18.5.12 Main Clock Clock Frequency Measure n Reference Clock Cycles

Selects the number of reference clock cycles to be used for counting measurement clock cycles. The CLKCTRL.MCLKCFMnREFNUML and CLKCTRL.MCLKCFMnREFNUMH registers represent the 16-bit value, CLKCTRL.MCLKCFMnREFNUM. The low byte [7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01. The REFNUM register is NOT buffered by a TEMP register to ensure a consistent readout. The MSB of the REFNUM register is bit 15. This register is locked when MCLKCFMnCTRLA.MEN = ‘1’ and an attempted write when locked will generate a bus error.

Name:	MCLKCFMnREFNUM
Offset:	0x16 + n*0x10 [n=0..1]
Reset:	0x00
Property:	-


Bit	15	14	13	12	11	10	9	8
	REFNUM[15:8]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	7	6	5	4	3	2	1	0
	REFNUM[7:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0

Bits 15:8 – REFNUM[15:8] CFM Reference Clock Measurement Cycles High

These bits hold the MSB of the 16-bit REFNUM register.

Bits 7:0 – REFNUM[7:0] CFM Reference Clock Measurement Cycles Low

These bits hold the LSB of the 16-bit REFNUM register.