External and miscellaneous requirements

For correct operation of the SoftDevice, it is a requirement that the crystal oscillator (HFXO) startup time is less than 1.5 ms.

The external clock crystal and other related components must be chosen accordingly. Data for the crystal oscillator input can be found in the relevant System on Chip (SoC) product specification (Additional documentation).

When the SoftDevice is enabled, the SEVONPEND flag in the SCR register of the CPU shall only be changed from main or low interrupt level (priority not higher than 4). Otherwise, the behavior of the SoftDevice is undefined and the SoftDevice might malfunction.