Configuration Change Protection

This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four CPU instructions.

Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the protected register unchanged.

The following registers are under CCP:

Table 1. CPUINT - Registers Under Configuration Change Protection
Register Key
The IVSEL and CVT bit fields in CPUINT.CTRLA IOREG