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Arm® TrustZone® Getting Started Application on SAM L11: Step 3

Last modified by Microchip on 2023/11/09 09:09

Configure Switch Button Pin with the Secure External Interrupt Controller (EIC) to Generate an Interrupt

In this step, the switch button will be configured as per the USER_BUTTON shown in the SAM L11 Xplained Pro Evaluation Kit schematic. See the following image.

User button schematic

In MPLAB® Code Configurator (MCC), select the Pin Settings tab and then scroll down to 25 in the Pin Number column and configure the PORT pin PA27 as an external interrupt pin for switch functionality.

Internal pull-up is enabled to avoid false edge detection as there is no external pull-up on the SAM L11 Xplained Pro Evaluation Kit.

EIC pin configuration

As per the application project design, the User Button must be configured in Secure mode and by default, this pin is configured as a Secure mode pin by MCC.

Select the Project Graph tab

Under the Device Resources tab, expand Harmony > Peripherals > EIC.

Select and double-click on EIC to add the EIC module to the project.

Select and double click on EIC to add the EIC module to the project

Configure the EIC block to generate an interrupt every time the user presses the SW0 switch and enable filter functionality to avoid electrical noise on the switch pin as shown in the following image.

Configure the EIC block

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Configure LED Pin in Secure Mode

In this step, the user LED will be configured as per the USER_LED shown in the SAM L11 Xplained Pro Evaluation Kit schematic. See the following image.

User LED schematic

Select the Pin Settings tab and then scroll down to 8 in the Pin Number column and configure the PORT pin PA07 as an output pin for LED functionality. See the following image.

LED pin configuration

  • The LED on the SAM L11 Xplained Pro board is active low. Configure the LED in the default OFF state by configuring the latch value to logic High.
  • As per the application project design, the User LED must be configured in Secure mode and by default, this pin is configured as a Secure mode pin by MCC.

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Rename the Default main File

Under the Project Graph tab, click on System, and give a name of your liking to the default template main file generated by the MCC

Main file name setup

  • The name of the default main.c is changed to main_l11.c to indicate that the referred main.c is for the SAM L11 Arm® TrustZone® getting started training module.
  • The default template main file name of both Secure and Non-Secure projects will be changed to main_l11.c.

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