Custom board not seen by IOS device but it is seen by NRF-Connect Desktop

[rogerarchibald]

Hi There,

I've been developing a product using the NRF52DK.  I had some custom PCB's made after I had my circuit designed, and I programmed them with the NRF52DK.  Now my boards and the NRF52832 on the DK are running the exact same firmware.

With the NRF52DK, I can connect to my service on NRF Connect for IOS and Desktop (with an NRF51 dongle). 

With my boards, I can't see them with IOS (using NRF Connect or LightBlue) but I can see them using NRF Connect Desktop.  

When I scan with NRF Connect Desktop, my boards' RSSI indicates a fairly strong signal (~ -55dBm) and I can connect and view/control all the characteristics fine.  

I'm going to continue poking around to try to understand what's different but I'm quite stumped as to why IOS will only see the NRF52832 on the DK, but NRF Connect Desktop will see either the DK or the custom board.  I've tried an iPhone and an iPad and got the same result.

Any suggestions would be greatly appreciated!

Thanks,

Roger

[AmbystomaLabs]

I made a mistake.  You will still need your turn off fet for the solenoid due to the boost topology.

Sorry, I missed that. 

Though, I would still use a packaged device instead of the way you have it in the schematic.

[rogerarchibald]

The solenoid current is pretty substantial (~2A @12V) and the prepackaged boost drivers aren't an option here.  The 5A rating is for the internal FET, and if I'm looking at say 3.5V Vbatt boosting up to 12V @ 2A, the internal FET is going to get fried.  Those solutions are great for a regulated supply at a moderate load, but my discreet boost is sacrificing simplicity, size and regulation for pure beefiness.  I'm planning to run this off of a 26650 battery which will supply more than enough current, provided I have a decent efficiency (and make sure that the power LED is turned off as part of the solenoid fire function!).  One thing that my current rev doesn't have, but is needed, is a 'solenoid sense' circuit so I don't fire up an unregulated boost designed to provide that kind of power when there's no load.  I have a simple circuit in mind that I think will work nicely. 

I've used little battery managers (Microchip 73831) with smaller lipos.   I'm not sure if I'll go that route here...I haven't looked into compatibility with the big batteries and had just assumed on using an external charger, but an on-board charger with a micro USB connector might be a good option here.  That is what I used for the battery on the remote of the first revision of OpenTrap.

Again, I'm sure you're a busy man and I appreciate you taking the time to provide feedback on my design.  If by any slim chance you're planning to be at the SF Maker Faire this weekend, I would like to offer to buy you a frosty beverage!

Cheers,

Roger

[AmbystomaLabs]

Sorry, my company HQ is out of Florida and currently I'm working out of Massachusetts.  I get out to SF once in a while, sometimes for Arm Tech Con or ESC Silicon Valley.

If I can work it into my schedule, I will spin a design for your live trap.  The ultrasonic stuff looks interesting and I'm thinking about doing a PCB artwork based output match for the RF and antenna that Nordic might like.

I'll pass along the design info if it happens.

[rogerarchibald]

Thanks for even mentioning that, but in the end I will end up respinning this myself....it's the best way to learn!  That said, if you had any more robust antenna layouts from previous builds that you may be willing to share, I would definitely appreciate that.

Ultrasonic is really interesting.  The first spin of the 8-bit trap used a PIR sensor, but it was too prone to false positives when set outside on a sunny day.  You're correct that the ultrasonic is driven at 40KHz, but I've never seen any critters hesitate to go in there any more than they do with a standard live trap.  Obviously 40k is too high for human hearing, but I fire the ultrasonic every 100mS and there's a faintly audible 10Hz 'ticking' when the transmitter is firing.

[rogerarchibald]

Attached is the next spin on this.  In the zip are gerbers, Eagle files and a schematic pdf.  Taking a bit of your advice, I've gone to a 2-layer board and implemented bucks for VCC and onboard for the NRF.  After messing around with the first board powered off of a single 3.7V battery, I think that I'm running too close to the limits of what that can do when running the boost converter, especially once it gets down <3.7V.  Things work great at 4.2V, but I want a bit more headroom for comfort, so I'll run this off of 2x smaller 3.7V liPos in series.

I have to clean up some reference designators on the board, and I've not yet gone over the schematic with a fine-tooth comb for errors, but any thoughts/pointers on this would be well received.  I'm looking around for access to some RF gear, hopefully I can get some eyes on what's happening with the radio...

Thanks!

RogerRev2Files.zip