Why is my radio circuit working with other arduinos but not the Pro Minis?

Projects General Guidance
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Hi, I have some Arduino Pro Minis. I have both the 3.3V/8MHz and 5V/16MHz versions. I'm trying to get them to work with the nRF24L01 RF modules.

I've lightly modified some example code from the RF24 library, and gotten it working with an Arduino Micro and Nano. Basically, I just send an increasing integer from one to the other, and the receiving one displays on an LCD the latest number it received, which lets me know if a transmitter is working. Here's a pic of the receiving thing with the LCD (sorry, the LCD is washed out, shitty phone pic. It's just displaying an integer anyway). Here's a pic of the Nano transmitter, which works great.

So that all works. Now I'm trying to use a Pro Mini (tried both 3.3V and 5V versions) to transmit instead of the Nano I was using before. Here's a pic of the setup with the Pro Mini. The regulator is a 3.3V LDO. The battery is supplying that LDO and the RAW pin of the Pro Mini with ~8.5V, which should be good. Measuring the voltage out of the LDO gives 3.3V.

I looked at the pinout of the Pro Mini, and I believe I've hooked up the module to the correct MOSI/MISO/SCK pins, as well as pins 7 and 8 for the module's CE and CSN pins.

Buuut... it's not working. Nothing is appearing on the LCD. I know the nRF and its header thing work fine, because I can pop the exact one into the circuit with the Nano that works.

Even more strangely, I'm pretty sure the Pro Minis are getting programmed successfully. I can upload the Blink example to them, and that works. I'm using an Adafruit FTDI friend to upload, and that appears to be working (compiles, uploads, etc without error).

Here's the code I'm using for the transmitter, it's pretty simple. Does anyone have any suggestions? Thanks in advance. Let me know if there's anything I forgot to include.

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Probably insufficient current from the ProMini to the rf module
Notice the ProMini pinout pic you linked even states "Max 150mA when RAW powered"

3

INTP:
Probably insufficient current from the ProMini to the rf module
Notice the ProMini pinout pic you linked even states "Max 150mA when RAW powered"

Hi, thank you.

Just to be clear, I'm not powering the nRF from the Pro Mini, it's being powered externally from a hefty 3.3V regulator. Do you mean that the MOSI/MISO/SCK pins aren't providing enough current to the corresponding nRF pins? I wouldn't have expected them to need much current...

4

Do you mean that the MOSI/MISO/SCK pins aren't providing enough current to the corresponding nRF pins?

No, he doesn't .

5

All I saw was a 9V battery.
And while it might not be your problem, voltage readings have nothing to do with what current is available.

6

INTP:
All I saw was a 9V battery.
And while it might not be your problem, voltage readings have nothing to do with what current is available.

Thank you. I think the battery/regulator are capable of providing enough current, as I've used the exact same pair of them with the same circuit, but with a Nano instead, which works flawlessly.

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Images from Original Post so we don't have to download them. See this Image Guide

1280×905 230 KB

...R

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If you are using the exact same code on the Nano and on the Pro Mini I assume the only other issue is the power supply.

Could it be as simple as the fact that the Pro Mini and the Nano are not in the same place on the breadboard? In one image the nRF24 and the Arduino seem to be either side of the middle of the breadboard.

I presume the Nano and the ProMini are both working at 16MHz? If one of them is at 8MHz and you are selecting a 16MHz version in the IDE that could cause a problem.

...R
Simple nRF24L01+ Tutorial

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Robin2:
If you are using the exact same code on the Nano and on the Pro Mini I assume the only other issue is the power supply.

Could it be as simple as the fact that the Pro Mini and the Nano are not in the same place on the breadboard? In one image the nRF24 and the Arduino seem to be either side of the middle of the breadboard.

I presume the Nano and the ProMini are both working at 16MHz? If one of them is at 8MHz and you are selecting a 16MHz version in the IDE that could cause a problem.

...R
Simple nRF24L01+ Tutorial

Hi, thank you for putting the images there, I didn't know how.

It's the exact same code, and I'm using the same power supply for both (same regulator, same battery).

Ah, the Pro Mini (PM) and Nano are on different breadboards. I'm nearly positive that the problem is NOT the nRF because I can get all of them (I have 7 different ones) to work with the Nano just by popping it into the Nano circuit. I've also gotten a Micro to transmit easily, in the same way.

I also don't think the problem is one specific PM being junk, because I bought a pack of them, and have tried the 5 ones I have, same result.

I'm not sure about the Nano off the top of my head, I didn't know there were different freq versions of it (though it's working either way). However, with the PM's, I have both the 5V/16MHz and 3.3V/8MHz versions (5 of each), and I've always selected the right one under Tools->Processor in the Arduino IDE. Additionally, I've successfully programmed all the PM's I've tried (of both versions) with Blink, and they appear to work.

I guess it's possible that the PM's I bought, of both types, are junk in a very specific way (where they successfully work with Blink but their MOSI/MISO pins are messed up), but that seems unlikely. I'm guessing I'm missing something obvious... Do you have any other ideas I could try? thanks.

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Code should be identical between the boards as pins are the same, but are you correctly picking the ProMini board and proper options and proper COM port when you upload?

There's really not much to troubleshoot other than the wiring that you're certain is correct.

11

INTP:
Code should be identical between the boards as pins are the same, but are you correctly picking the ProMini board and proper options and proper COM port when you upload?

There's really not much to troubleshoot other than the wiring that you're certain is correct.

Sorry, should've mentioned that originally. I'm definitely choosing the right COM port and I choose the right board, and I choose the right version (5V/16MHz or 3.3V/8MHz, depending on which I'm using).

As a check, I often upload Blink right before I upload my actual program. thank you.

12

ranchmebro:
It's the exact same code, and I'm using the same power supply for both (same regulator, same battery).

You did not respond to my comment about your use of the breadboard.

I have not used either a Nano or a Pro Mini but I have had no trouble using an nRF24 with a breadboard Atmega 328 running at 8MHz.

Maybe get a second source for the pinout on the Pro Mini just to to be sure to be sure.

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13

may be worth checking if you need pull up / down resistors on the data line, this could be one of the differences between the two boards/cpu's

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Robin2:
You did not respond to my comment about your use of the breadboard.

I have not used either a Nano or a Pro Mini but I have had no trouble using an nRF24 with a breadboard Atmega 328 running at 8MHz.

Maybe get a second source for the pinout on the Pro Mini just to to be sure to be sure.

...R

Sorry, I missed that part. I'm not exactly sure what you mean/the significance of it, they're two different breadboards, why would the vertical position affect anything?

Hmm, I'll do that. They're definitely clone arduinos, so it's possible they have some weird pinout. Thank you.

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sureview:
may be worth checking if you need pull up / down resistors on the data line, this could be one of the differences between the two boards/cpu's

Interesting, you mean on MOSI/MISO, or the pins 7/8? I've never heard of that, but I'll look into it, thank you.

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from my point of view u have to go to arduino ide and go to tools and select proper board..
hope u understand and help it out..

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ranchmebro:
they're two different breadboards, why would the vertical position affect anything?

On some breadboards the power rails are disconnected at the the centre. Maybe the nRF24 is not getting any power.

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18

Robin2:
On some breadboards the power rails are disconnected at the the centre. Maybe the nRF24 is not getting any power.

...R

Ah, I see what you mean, thank you. I've checked at the VCC/GND pins of the nRF module itself and they have 3.3V.

Okay, I actually took my crappy little oscilloscope I built from a kit, and tried a couple things. I first looked at the SCK/MOSI/MISO pins of a couple of my working versions of this circuit (one with a Nano, one with a Micro), and then at the same pins for the circuits with the Pro Mini. Something is definitely different, whereas the SCK is a regularly spaced, fairly clean square wave on the working ones, the Pro Mini SCK is pretty messy...hmmmm...

19

tenzin:
from my point of view u have to go to arduino ide and go to tools and select proper board..
hope u understand and help it out..

Hi, thank you, I've already done that though.

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ranchmebro:
whereas the SCK is a regularly spaced, fairly clean square wave on the working ones, the Pro Mini SCK is pretty messy...hmmmm...

Maybe it would be worthwhile trying a lower clock speed?

Sorry, but apart from the Atmega328 my only experience is with an Attiny84 and an Attiny1634 - both of which do SPI without any problem.

...R