AM »

power:
i actually power my arduinos from the receiver, as if they were servos.  5v from the receiver going to the 5v pin on the arduino.


mounting:
i build a tray of ABS sheet plastic, .040" slightly larger than the arduino, so that i can have a 5v rail and a GND rail running alongside the arduino PCB, and once every other device is soldered to the arduino, the entire object is wrapped in heat-shrink tubing.  then that is attached to the submarine's tech rack using servo tape.
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Norman Castle

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Re: Arduino practicalities
« Reply #5 on: December 28, 2015, 08:22:08 AM »

What are you using your Arduino for?
  Right now it's just for running an apparently-random sequence of turret rotations on the model I'm currently building, but there are certainly other possibilities too ...

... a 5v rail and a GND rail running alongside the arduino PCB ...
Ahah!  Now that's one option I need to think about.  Thank you!

I'm completely new to this Arduino lark, and AFAIC there are two problems with it (or at the least with the Uno).  Run-of-the-mill PCB mounting solutions seem to be out due to the M3-clearance mounting holes being fairly hard up against components, so at the moment it's looking a lot like Velcro for this one.  And because of the need to connect one pin on it to the servo, one to the RX and one to the ground of both servo and RX, I can't yet see any way of actually doing the complete installation in the model without it looking like a lash-up!
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g6swj

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Re: Arduino practicalities
« Reply #6 on: December 28, 2015, 08:51:41 AM »

The Arduino official view https://www.arduino.cc/en/Main/arduinoBoardUno
Quote
-5V.This pin outputs a regulated 5V from the regulator on the board
The board can be supplied with power either from the:
  • DC power jack (7 - 12V)
  • the USB connector (5V),
  • or the VIN pin of the board (7-12V)

Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.

So if you want to take 5v straight to the board you should consider using the VIN pin. If you decide to use the RX power as a supply to the Arduino what voltage does it actually supply and does it suffer from electrical noise or voltage drops?

Each setup is unique (different current demands, different electrical circuits/components etc.) and whilst "short cuts" might work with one setup it may cause havoc with another. How many boats don't use fuses in the power line which is OK until it's not!

g6swj
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g6swj

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Re: Arduino practicalities
« Reply #7 on: December 28, 2015, 09:32:43 AM »

Curiosity killed the cat

I have just connected 2 servos to a receiver and monitored the DC 4.8v supply on an oscilloscope and there is definitely voltage drop/noise when the servos are working. If I can work out how to screen capture my scope I'll post image here.

So I have confirmed in my own mind which route I will take every time - it's just not worth the risk!

Quote
Use a clean separate supply to Arduino board without exception

caveat emptor

g6swj



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barriew

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Re: Arduino practicalities
« Reply #8 on: December 28, 2015, 09:49:10 AM »

And because of the need to connect one pin on it to the servo, one to the RX and one to the ground of both servo and RX, I can't yet see any way of actually doing the complete installation in the model without it looking like a lash-up!


Norman - take a look at a Nano - they have solder pads for connection instead of the headers which makes it easier to connect your Rx and servo. They are not very expensive and you keep the Uno as a development machine.


Barrie
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afb

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Re: Arduino practicalities
« Reply #9 on: December 28, 2015, 09:56:29 AM »

Arduino Mounting - as I need additional components to support the Arduino Nano in this engine sound unit, I used a double-decker arrangement with the PCB below carrying the power MOSFET that drives the speaker directly, the power and speaker terminal blocks, the neutral/run LED, the set-up push-button switch and the RX (throttle) input.
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g6swj

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Re: Arduino practicalities
« Reply #10 on: December 28, 2015, 10:07:20 AM »

Hello 007,

As a man that knows lots about this type of stuff should we be concerned how we power a bare board Arduino?

Clearly if non critical use (gun turret movement etc)  then it probably doesn't matter using RX supply etc  but when controlling and ESC or Mixer it could be more significant. My point is if you start out the right way, and then get into different applications of the Arduino, the power issue won't come back to haunt you.

g6swj
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afb

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Re: Arduino practicalities
« Reply #11 on: December 28, 2015, 10:25:37 AM »

Hi Jonathan - still dipping my toe in the water with the Arduino, but my PICAXE mixer and ESC experience suggests they are very resilient to operating from the RX supply. The Arduino sound unit shown has a jumperable link (obscured by my forefinger) that can connect the speaker battery supply to the Arduino's Vin pad and the resultant 5v appearing on the throttle connector can go on to power the RX.

HOWEVER, connecting a servo to this as well would be asking for trouble by overloading the 5v regulator on the Arduino - this unit was made for a narrow gauge garden railway locomotive so not a servo in sight!

Obviously, I don't jumper the link if the ESC has a BEC.

Like me, keep on taking the learning pills . . . . . . .
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richald

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Re: Arduino practicalities
« Reply #12 on: December 28, 2015, 11:13:02 AM »


Norman - take a look at a Nano - they have solder pads for connection instead of the headers which makes it easier to connect your Rx and servo. They are not very expensive and you keep the Uno as a development machine.
Barrie

I have purchased some of these - should be OK but I haven't used any of them yet.

http://www.banggood.com/ATmega328P-Nano-V3-Controller-Board-Compatible-Arduino-p-940937.html

For mouning I use a strip of female SIL socket connectors either glued to small block of wood or soldered to a chunk of
veroboard - easy then to connect to your own wiring.

http://www.banggood.com/10Pcs-40-Pin-2_54mm-Male-Female-SIL-Socket-Row-Strip-PCB-Connector-p-953436.html

Richard
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Norman Castle

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Re: Arduino practicalities
« Reply #13 on: December 28, 2015, 01:15:40 PM »

For mouning I use a strip of female SIL socket connectors either glued to small block of wood or soldered to a chunk of veroboard - easy then to connect to your own wiring.

Cheers Richard, that seems to be a sensible way forward  :-)

I'm still scratching a kosher way of mounting the PCB in the hull though, so this looks like being yet another use for Velcro ...  %)
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