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# 1.4 Clock Configuration

This example application shows how to configure the clock system to run the device at maximum frequency. It outputs a prescaled clock signal on a GPIO pin for measurement and verification.

## Description

Clock system generates and distributes the clock for the processor and peripherals. This example application shows how to use the clock manager to configure the device to run at the max possible speed. A prescaled clock signal is routed to GPIO pin to measure the frequency and accuracy of the internal device 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 be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/clock/clock_config/firmware.

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

Project Name | Description
--- | ---
sam_9x75_curiosity.X | MPLABX project for SAM9X75 Curiosity Development Board
sam_9x75_curiosity_pro.X | MPLABX project for SAM9X75 Curiosity Pro Development Board

## Setting Up AT91Bootstrap Loader

To load the application binary onto the target device, the user needs to use at91bootstrap loader. Refer to the at91bootstrap loader documentation for details on how to configure, build and run bootstrap loader project and use it to bootstrap the application binaries.

## Setting Up the Hardware

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

Project Name | Description
--- | ---
sam_9x75_curiosity.X | SAM9X75 Curiosity Development Board
sam_9x75_curiosity_pro.X | SAM9X75 Curiosity Pro Development Board

### Setting Up SAM9X75 Curiosity Development Board

- Connect the UART DEBUG J35 on board to the computer using a UART-FTDI cable (to enable debug com port)
- Connect the USB port J2 on board to the computer using a micro USB cable (to power the board)

### Setting Up SAM9X75 Curiosity Pro Development Board

- Connect the UART DEBUG J63 on board to the computer using a UART-FTDI cable (to enable debug com port)
- Connect the port J1 on board to the computer using a Type-C USB cable (to power the board)

## Running the Application

1. Build the application using its IDE.
2. Observe the clock of 1 kHz on clock output pin.
3. LED should be blinking continuously.

Refer to the following table for clock output pin and LED name for different boards:

Board | Clock Output Pin | LED Name
--- | --- | ---
SAM9X75 Curiosity Development Board | PB18 (INT Pin on the mikroBUS Connector) | RGB_LED (Blue)
SAM9X75 Curiosity Pro Development Board | PB18 (INT Pin on the mikroBUS Connector) | RGB_LED (Blue)

Rev: E