Martin Harris - Moderator Posted March 2 Share Posted March 2 On 21/02/2025 at 11:56, Phil Green said: if its for the rangers hand-held radios it wont be 2.4ghz, more likely UHF 430-460 megs ish and only active when they're speaking. If its for park-wide internet access it could be 2.4 in constant use. Or it could well be a phone mast. If you can get a photo of the actual aerial itself, the band will be apparent, and if it runs high power it will have warning signs. Do you have a scanner of any sort? A 2.4 scanner is easy to make: https://mode-zero.uk/viewtopic.php?f=42&t=1008 any Bearcat, Uniden etc UHF scanner will confirm UHF walkie-talkies. This thread was created from a sub discussion prompted by this post in another topic. The scanner was designed and programmed by Martin Round (Ceptimus) Seems like a great idea - I put one together today but I'm missing something (no in depth knowledge of Arduino to help me) and although it seems to have loaded the sketch, it doesn't seem to function as I'd expected - nothing past a "front screen". I'm using the 1.3" OLED - should I have modified any code? The notes suggested it was just a case of uploading the sketch as downloaded... Temporary test wiring Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 2 Share Posted March 2 (edited) Hi Martin, which version did you make, separate arduino and NRF24L01, or using an RF-Nano? (if so, which RF-Nano?) One thing to be aware of with the RF-Nano is that there is no agreement on the allocation of two NRF24 pins CE and CSN. T-stars use D7 & D8, Keywish (our favourite) use D10 and D9. Often the manufacturer doesnt say which! Coincidentally yesterday I separately needed to test an OLED and an RF-Nano so I put one of these together, works great. If you have no joy, PM your postal address & I'll send yesterdays RF-Nano FoC programmed & working & ready to connect to your oled. The splash screen should dissolve to the XY coord scales, then any 2.4 activity should animate it above freq scale Heres one monitoring a sweep generator: Edited March 2 by Phil Green Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2 Author Share Posted March 2 Thanks Phil - very kind offer. I’ve been doing some further testing and tried loading a different software - nRF24L01pScannerOled_RFNano and noticed that it functions OK while the Nano is powered from the programming port. I’m not sure how to identify the Nano - there don’t seem to be any markings. It seems to point to the way it’s powered but I’m sure I’ve followed the instructions (battery negative is connected to GND on the other row of pins). Please excuse the dodgy soldering - this was just quickly knocked together to confirm operation before I mount it in a printed case… Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 2 Share Posted March 2 (edited) 57 minutes ago, Martin Harris - Moderator said: ...and tried loading a different software - nRF24L01pScannerOled_RFNano and noticed that it functions OK while the Nano is powered from the programming port. Ah thats good, the only code change from Martins (Ceptimus) very original scanner is to the CE and CSN pins so it looks like your RF-Nano is yet another variation using 9 & 10 in reversed order wrt the Keywish that we generally use. Thats fine, sometimes you have to find them manually, on the T-Stars I was able to work out the CE & CSN connections under a microscope. The way the code is written its not immediately obvious how to change CE/CSN as it uses AND & OR masks as well as the pin definition, hence posting read-to-go versions. We could add yours to the mode-zero post if thats now the 'currently available' RF-Nano. So its all working ok now? PS I recognise that wire, are you ex BT Martin? 😉 (Blue, orange, green, brown, slate A-legs and B-legs white, red, black, yellow, violet & all that!) (why do I remember that but cant remember why I went upstairs?) . Edited March 2 by Phil Green Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2 Author Share Posted March 2 Not really. It won’t function using the 9V battery - seems quite time critical on how long you leave between connections and stops loading at different stages - never getting as far as scanning though. Powered from my PC via the onboard USB connection, it scans but seems to freeze after removing a nearby 2.4GHz source (my transmitter). I’d be delighted to try it with your board if there’s no fix - but please let me cover your costs. PM sent… Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2 Author Share Posted March 2 21 minutes ago, Phil Green said: PS I recognise that wire, are you ex BT Martin? 😉 (Blue, orange, green, brown, slate A-legs and B-legs white, red, black, yellow, violet & all that!) (why do I remember that but cant remember why I went upstairs?) . I wondered if you’d spot that Phil! Those colours are one of the things you never forget - as well as the order of the wires to a telephone dial, but I can’t quote the mnemonic here… Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 2 Share Posted March 2 (edited) Could be a duff RF-Nano, should run fine on 9v via Vin or 5v via usb... I've had a couple of duffers, which is why I was testing yesterday. There is one thing you could try. Strictly, I2C should have a 1k pull-up to 5v on both SDA and SCK (A4 and A5) but usually you get away without them. Try that, two 1k resistors (or thereabouts) from 5v to A4 and to A5, either on the nano or on the display (prob easier on the display) Edited March 2 by Phil Green Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2 Author Share Posted March 2 Sadly, no difference at all with the resistors added. It still seems to freeze at random points in the boot sequence but never gets to the point where the text “dissolves” before the scan starts. This is as far as it goes at best (many attempts stop earlier) and you can see that the text is just starting to dissolve after completing that “page”. The sequence always completes when powered via the USB connector. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2 Author Share Posted March 2 If it’s any help in working out where the problem is, I just powered it from a 5V source onto the battery connector and it worked fine. I’ve measured between ground and the 5V pin while powered from the 9V battery and that is giving 4.99V so with my limited understanding of Arduinos, it leaves me none the wiser! Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 2 Share Posted March 2 That sounds like the built-in 5v regulator is somehow playing up, even though its giving the right voltage. Most odd. Maybe try a tantalum across the 5v? or across the 9v input? or both? 😁 or try 100n as it could be supply noise? (unlikely on a battery) Shouldnt need any of this though, they usually just work! I just put (yet) another together as a test and it worked right away except the display (taken from a new sealed bag) had a few lines missing, swapped the display and its perfect, the quality of components from Aliexpress seems a bit hit & miss eh. I have some more 1.3" oleds on order so we'll see if they're any better! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2 Author Share Posted March 2 I tried capacitors (47nF) with no improvement but I established the range of input voltages which allowed it to start and run - 3.9 to 6V. It might be simpler to run it from 3 or 4 NiMH cells - I've got some 150mAh ones which should give several hours operation per charge (it runs at around 20mA) and fit in the space for a PP3 in the case I've printed very easily... Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 3 Share Posted March 3 Most peculiar 🙂 I'll send one anyway, its programmed & tested, just needs the PP3 and display connecting. Most of my 9v bits & bobs use a couple of those smaller vape cells, two are about PP3 sized. The only thing you have to be careful of is that unlike a zinc PP3 even the small ones can give several amps if you have a short, more than enough to blow a PCB track! 🥴 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 3 Author Share Posted March 3 That’s very kind of you Phil. Nice tip about the vape batteries - I hate to think how many of these have ended up in landfill - it’s good to know that one or two are not being charged and used just once! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 5 Author Share Posted March 5 Talking of which, many thanks to Phil for sending me the RF Nano. Fully expecting it to work, I soldered it in place and turned it on - but it was the same as my original! Have I been particularly stupid - no, careful inspection and cross reference with the “diagram” confirmed all wiring to be correct and all soldering was rechecked. High resistance switch contacts? Shorting the connections confirmed it wasn’t that. So I turned my attention to the display…and found what appears to be a missing capacitor! Could this be the explanation for the very strange behaviour? I’m feeling rather guilty that Phil went to the trouble of sending the replacement board but it didn’t occur to me that it might be the OLED until the unexpected same mode failure occurred. I’ll see if I can get a replacement from Ali Express as it’s unlikely that anyone would be able to identify C2’s value. Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 5 Share Posted March 5 (edited) Baffled as to how that could give the fault you described Martin - working only over a specific input voltage range? Normally of course the display and the 328P would only ever see 5v regardless of the input voltage 😀 Anywho, pending a parcel from Aliexpress, I have just one display left, its tested & working fine, I'll send it tomorrow Martin. I almost put it in there wth the RFnano anyway... . Edited March 5 by Phil Green Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 5 Author Share Posted March 5 Thanks Phil - but I’ve got one coming from EBay. It will certainly be interesting to see how replacing the OLED affects operation…I couldn’t see any logic as the 5V seemed to be regulated correctly although the only way I could get it to work was with the quite limited range of input voltage. I’ll feed back the result in case anyone else encounters problems as I’d be surprised if I’m the only forum member putting one of these together. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 6 Author Share Posted March 6 Off topic posts specific to scanner construction from the "swamping" thread moved here to unclutter the topic. As a moderator, I feel a little guilty for starting the sub-discussion so I'll offer a little present for anyone contemplating building one of these simple devices (thanks for the info and help from Phil Green) so if it's of any use to anyone, I've attached an STL file for printing the case I designed for mine. Spectrum Analyser Case.stl I tapped the holes for the display mounting screws but this version has the threads printed which should allow short M3 screws to run in. The case bottom should attach with servo screws and the Arduino slips in at an angle - I retained mine with a couple of dabs of UHU POR on the top edge which allows easy removal. 1 Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 6 Share Posted March 6 (edited) Could you edit the first post of this new thread to credit Martin Round ("Ceptimus") for the original design please Martin (two Martins here!) Its quite an old project, Martins original used a separate NRF module with a nano or promini, the 'easy' option uses an RF-Nano, either works identically. The display used is a 1.3" OLED available cheaply from ebay/Ali/Banggood which must be an I2C (aka IIC), these have 4 connection pins but be aware that some manufacturers arrange the four pins in a different order. Some are SPI with 7 pins - these are not the ones. Some are both which is too awkward to explain here, just buy the I2C display 🙂 Original: https://mode-zero.uk/viewtopic.php?f=9&t=17&p=18#p18 RF-Nano: https://mode-zero.uk/viewtopic.php?f=42&t=1008 If you're mounting this tiny display with four (relatively) hulking screws be aware that its a fragile glass plate over the LED substrate, if you tighten down four screws that aren't absolutely perfectly level, the display will very likely twist and separate. I generally mount mine with a dab of POR in each corner instead of screws. Edited March 6 by Phil Green Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 6 Author Share Posted March 6 Thanks for the advice Phil. Luckily - and more in deference to the fine thread in the PLA case - I used minimal force on the screws! I’ve added an appropriate note as requested. 1 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 11 Author Share Posted March 11 On 05/03/2025 at 23:40, Martin Harris - Moderator said: Thanks Phil - but I’ve got one coming from EBay. It will certainly be interesting to see how replacing the OLED affects operation…I couldn’t see any logic as the 5V seemed to be regulated correctly although the only way I could get it to work was with the quite limited range of input voltage. I’ll feed back the result in case anyone else encounters problems as I’d be surprised if I’m the only forum member putting one of these together. Well, I don't think it will come as a total surprise to Phil that connecting a new OLED made no difference! My replacement OLED didn't have anything connected to the C2 terminals either... The scanner works perfectly when connected to a 5v supply to the onboard USB port but despite measuring 5.08v at the 5v terminal when supplied by the PP3 it resolutely refuses to complete the boot sequence. Phil - can you recall whether you powered the board that you so kindly sent me from a PP3 while you were testing it? Scanner powered via on-board USB I'm wondering if anyone else has tried running this simple circuit while powered from other than the USB port? Perhaps something has been changed in the currently available Arduino boards? Anyone else here having a go at putting one together ? I see 8 people have downloaded my case design... Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 11 Author Share Posted March 11 As soon as I hit enter on the post above, I had a thought based on some research I did a few days ago and Googled "Arduino pull up resistors" - which came back with a suggested value of 10k. With little to stop me and in the fine old spirit of "poke and hope", I did a temporary lash up based on Phil's earlier suggestion and lo and behold, it worked straight away! I'm not entirely sure about the function of these pull ups, which seem to be to better define 1 or 0 conditions and how this affects the working of the circuit but perhaps 1k resistors are now too low a value with the latest boards? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 11 Author Share Posted March 11 Hmmm....the saga continues now that I've put everything back together. While it now starts up and functions (almost) every time, the display locks up after a varying amount of time. It looks like I might have to continue experimenting with resistor values... One slight worry though - when my wife just turned on the (fairly new) microwave, it detected strong activity! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 11 Author Share Posted March 11 Got nowhere with the trial and error approach other than establishing that going much above or below 10k made it worse. A4 (SDA) seems to be the more critical pin to pull up in order to get it to complete the boot up. I'm wondering if a small 5v regulator to power it through the Arduino's USB connector would be the easiest solution. Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 11 Share Posted March 11 (edited) Hi Martin, this is most strange, loads of these have been built, I've done maybe 20 myself... Trying to recreate your problem I've lashed-up four over the last few days without problems, powered either from USB or via a 9.6v transmitter battery I had handy. My cased ones have used mix of Duracell & Zinc PP3s, 2s Lipos, 2s vape-cells... None of mine (and none I'm aware of that others have made) have needed the I2C pull-ups, they shouldnt be necessary as the display has its own. The suggestion was just me clutching at straws. So yours is playing up using the RF-Nano I sent and a brand new display? Presumably you've tried different batteries? Heres one of mine, they're all very similar: Edited March 11 by Phil Green Quote Link to comment Share on other sites More sharing options...
Phil Green Posted March 11 Share Posted March 11 (edited) Here's one that lives in a Tic-Tac box, and another lash-up, both use the same RF-Nano as I sent... 🙂 Edited March 11 by Phil Green Quote Link to comment Share on other sites More sharing options...
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