How to: LED Control

Controlling LED diode integrated with Core module is like printing Hello world. In this tutorial, we will go through available functions for controlling LED diode provided by SDK.

Tip

Visit documentation for this SDK module

Requirements

Example

First, an instance of led is needed. You can achieve this by adding this line:

twr_led_t led;

Now, we can decide between two options how to control the diode.

  1. synchronous way: “LED ON -> wait -> LED OFF -> REPEAT”. This way is similar to using delay() functions with Arduino.

  2. asynchronous way (the right way). HARDWARIO TOWER SDK has been built with goal to provide simple-to-use but robust tasking mechanism, which will be completely asynchronous.

    This is the best way to program your microcontroller. You are not limited to doing one thing all the time and power consumption can be decreased (because controller sleeps most of the time).

Asynchronous LED blinking

  1. We need to tell to the SDK, that we are going to use on-board LED

twr_led_init(&led, TWR_GPIO_LED, false, false);

  1. Now we use function that will tell the Scheduler to plan toggling of LED mode periodically.

twr_led_set_mode(&led, TWR_LED_MODE_BLINK);

Thanks to those simple lines, our microcontroller will toggle led mode periodically and between toggling, it can do whatever you want to do - measuring, sending data, …

Complete example of application.c file:

1#include <application.h>
2
3twr_led_t led;
4
5void application_init(void)
6{
7    twr_led_init(&led, TWR_GPIO_LED, false, false);
8    twr_led_set_mode(&led, TWR_LED_MODE_BLINK);
9}

Note

Function application_task is not used here - it is simply not needed. Scheduler takes care of entire blinking process: it toggles actual LED status, then makes the controller sleep, after defined time wakes it up and repeats entire process.

Predefined blinking patterns

Four blinking patterns are available in SDK. Ordered from slowest to fastest.

1TWR_LED_MODE_BLINK
2TWR_LED_MODE_BLINK_SLOW
3TWR_LED_MODE_BLINK_FAST
4TWR_LED_MODE_FLASH