Powering Arduino

[amesmich]

How would you power an arduino? I know its considered a custom circuit but do you power it. With a small fuse directly from the PD board, or can you tie it in with the 12v-5v- voltage converter? R43 says nothing else can be connected to the PD where the converter gets its power but they dont specify the low volt side of the converter. Any help is appreciated.

[Al Skierkiewicz]

Under the current rules, you can feed a custom circuit through a small breaker on the PD under R46 with a smaller fuse on the custom circuit. You may not use the power supplies on the PD for anything other than the cRio, radio and camera. A small three terminal regulator and a few components on a small, insulated, custom circuit is an appropriate method of supplying 5 volts to another custom circuit.

[yash101]

Under the current rules, you can feed a custom circuit through a small breaker on the PD under R46 with a smaller fuse on the custom circuit. You may not use the power supplies on the PD for anything other than the cRio, radio and camera. A small three terminal regulator and a few components on a small, insulated, custom circuit is an appropriate method of supplying 5 volts to another custom circuit.

Wait a minute, so you can't power a computer off the PDB regulators? (The 5v rail)

[Mike Bortfeldt]

For a low power device like an Arduino, you can also power it from the 5v on the digital sidecar (Digital I/O PWR).

[Chadfrom308]

Just power it directly from the PD. The arduino can take in 12v, just make sure you know that anything powered from the 'Vin' pin on the arduino is also going to be 12v and will fry whatever 5v electronics you hook up to it

[apalrd]

We used 6v from the servo power supply through Arduino's vin.

You can use the PD board 5v supply if you would like:
R36

All circuits, with the exceptions of those listed in R42 and R45, must connect to, and have power sourced solely by, a single protected 12VDC WAGO connector pair (i.e. the Load Terminals, as shown in Figure 4-11) or the 5VDC supply on the PD Board (as shown in Figure 4-12), not the M6 shanks.


You can't use the cRio or radio supply though.

[Joe Ross]

You may not use the power supplies on the PD for anything other than the cRio, radio and camera.

There are no restrictions on the pdb 5v supply (the "camera" supply ). In fact, its explicitly allowed for other uses by R36.

[otherguy]

We went with a 5v 3A regulator from CPT last year to power our Arduino and connected LED light strips.
This is the same company that makes the regulator for the wireless bridge.

http://www.current-logic.com/dcdc_converter_cpt_fulree.php


It's potted so no worries about shorts due to debris
Screw terminals for easy mounting
Cheap: You can find them on ebay for a few bucks


We didn't have any problems with it on/off season. This would certainly be overkill if all you needed to run was an arduino. If you need to drive other components as well off the supply though, it's a great option.

[steinra]

This is right along the same topic we were working on last night.

I know that the rules have specific restrictions for motor power and other devices having their own connect points to the PD.

What was not clear is a custom sensor circuit, multiple loads.

We want to accomplish the same thing the PD is doing for the cRIO. A DC to DC step up to 24v, 5A, bring back down to 5v, 5A to power the other systems. (LED strips need a lot of power as do several computing devices). May also need to pull 12V off the 24V step up.

This branch circuit would have LED lights, Arduino and let's say a Raspberry Pi or two, plus and USB devices hanging off them.

What is not clear to me is if each of those would require their own power, or can all of those be supplied by the same 5v supply off a single breaker / fuse on the PD?

I may need to frame it up as a GDC question, but want to make sure it is phrased in a way that we don't get the "can't speak to specific designs" answer.

Ultimately I am trying to figure out if I need multiple separate 24V step ups with their corresponding step downs for each device, or can I have a "sub" PD with separate fusing?

Thanks!

Randy

[amesmich]

Thanks for the replies. I think we may go with the "otherguy"s route. I dont want to start messing with the PD 5v supply and get called. I would rather branch out with my own circuit. Clean and confined.

[Al Skierkiewicz]

Randy,
Why are you going up to 24 volts to step back down to 12 or 5 volts?

[Thad House]

There are actually 3 places you can get a stable 5V supply off the robot. You can grab it off the PD, off the Sidecar, and off the Analog Breakout. I don't have the schematics in front of me right now, but I believe the Analog Breakout can source about 1A, which is defiantly enough to power an Arduino. Because most analog circuits won't source much, you should have alot of that power free.

[steinra]

Thank you for the question Al!

It is more for the 12v than the 5v, but to allow for the voltage drops in the battery supply side under heavy drive load (see supply drops to 9v/10v during heavy acceleration / motor use). Mainly to avoid brown out conditions for devices that need that stable higher voltage.

My understand as well for why they are stepping up the voltage in the PD for the devices connected there (cRIO, radio, camera). Voltage rail stability. I could be understanding incorrectly as well. (in looking at the schematic, this may be the case of me being off)

Now I see in the PD schematic that there is both a 24v, 12v step up and a 5v buck switching. The corresponding devices i think would step down to 5v and 3.3v.

Now it could be the cRIO only came in 24v, so that could be the reason as well, but would expect the step up would help with supply side stability.

Rethinking (or as the GPS says, recalculating). For the 5v supply I might be able to get away with the buck now that I think about it some more, and may be able to get away with the 12v step up only.

I really appreciate the question as it made me think more about it. Maybe we will just build these like the PD has and do multiple supplies (now to find the best way to SMD ::ouch:: )

I am not a EE, so may be WAY off here.

Thanks!

Randy

[otherguy]

Ultimately I am trying to figure out if I need multiple separate 24V step ups with their corresponding step downs for each device, or can I have a "sub" PD with separate fusing?

Consider all your separate custom circuits as one system, a black box. Power goes in, it does some stuff.

You can consider them multiple separate custom circuits, or as one single custom circuit.

That said, why are you stepping up to 24v then down to 12v and 5v?
It doesn't sound like you need 24v at all in your custom circuit. It sounds like 5v and "possibly" 12v.

You can get 12v directly off the PDB through a breaker. No rule violation there.
You can get 5V for a custom circuit from any of the places listed above in this thread.

If you have LED strips. Get a 12v to 5v regulator with a high enough current rating to feed your strip, and plug it in to the PDB...

Don't make it harder than it has to be.

[amesmich]

I have used these in many other projects to regulate 24vdc down to 12v for an arduino (among other things) and they work great. Yes you can give the arduino 24v and it will be ok but I dont like to stress the VR on the arduino that much.

http://www.amazon.com/RioRand-LM2596-Converter-1-23V-30V-Pcs-LM2596/dp/B008BHAOQO/ref=sr_1_2?ie=UTF8&qid=1389806412&sr=8-2&keywords=dc+to+dc+power+module

http://ecx.images-amazon.com/images/I/41oDKWEa9RL._SX425_.jpg

[SteveGarward]

We have used this module from Sparkfun for 12V->5V for our Arduino and LEDs..
https://www.sparkfun.com/products/9370

You need to calculate the value of an external resistor for your output voltage (check the datasheet), but it's easy to use and a high current rating. May need active cooling depending on the current you draw - it does get pretty warm with our LEDs.

[Joe Ross]

I don't have the schematics in front of me right now, but I believe the Analog Breakout can source about 1A, which is defiantly enough to power an Arduino. Because most analog circuits won't source much, you should have alot of that power free.

There are three versions of the Analog Breakout. The 2009 version can supply 3 amps and uses a switching regulator. The 2010-2013 version uses a linear regulator and can supply 0.25 amps continuously. The 2014 version also uses a linear regulator and can supply 0.25 amps continuously (and doesn't require the battery voltage jumper to comply with R70).

[steinra]

I have used these in many other projects to regulate 24vdc down to 12v for an arduino (among other things) and they work great. Yes you can give the arduino 24v and it will be ok but I dont like to stress the VR on the arduino that much.

http://www.amazon.com/RioRand-LM2596-Converter-1-23V-30V-Pcs-LM2596/dp/B008BHAOQO/ref=sr_1_2?ie=UTF8&qid=1389806412&sr=8-2&keywords=dc+to+dc+power+module

http://ecx.images-amazon.com/images/I/41oDKWEa9RL._SX425_.jpg


Thanks for the link, I think we will give these a try.

Randy

[otherguy]

It is more for the 12v than the 5v, but to allow for the voltage drops in the battery supply side under heavy drive load (see supply drops to 9v/10v during heavy acceleration / motor use). Mainly to avoid brown out conditions for devices that need that stable higher voltage.

If you just need a regulated 12v supply, you can buy a single buck/boost supply that outputs 12v and has a wide input range. Then there's no need chain a bunch of regulators together. I don't know what your current requirements are, that will be driving your purchase.

This one on amazon (http://www.amazon.com/DROK-Converter-Automatic-0-5-30V12V-Regulator/dp/B00CCL3UP2/ref=sr_1_10?ie=UTF8&qid=1389812484&sr=8-10&keywords=12+buck%2Fboost) says it can output 2A @ 12V with no heatsink. Could wire directly into the PDB connections off a breaker.

These things all come out of china, so if you can deal with waiting a few weeks for shipping, you can check ebay for better prices and a wider array of parts/suppliers to choose from.

[Al Skierkiewicz]

Randy,
The power supplies on the PD are designed with brownout in mind. They continue to put out down to at least 5 volts but typical is 4.5 volts. The cRio is only available in a 24 volt version as this is a standard industrial power supply. It actually has a wide voltage rating, 19-28 v as I remember.

[rmiko]

Hi,
Does anyone know if we can use a second KoP 12V/5V DC-DC converter off a normal port on the pdb to power the arduino?
Are there any rules against using a second one of the KoP DC-DC converters?

Thanks

[Al Skierkiewicz]

There are no rules to prevent this use.

[fsgond]

When we used Raspberry Pi's last year we bought a second power supply that is used for the wireless router. It gives a solid 5v under extreme conditions, hence the reason it is required for the radio. Of course you would need to power it off of the PD through a 20A breaker since it is a custom circuit. It worked great for us, but did raise some questions since there were 2 and 1 of them was plugged in to a 20A breaker. Just know the rules and be able to explain why you did it the way you did it and the inspectors will pass it.

[Michael Hill]

When we used Raspberry Pi's last year we bought a second power supply that is used for the wireless router. It gives a solid 5v under extreme conditions, hence the reason it is required for the radio. Of course you would need to power it off of the PD through a 20A breaker since it is a custom circuit. It worked great for us, but did raise some questions since there were 2 and 1 of them was plugged in to a 20A breaker. Just know the rules and be able to explain why you did it the way you did it and the inspectors will pass it.

You don't HAVE to use a 20A breaker for a custom circuit. R46 states that you can use UP to a 40A breaker for custom circuits. In fact, a 5A breaker would be just fine.