LED 2

Let's now make the led toggle every half a second.

As usual, we will use a delay function to do this. But initialising the delay function requires the current CPU frequency. The ASF has a clock control module driver. We can use a function from this which will return the value of current CPU frequency.

To add the clock control driver

• Start the ASF Wizard.
• Type clock in the search box and select System Clock Control.
• Press Add and then Apply.

Note that when a new driver is added through ASF Wizard, new files are found in the Solution Explorer window.

Every driver must be initialised before using. Type

sysclk_init();

It better to use the auto complete by selecting the required suggestion from the pop-up and pressing Enter.

Now add the delay driver using the ASF Wizard.

We can get the current CPU frequency using the function

sysclk_get_cpu_hz()

Initialise the delay driver by typing

delay_init(sysclk_get_cpu_hz())

To make the LED toggle, use the following code

gpio_toggle_pin(LED0_GPIO);
delay_ms(500);

in the while loop. Use any delay function that you prefer.

Click here for project code