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# 1.40 TrustZone Systick Periodic Timeout

This example application shows how to use the SysTick to generate periodic interrupts on both Secure and Non-secure modes.

## Description

This demonstrates TrustZone feature and uses two projects viz, Secure and Non-Secure Project that work together on the same MCU and offering security isolation between the Trusted and the Non-trusted resources in the device.

- Secure project uses secure SysTick timer to generate periodic interrupt every 50ms to toggle a GPIO pin and an LED
- Non-secure project uses non-secure SysTick timer to generate periodic interrupt every 100ms and toggles a GPIO pin

## Components Used

- Systick - Secure and non-secure systicks
- LED - Configured as non-secure mode
- SECURE_PIN and NON_SECURE_PIN - Configured as secure and non-secure mode respectively

## 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 as shown below:

Type | Path
--- | ---
Project group | apps/trustZone/systick/systick_periodic_timeout
Secure Project | apps/trustZone/systick/systick_periodic_timeout/Secure/firmware
Non-Secure Project | apps/trustZone/systick/systick_periodic_timeout/NonSecure/firmware

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

Project Name | Description
--- | ---
sam_l11_xpro_Secure.X sam_l11_xpro_NonSecure.X | Secure and Non-secure MPLABX project for SAML11 Xplained Pro Evaluation Kit

## Setting Up the Hardware

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

Project Name | Description
--- | ---
sam_l11_xpro_Secure.X sam_l11_xpro_NonSecure.X | SAML11 Xplained Pro Evaluation Kit

### Setting Up SAM L11 Xplained Pro Evaluation Kit

- Connect the Debug USB port on the board to the computer using a micro USB cable
- Connect an oscilloscope/Logic analyzer to monitor the PORT pin PA08 (Pin #14 on EXT1)
- Connect an oscilloscope/Logic analyzer to monitor the PORT pin PA09 (Pin #13 on EXT1)

## Running the Application

1. Open the project group in the MPLAB X IDE and set the non-secure project as main project
2. Build and program the application
3. Observe the output for SAML11 Xplained Pro Evaluation Kit as follows:
   - LED0 and PA08 (Secure pin) is toggled every ~50ms in secure project.
   - PA09 (Non-secure pin) is toggled every ~100ms in non-secure project