Datasheet

30.5.1 I/O Lines
The GCLK I/O lines (GCLK_IO[7:0]) can be used as measurement or reference clock sources. This
requires the I/O pins to be configured.
30.5.2 Power Management
The FREQM will continue to operate in idle sleep mode where the selected source clock is running. The
FREQM’s interrupts can be used to wake up the device from idle sleep mode. Refer to the Power
Manager chapter for details on the different sleep modes.
Related Links
18. PM – Power Manager
30.5.3 Clocks
The clock for the FREQM bus interface (CLK_APB_FREQM) is enabled and disabled by the Main Clock
Controller, the default state of CLK_APB_FREQM can be found in Peripheral Clock Masking.
Two generic clocks are used by the FREQM: Reference Clock (GCLK_FREQM_REF) and Measurement
Clock (GCLK_FREQM_MSR).
GCLK_FREQM_REF is required to clock the internal reference timer, which acts as the frequency
reference.
GCLK_FREQM_MSR is required to clock a ripple counter for frequency measurement. These clocks
must be configured and enabled in the generic clock controller before using the FREQM.
Related Links
15. MCLK – Main Clock
15.6.2.6 Peripheral Clock Masking
14. GCLK - Generic Clock Controller
30.5.4 DMA
Not applicable.
30.5.5 Interrupts
The interrupt request line is connected to the interrupt controller. Using FREQM interrupt requires the
interrupt controller to be configured first.
Related Links
10.2.2 Interrupt Line Mapping
30.5.6 Events
Not applicable
30.5.7 Debug Operation
When the CPU is halted in debug mode the FREQM continues its normal operation. The FREQM cannot
be halted when the CPU is halted in debug mode. If the FREQM is configured in a way that requires it to
be periodically serviced by the CPU, improper operation or data loss may result during debugging.
30.5.8 Register Access Protection
All registers with write access can be write-protected optionally by the Peripheral Access Controller
(PAC), except the following registers:
SAM D5x/E5x Family Data Sheet
FREQM – Frequency Meter
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 832