Configuration Change Protection (CCP)

This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a given 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 it unchanged.

The following registers are under CCP:

Table 1. CLKCTRL - Registers Under Configuration Change Protection
Register Key
CLKCTRL.MCLKCTRLA IOREG
CLKCTRL.MCLKCTRLB IOREG
CLKCTRL.MCLKCTRLC IOREG
CLKCTRL.MCLKINTCTRL IOREG
CLKCTRL.OSCHFCTRLA IOREG
CLKCTRL.PLLCTRLA IOREG
CLKCTRL.OSC32KCTRLA IOREG
CLKCTRL.XOSC32KCTRLA IOREG
CLKCTRL.XOSCHFCTRLA IOREG