Keeping UNO pinouts clear while connecting nRF24L01

Most postings recommend Vcc and Gnd on the nRF24L01 to 3.3V and GND along the edge of the Arduino UNO board.

In the interests of keeping as many UNO pins as possible free, is it safe to connect the NRF24L01 pins to Vcc and Gnd at the ICSP pins at the end of the board (opposite end from power input)?

Hi Rick,

2 things:

  • nRF24L01 power MUST be 3.3V.

  • GND is not critical, however the nRF24L01 modules NEED better bypass capacitors on 3.3V to Gnd AT the module. See the info HERE:

The limited Vcc , 3.3V and Gnd pins on the UNO was a major motivation for the UNO derivative design you can see HERE: which was a collaboration with a good guy in China. I have sold 4 or 5 Thousand of these. See ALL THE PINS… Yay!

I like the idea of all those extra ports, but it doesn't solve the original problem - that of getting power to the nRF24L01 without blocking the only available 3.3 V port. The Vcc pin (pin 1) of the ICSP pinset is 5 V (I think) and all the extra power ports on the RoboRed PCB are 5 V. Still, you would only be using one nRF24L01 on any one UNO, wouldn't you! :wink:

Getting on to getting quality 3.3 V from a UNO, the advice from the website is
"Connect a 3.3 uF to 10 uF (MicroFarad) capacitor directly on the module from +3.3V to Gnd (Watch + and - !) [Some users say 10 uF in parallel with 0.1uF is best] This is especially important if you are connecting the module with jumper wires. Or you are using the regular Arduino UNO which provides only 50 mA at 3.3V.".

Dare this terrified newbie ask for more illustrative information on how this is done. I am not all that confident about my understanding of 10 uF in parallel with 0.1uF , and even less confident about Watch + and - !

Just a photo would suffice and would be much appreciated.

I just soldered a 10 uF capacitor between the wires. Paid no attention to +ve and -ve. What’s parallel? Figured that if it blew up I’d just have to get new ones :smiling_imp: Dunno what that is but it certainly improved things.

160828-Arduino with Capacitor.jpg

vagulus:
I just soldered a 10 uF capacitor between the wires. Paid no attention to +ve and -ve.

That's smart. You'll go far.

What's parallel?

  1. (of lines, planes, or surfaces) side by side and having the same distance continuously between them.?

parallel capacitors

The arduino (and any other microcontroller dev board with only one power pin available) is meant to be used with breadboard (or other means of easily connecting things - I use protoboard connected with Dupont line). As you've discovered, one power pin is never enough.

When I do a dev board design, I always put a bunch of vcc and gnd pins so you can use it with just breakout boards and Dupont line without having to come up with a way to split the power) - but this doesn't seem to be commonly done.

Thanks DrAzzy

I’ll do just that!

but it doesn't solve the original problem - that of getting power to the nRF24L01 without blocking the only available 3.3 V port.

The 3.3V power pin on the UNO was very stupid idea, IMO. The power limitations are severe:
DC Current for 3.3V Pin 50 mA

The peak power for the nRD24L01 is stated in online literature as reaching 115mA.

The weird thing about semiconductors and power dissipation is that failure may or may not occur; because "peak" may not cause an immediate fault in the semiconductor. But, it is not wise to design by taking such a chance.

Just buy an under $1 DC-DC bulk converter and use it to derive the 3.3V from either the external 5V powering the arduino or from the power supply that provides the arduino barrel jack.

OldSteve reckoned I’ll go far. That’s fair. Plenty of people tell me it should be soon. :roll_eyes: Still, it turns out that paying attention to +ve and -ve wasn’t such a bad idea.

Experts know things that newbies like me don’t. That’s why they are considered experts. I have discovered that these capacitor thingies I bought have a +ve leg and a -ve leg (that’s right - discovered - I did not know this from birth as some folk expect :wink: ) and that keeping + to + and - to - gives me a parallel connection. One of my two capacitor thingies was the wrong way round (50-50 I guess you’d call that). Fixing that reduced the error rate to 3% at 20 m - a substantial gain.

Please folks, don’t expect newbies to know anything. That’s why were are considered newbies! :blush:

vagulus:
<…>
Please folks, don’t expect newbies to know anything. That’s why were are considered newbies! :blush:

After 30+ posts, your newbie status is getting a bit long-in-the-tooth. There are newbies that have just started Arduino that come from other engineering fields and then there are newbies that are starting at the ground floor. It is very difficult to write for both groups which is why it is so very important that newbies of both categories read the forum stickies and try to provide details and code examples, etc.

That being said, many us older crowd started electronics early in our teens with Ham radio or electronic kits from Radio Shack (Or Lafayette or Allied/Knight Kit or Heath Kit, etc.) In these basic electronic projects one would build shortwave radios or even test equipment such as VOM and RF/Audio Oscillators. I’m looking at a VOM built in 1967 that still functions although it takes the tube circuit several minutes to stop drifting. Tubes… yes, those things that get hot and utilize high voltages! :o

Much of the old magazine articles from Ham radio, Popular Electronics, Radio Electronics are still available over the Internet. There are also some good forums on basic electronic circuits, one is http://www.hobbyprojects.com/ but there are many others. Such projects get you familiar with resistors, capacitors, diodes, transformers, soldering, etc.

However - we live in a time where the above, sans soldering, can essentially be done virtually:
Circuit Simulator
I would strongly suggest you become familiar with the above and go through some of the excellent examples.

If you need to use a sensor and want to research a little about the electrical/physics associated with the device, a great place to do that is GSU HyperPhysics.

But probably the greatest asset you have is Google. I always recommend that if you are setting out to build a project that you attempt to find a similar project that covers around 50% of what you intend on doing in your project. For example, if you were wanting to use an RF12B radio, solar power, and wanted to check the mailbox status then you could craft a Google query: arduino solar mailbox monitor RF12B … never under estimate what a help Google can be if you just talk nicely to her.

Good luck.

Ray
My Projects

Hi mrburnette

I don't know about my newbie status but I am getting a bit long in the tooth. I am old enough to remember my friends playing around with valves and it was as much a mystery to me then as is it to me now. My engineering background involves valves of a different kind - more years than I care to remember as a mechanical tradesman (manufacturing, construction, mining). All I needed to know about electricity was that it sparked at the end of a welding electrode, and if that stopped I would go and find a Sparkie.

My 30+ posts are only evidence that I am desperate to get a handle on this Arduino stuff (people are relying on me to do so), and I have to say that I am impressed by the way the Forum as a whole responds. This Forum goes a long way in helping me over the hump in this learning road. My thanks to everyone.

  • I did not know this from birth as some folk expect

Then you should have a serious talk with your mother about what she did wrong.

mrburnette - that http://www.hobbyprojects.com/ site is brilliant! :grin:
Grumpy_Mike - I seem to remember some talk about the milkman :sunglasses:

vagulus:
<…>
My engineering background involves valves of a different kind - more years than I care to remember as a mechanical tradesman (manufacturing, construction, mining). All I needed to know about electricity was that it sparked at the end of a welding electrode, and if that stopped I would go and find a Sparkie.
<…>

Well, we can work with you… electricity is just binary… you know, positive and negative.

The most critical information we need to know from you is what you want to do next & what did you do just before. So, if your question is about resistors - a circuit diagram or schematic is most useful (hand drawn and scanned is OK.) If your question is code related, explain what is happening, what you expected, and always attach the current code.

There are rules of engagement called “stickies” at the top of every forum, following them makes the forum process much more efficient for everyone.

One a final note, I am a little concerned by the statement, "people are counting on me… " only because 'we’in the forum do not wish you to be driven by frustration. I dare say many of us have over committed and under achieved at least once :o

Good luck on this trek,

Ray

Thanks Ray

I dare say the just-out-of-secondary-school students doing the mechanical design and construction are under more likely to be driven by frustration than I am programming this. :wink: That is not to say that the learning curve is flat, and I do appreciate the help I get here.