use nrf5340 DK ,cannot control P0.15 output,(p0.9 CS2) can high or low,but (CS P0.15)can not high ,always low,

[zhouhaifang]

[Kenneth]

Looking at the user guide I can find that P0.15 may be connected by default to external flash memory:
https://infocenter.nordicsemi.com/pdf/nRF5340_DK_User_Guide_20210304.pdf