Hi,
I had some erratic results when I hook these devices via SPI, using a level shifter (e.g. TXB0104) to protect the nRF52. When I look at the schematic for the nRF52-DK I see that there is no level shifting on the pins intended for Arduino shields. Do I read this correctly? If so I can presumably connect the devices directly which would eliminate any problems cause by the level shifters.