18.3.14 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:
Register | Key |
---|---|
CLKCTRL.MCLKCTRLA | IOREG |
CLKCTRL.MCLKCTRLB | IOREG |
CLKCTRL.MCLKCTRLC | IOREG |
CLKCTRL.MCLKINTCTRL | IOREG |
CLKCTRL.MCLKINTFLAGS | IOREG |
CLKCTRL.MCLKTIMEBASE | IOREG |
CLKCTRL.MCLKCFD0CTRLA | IOREG |
CLKCTRL.MCLKCFD1CTRLA | IOREG |
CLKCTRL.MCLKCFM0CTRLA | IOREG |
CLKCTRL.MCLKCFM0CTRLB | IOREG |
CLKCTRL.MCLKCFM1CTRLA | IOREG |
CLKCTRL.MCLKCFM1CTRLB | IOREG |
CLKCTRL.OSCHFCTRLA | IOREG |
CLKCTRL.PLLCTRLA | IOREG |
CLKCTRL.OSC32KCTRLA | IOREG |
CLKCTRL.XOSC32KCTRLA | IOREG |
CLKCTRL.XOSCHFCTRLA | IOREG |