On my QN9090 development board I've placed the following crystal:
MCSJK-7I-32.00-10-30-60-B-30 32 MHz, SMD, 5mm x 3.2mm, 30 ppm, 10 pF (Farnell 2854099).
The MCU was working fine, all the peripherals except the radio. After a day of debugging I've placed a scope on the XTAL output and there was a low frequency wobbling on top of the 32MHz while the signal on the QN9090-DK006 was nice and clean. This prompted me to replace the crystal. I've used a
Q24FA20H00196 32 MHz, SMD, 32MHZ 8PF 2.5mm x 2mm, 10 ppm, 8pF (Farnell 2723231)
which has a smaller footprint and I've soldered it dead bug style on the 5x3.2mm footprint.
This instantly solved the problem and the radio started working.
According to the datasheet you can use any 32MHz crystal up to +/-40ppm and on the DK006 kit a crystal with 6pF loading caps is used. My explanation for the above behavior is that the larger crystal needed more energy to oscillate and the driver inside the QN9090 part was struggling.
This is just a heads up for others to carefully select your crystal.
