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This article mainly introduces how to achieve flicker board LED in Beaglebone Black, which is very detailed and has a certain reference value. Friends who are interested must read it!

Flicker onboard LED

By the time you finish setting up your Beaglebone Black, you may already be looking forward to your first project. The following is to meet everyone's wishes, of course, this project is not an earth-shaking project, but everything always has a start. This project does not require additional electronics, which allows you to focus on programming. This also ensures that all the settings on your Beaglebone Black board are correct.

Gossip aside, our project is to write code to control Beaglebone Black's on-board LED. If you have previous programming experience, think of this project as a "Hello World" program for Beaglebone Black. We will finish the whole program from scratch, which will give you a preliminary feeling of writing BoneScript code in Cloud9 IDE.

Here is the code for flashing onboard LED:

Var b = require ('bonescript')

Var led = "USR3"

B.pinMode (led, b.OUTPUT)

Var state = b.LOW

B.digitalWrite (led, state)

SetInterval (toggle, 1000)

Function toggle () {

If (state = = b.LOW) state = b.HIGH

Else state = b.LOW

B.digitalWrite (led, state)

}

When writing code in BoneScript, we need to point the code to the BoneScript library to access the GPIO port and other functions of Beaglebone Black. So, our first line of code creates a variable (b) to introduce the library between the two parentheses into our code:

Var b = require ('bonescript')

The next logical snippet of the code is a variable that creates a reference to the onboard LED USR3:

Var led = "USR3"

In the above example, we call this variable led, which corresponds to the USR3 of the onboard LED.

The GPIO digital port on Beaglebone Black can be set as input or output port. So, in our code, we need to tell Beaglebone Black that we want onboard LED as output. To do this, we need to use a function named pinMode and take the port we expect as its argument; in this example, we use the variable led and set it to output with the variable b.OUTPUT:

B.pinMode (led, b.OUTPUT)

In this code, we create a loop that collects the LED state. In this loop, you switch the state of the LED between on and off. To complete this, we also need to set an additional variable state, which is used to hold the state of LED at this time; at the beginning, we should give it an initial value, here is b.LOW, which corresponds to "off":

Var state = b.LOW

Now we can set the state of LED and set it to state. To do this, you need to use the digitalWrite () function and take the GPIO port and state (on and off) of the desired operation as parameters:

B.digitalWrite (led, state)

After the initial state of LED is set, we need to trigger LED to light up and turn off, that is, to change the state of the state variable. We use the setInterval () function to set the interval for this change to 1000 milliseconds, or 1 second. When the interval arrives, we call the toggle () function:

SetInterval (toggle, 1000)

Now we need to create a function called toggle to be called by the setInterval () function, which will be called every 1000 milliseconds. The function of this function is to switch the state of LED, that is, to switch between HIGH and LOW. Since there are only these two states, the easiest way is to if. Else judges that it accepts a conditional statement and executes different statements depending on whether the conditional statement is TRUE or FALSE:

If (conditional statement) {

Execute when the conditional statement is TRUE

} else {

Execute when a conditional statement is not TRUE

}

In our function, we should check whether the value of the state variable is equal to LOW. If so, we set state to HIGH;. If not, execute the statement after else and set state to LOW. After setting up, use the digitalWrite () function to apply this state to the LED:

Function toggle () {

If (state = = b.LOW) state = b.HIGH

Else state = b.LOW

B.digitalWrite (led, state)

}

By executing the above code, we can see that LED USR3 flashes at intervals of 1000 millionths of a second. If you want to change the flicker frequency, you can modify this statement:

SetInterval (toggle, 1000)

It's best to give it a try.

The above is all the contents of the article "how to achieve scintillation on-board LED in Beaglebone Black". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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