4 Creating the LED Blink Application

Open the Clock Configuration tool from the Plugins section in the Project Graph to verify that the system clock is set to 48 MHz.

The visual interface shows clock sources and dividers, making it easy to check or adjust settings.

SysTick is a built-in timer that allows the application to track time and create precise delays which can be used for blinking an LED. It operates entirely in hardware, so no manual software loops are needed.

To enable SysTick:

1. In the Project Graph, select the System module.

   

2. In the Configuration Options panel, expand Cortex M0+ Configuration.
3. Enable the SysTick option.

   

Before configuring the LED in software, we need to identify which pin it is connected to on the Curiosity Nano. According to the Curiosity Nano User Guide, which can be found in the Kit Window of MPLAB X IDE or on the Curiosity Nano landing page, the onboard LED is connected to pin PB17. This is the pin we will configure as a digital output.

After you finish configuring your project, MCC takes care of generating all the code you need to get started. This includes:

• Configuration bits
• Peripheral setup code
• Easy-to-use functions (called APIs) for things like toggling LEDs or adding delays

To generate code in MCC, click the Generate button in the Project Resources tab in MCC.

You can find these files in the Projects tab, under your project’s Header Files and Source Files folders.

If you Ctrl+Click on any of these function names, you’ll jump straight to the actual code that MCC generated (found in the matching source file, like plib_systick.c). This is helpful if you want to see how a function works or what it does behind the scenes.

This is one of the main benefits of using MCC: It gives you a working starting point without having to write all the setup code yourself.

Now that configuration is complete, it’s time to write the application logic in main.c to toggle the onboard LED with a fixed delay. We’ll use functions that MCC automatically generated based on our earlier setup, no manual register-level coding needed.

MCC Generated APIs Used:

• SYSTICK_TimerStart()
  • Declared in: plib_systick.h
  • Defined in: plib_systick.c
  • Purpose: Starts the SysTick timer so that delay functions can work
• LED_Toggle()
  • Declared in: plib_port.h
  • Defined in: plib_port.c
  • Purpose: Toggles the pin we labeled LED in the Pin Manager (PB17). MCC generated this function based on that custom name.
• SYSTICK_DelayMs(x)
  • Declared in: plib_systick.h
  • Defined in: plib_systick.c
  • Purpose: Delays code execution for a specified number of milliseconds

int main(void) {
    /* Initialize all modules */
    SYS_Initialize(NULL);
    SYSTICK_TimerStart();
    while (true) {
        /* Maintain state machines of all polled MPLAB Harmony modules. */
        SYS_Tasks();
        LED_Toggle();
        SYSTICK_DelayMs(500);
    }

    /* Execution should not come here during normal operation */

    return ( EXIT_FAILURE);
}
 

Now that your application code is written and MCC has generated all the supporting files, it's time to compile and load the project onto the Curiosity Nano.

Build the Project: Click the Clean and Build icon on the MPLAB X IDE toolbar. This compiles the code and confirms everything is configured correctly.

Check the Output window to ensure the build is completed successfully.

Program the Device: Make sure the Curiosity Nano is connected via USB. Click the Make and Program Device icon on the MPLAB X IDE toolbar to flash the firmware onto the board.

Check the Output window to ensure Programming was completed successfully.

Once successful, the onboard LED will begin blinking with a 500 ms delay.

Now that your LED is blinking, you’ve successfully created a simple embedded application using MPLAB Harmony v3 and the PIC32CM JH/GV Curiosity Nano. Along the way, you:

• Explored the Harmony v3 MCC interface
• Used graphical tools to configure peripherals like SysTick and GPIO
• Leveraged MCC’s auto-generated APIs to write application code without touching a single register
• Built and programmed the project in just a few clicks

This is just the beginning — the same approach can be used to configure UART, I2C, Timers and more. Harmony v3 makes it easy to scale your application as it grows in complexity.