SAM4L Datasheet, PDF (517/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/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.
22.3 Block Diagram
Figure 22-1. Frequency Meter Block Diagram
CLKSEL
START
CLK_MSR _Counter
VALUE
CLK_REF
Timer
Trigger
ISR
REFSEL
REFNUM,
START
22.4 Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described
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.
42023C–SAM–02/2013
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