BLE difference between nrf51822 CDAB and QFAC

[unzeitig]

When I tried S110 examples like BLE proximity, beacon and hrs on QFAC, it works without any problem. Unfortunatelly I can not see any activity on pin VDD_PA of CDAB. Is there any difference between both chips from BLE point of view? How to simply debug it?

[Jørn]

Yes, the CPU is typically running from the internal RC oscillator. The crystal oscillator will remain off when the radio is not active. The crystal oscillator signal is used as a reference signal for the 2.4GHz generation. Oscillations will only be present on the crystal terminals when the radio is active, however due to its sensitivity to capacitances you typically cannot measure it with an ordinary oscilloscope probe, as the additional capacitance from the probe would interfere. You could make a test with the timer modules, by choosing the crystal oscillator as the clock source for the HFCLK and using the timers to toggle a pin f.ex. It would be best to do this bare metal to remove any other error source. You can find some bare-metal examples here. You can take the timer example and add some code to initialize the HF XTAL.