nRF52805 BLE issues

[ericberlo]

We are developing a device with the nRF52805 for BLE communication. The firmware was developed for nRF52832 and converted to nRF52805 following Nordic's documentation. The device does not have the external 32.768kHz clock and only has the 32MHz clock on the board. The crystal indicated in the data sheet was out of stock, so we selected a 32MHz crystal with 7 ppm tolerance, 10 ppm stability, 8pF load capacitance as a replacement. The firmware uploads successfully to the device via the nRF52 SDK, however, the service does not show up on the nRF connect phone application. We also have an on board antenna that was designed to have 50 ohm impedance at 2.5GHz.

We changed a few things in sdk_config.h such as setting LF_SRC to 0 for RC clock source, and made sure the correct ppm was selected. After debugging, we are getting a fatal error at nrf_sdh_enable_request()  within the ble_stack_init function. 

Please advise as to any tips on what we should change/check to get this working. 

Thank you.

[Sigurd]

Hi,

What example from the nRF5SDK are you using for testing?

Could you add DEBUG as a preprocessor symbol ?

Could you add a breakpoint to the line after nrf_sdh_enable_request(), and see what error-code nrf_sdh_enable_request returned?

[ericberlo]

Thank you for the reply. We realized a mistake in the reference circuitry for the nRF52805. We do not have capacitors C6 and C8 tied together at the DEC2 and DEC4 pins. Not sure if this is creating the ble problem but we are going to attempt to fix this issue. 

Thank you