BLE doesn't work in the custom board of NRF52840

[salvatore_]

Hi, 

I recently started using Nordic microcontrollers and I have designed a custom board based on nRF52840 and its works except for Bluetooth.

First of all, I'm using vscode+zephyr to program the board, and the firmware I'm using is a sample firmware "peripheral_uart".

1. First I tried to upload the firmware on nrf52840DK and it works properly! - I see the device via the nRF connect smartphone app 
2. Next, I upload  the firmware onto the custom board and...
   1. The firmware is uploaded correctly.
   2. UART connection(TX[P0.14]-RX[P0.09]) OK!
   3. All other gpios are working
   4. Log print "Bluetooth initialized" - but if I try to search for the device with the nRF connect smartphone app, I can't find it

I have done several tests, both hardware(HF crystal is correctly mounted), and software. I've tried resoldering the board but nothing still doesn't work. I have been using these microcontrollers for a short time, so my little experience does not help me solve the problem.

Schematic:

[Bendik Heiskel]

Since the firmware works correctly on the nRF52840 DK the problem would be with the custom hardware. As I mentioned, if the antenna is not tuned correctly the very little power will be transmitted. If C3, L1 and C7 are the only components between the ANT pin and the antenna, I expect the antenna impedance will not be tune to 50 ohm as is required for good antenna performance.

[salvatore_]

I am not very convinced that the problem is the antenna, okay the signal might be very weak but not nonexistent. I also tried to run a test via RSSI Viewer but nothing, it is as if the antenna is not totally connected.

Could there be some error in the circuit? I followed configuration no. 6.

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fref_circuitry.html

I cannot find the problem, perhaps I should redesign the board using an antenna PCB as in the dk. However, before redesigning the board I would like to be sure that the problem is that.

[Bendik Heiskel]

Sorry for not getting back to you sooner.

The nRF part of the schematic looks good.

You should contact Ignion, the antenna manufacturer, and get them to have a look at your PCB. They should be able to confirm whether your lack of antenna matching components is the cause of the problem.