Atmel SAM4L Xplained Pro Starter Kit Atmel ATSAM4L-XSTK ATSAM4L-XSTK Data Sheet
Product codes
ATSAM4L-XSTK
523
42023E–SAM–07/2013
ATSAM4L8/L4/L2
22. Frequency Meter (FREQM)
Rev: 3.1.1.1
22.1
Features
•
Accurately measures a clock frequency
•
Selectable reference clock
•
A selectable clock can be measured
•
Ratio can be measured with 24-bit accuracy
22.2
Overview
The Frequency Meter (FREQM) can be used to accurately measure the frequency of a clock by
comparing it to a known reference clock.
comparing it to a known reference clock.
22.3
Block Diagram
Figure 22-1. Frequency Meter Block Diagram
22.4
Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described
below.
below.
22.4.1
Power Management
The device can enter a sleep mode while a measurement is ongoing. However, make sure that
neither CLK_MSR nor CLK_REF is stopped in the actual sleep mode.
neither CLK_MSR nor CLK_REF is stopped in the actual sleep mode.
Counter
CLK_REF
CLK_MSR
REFSEL
REFNUM,
START
CLKSEL
START
VALUE
Timer
Trigger
ISR