Step 2: Configuration of SysTick Timer
Configure SysTick Timer
After launching MPLAB Code Configurator (MCC), select System in the Project Graph. The configuration options will appear on the right side of the interface. Expand Cortex-M23 Configuration > SysTick, then select Enable SysTick.
Configure SERCOM3 as USART Peripheral
After configuring SysTick, navigate to the Device Resource tab. In the Device Resource panel, expand Libraries > Harmony > Peripherals > SERCOM > SERCOM3. To add the SERCOM3 Peripheral Library (PLIB) to the project graph, either double-click on SERCOM3 or drag and drop it into the Project Graph area.
Right-click the Yellow UART diamond icon in SERCOM3 and select STDIO from the Available Consumers drop-down menu. This setup enables functions such as printf() to transmit data to the terminal.
Select the SERCOM3 peripheral library in the Project Graph. The configuration options will be displayed on the right side of the interface. By default, the SERCOM operation mode is set to USART communication. Configure SERCOM PAD [1] as the Receive Pinout.
Open the Pin Configuration tabs by clicking Project Graph > Plugins > Pin Configuration.
Select the MCC Pin Settings tab and sort the entries by Ports, as shown in the accompanying image.
Scroll down to pin number 7 (Pin ID: PB08) and pin number 8 (Pin ID: PB09). Configure PB08 as SERCOM3_PAD0 and PB09 as SERCOM3_PAD1. Set the Security Mode to NON-SECURE.
Arm® TrustZone® for Armv8-M
Go to Plugins drop-down options in Project Graph and then select Arm TrustZone for Armv8-M.
In the Peripheral Configuration > Peripherals section of the Arm TrustZone for Armv8-M window, configure the required peripherals to operate in Non-Secure mode. Set SERCOM3 to the Non-Secure configuration.
