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# 1.20 FREQM Measurement

This example application demonstrates how to use the FREQM peripheral to measure the frequency of the internal RC Oscillator.

## Description

The Frequency Meter (FREQM) can be used to accurately measure the frequency of a clock by comparing it to a known reference clock. The FREQM counts the number of periods of the measured clock with respect to the reference clock. This example application shows how to measure the CPU frequency using the 32-kHz Crystal oscillator as the reference clock.

## Downloading and Building the Application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repository or download as zip file. This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/freqm/freqm_measure_clock_freq/firmware.

To build the application, refer to the following table and open the project using its IDE.

Project Name | Description
--- | ---
sam_c21n_xpro.X | MPLABX project for SAMC21N Xplained Pro Evaluation Kit

## Setting Up the Hardware

The following table shows the target hardware for the application projects.

Project Name | Description
--- | ---
sam_c21n_xpro.X | SAMC21N Xplained Pro Evaluation Kit

### Setting Up SAMC21N Xplained Pro Evaluation Kit

- Connect the Debug USB port on the board to the computer using a micro USB cable

## Running the Application

1. Open the Terminal application (Ex.:Tera term) on the computer
2. Connect to the EDBG Virtual COM port and configure the serial settings as follows:
   - Baud : 115200
   - Data : 8 Bits
   - Parity : None
   - Stop : 1 Bit
   - Flow Control : None
3. Build and Program the application using its IDE
4. Observe output message in console as follows:

   Note that the measured clock frequency is approximate. The actual frequency may vary because of measurement error.