NRF52832 antena set-up

[Joseph]

Hello,

I'm currently creating my own custom board for NRF 52832.

I put everything together, but I can't detect my custom board through Bluetooth using the NRF connect app. 

I'm using QFAA and QFAB QFN48 with DC/DC regulator setup.

Here I've attached the schematic of my custom board and all the components.

I'm new to designing an antenna for BLE. I believe there's something wrong with the antenna design. 

Please let me know if there's anything wrong with this design. 

Thank you!

Custom_nrf52832chip.pdf

 

[JONATHAN LL]

Hi, 

Can you share the layout files? GERBER format or PDF maybe?

If you are able to program and read\write to the device then something is working at least. 




We also have guides: https://devzone.nordicsemi.com/guides/hardware-design-test-and-measuring/b/nrf5x/posts/general-pcb-design-guidelines-for-nrf52-series 
And a video made with one of our engineers: 

PCB Antenna - How To Design, Measure And Tune 


Also we will help with schematic and  layout review, all you need to to is submit a review request and share the schematic and layout files. 



Feedback on the schematic you shared. 

The antenna is missing its antenna matching network, so the antenna might not be tuned properly. 



In the layout it should follow the ref design, and specifically the radio section should follow the ref layout as deviation form this layout can cause issues with suppression of harmonics. Tuning might be needed to achieve the best performance. 


Also it is recommended to short two of the GPIO pins to ground, pin 37 and 38. 




Regards,
Jonathan

[Joseph]

Hi Jonathan!

Thank you so much for the reply.

I'm not sure what you mean by layout file. I'm creating my CAD file using Rhino 7 software.

I have attached a pdf file for the schematic:NRF52832_cad_final_Design.pdf

Also, I used the AppCad program to calculate the dimension that is required for the antenna.

This is the result that I got: 

My PCB will be made out of 9-micron copper laminated on 25 microns Polyimide laminate.

Also, what is the reasoning for connecting GPIO pins(37 and 38) to the ground pin??

Please let me know what you think!

[connorshannon]

Hello Jonathan,

To be perfectly honest, I don't fully understand your suggestions here. For one, I don't believe I can even connect my custom circuit to my laptop to use the RSSI viewer, since based on my understanding and your images it appears that a wired USB connection is required. When you suggest the radio test sample, is that meant to test whether it is a software or hardware issue? The code has not been updated, and works perfectly fine with the dk and with the older (completely identical to current design) model of our custom circuit. 

The update since my last message is that we went ahead and purchased the antenna and manufactured the circuit using it. Now, the PPK shows a current draw of ~90mA, but still doesn't seem to be advertising over bluetooth. 

Do you have any initial thoughts regarding the questions that I asked in the previous post, or do you need me to try and perform your recommended tests before you would be able to have a guess?

Lastly, I'll attach the schematic of our current design. Thank you for the help.

Regards,

Connor S

NASA research notes_250325_160255.pdf

[JONATHAN LL]

connorshannon said:

To be perfectly honest, I don't fully understand your suggestions here.

Sorry for the poor description, let me try and clarify.

In the image i shared here I use two DK's as example hardware, but only one is the used as the sensor\measuring unit. 

So what I wanted you to do was to flash the example hex file i provided or use the radio test sample to your custom hardware. 

Then use a DK with the RSSI viewer app to see if you see the custom HW show up as a spike. on the RSSI Viewer app. 

I wanted to do this to see if there is a an issue with the radiated results. If there is no signal that shows up then its safe to guess that there si something wrong with the RF path or the antenna. 

If you do get a strong signal then the issue might be sw related or it could be the 32MHz crystal, at least in many cases that is the case. 

So this is what you can try, it might show a strong radiated peak, if that is the case you might be able to get some wireless communication but whitout propper equipment this will be extremely difficult to achieve. 

But I have viewed the schematic before, and my previous comments still stand on that this design is unlikely to be able to have any successful radio communication.
The design simply does not allow it.  

2 layers is needed and the top and bottom copper ground planes needs to be connected. 
Dedicated radio matching and dedicated antenna matching network is needed. 

single copper plane will not do as there will be lots of issues with the return current path and grund loops for the system. 

I also want to add that you need to supply all the VDD pins with VDD, they need to be connected for the device to operate correctly. Not supplying VDD to all the VDD pins will put the device in a unstable state and things might work, or might not.  

Regards,
Jonathan

[JONATHAN LL]

You need to add VDD on these sections. 

Can be good to also have the red marked areas connected to ground. 

But I recommend that you switch to KiCad or som other SW here to do the design, this will greatly help with the design process. There are also some relatively inexpensive PCB manufacturers like PCBway and JLCPCB that we have seen some customers use to make some designs.

Regards,
Jonathan

[connorshannon]

Thanks for the detailed posts, these were very helpful. We're going to look into a few of the things that you mentioned and get some more information. If things still aren't working after we try some other stuff, do you think there's any possibility we could quickly meet over zoom to discuss this? I'm not sure if that's something that is ever done for devzone posts, so if not no worries. Either way, we'll give what you mentioned a try and reach out once we've done so.

Regards,

Connor

[JONATHAN LL]

Hi Connor, 

connorshannon said:

do you think there's any possibility we could quickly meet over zoom to discuss this?

We dont do this. Only way to get this is through our sales department but that is not something that happens often.

But I will happily answer any questions here and to my best to help you reach your goal here. 

So feel free to keep asking here and I will do my best to help out. 


I went digging though some of the other tickets here related and found an image in another ticket, looks like you are manufacturing your own pcb's here. Either machined out or with etching, this does work well and is relatively fast but can be difficult for more complex designes that involve radios. 

I also did this some time ago and even with a design that was close to the reference design it did not yield great results as many of the PCB's did not preform well. I also hade to hand stich the top and bottom layer together with thin wire or lots of solder to make sure there was a consistent grund plane here, process is a lot more involved and there was room for more human error in my experience. 

Regards,
Jonathan