MenuYou know that there are two bare minimum functions called setup and loop in a sketch. But there are many more functions which are very useful while programming complex sketches. Have a look at the below sketch, which opens up notepad and types "Hello World" in it.
Code:
void setup()
{
delay(5000);
Keyboard.set_modifier(MODIFIERKEY_RIGHT_GUI);
Keyboard.set_key1(KEY_R);
Keyboard.send_now();
delay(500);
Keyboard.set_modifier(0);
Keyboard.set_key1(0);
Keyboard.send_now();
Keyboard.print("notepad");
Keyboard.set_key1(KEY_ENTER);
Keyboard.send_now();
Keyboard.set_key1(0);
Keyboard.send_now();
delay(2000);
Keyboard.print("Hello World");
}
void loop()
{
}
1. Press "Windows key + R"
2. Release "Windows key + R"
2. Type "notepad" when the run prompt opens up.
3. Press Enter.
4. Release Enter
Easy one. Now, if you map these steps to the sketch above you will find that the sketch is doing nothing but "simulating" your keystrokes. Let's have a look at the sketch again with comments
Code:
void setup()
{
delay(5000); //Delay required for OS to connect the device properly
Keyboard.set_modifier(MODIFIERKEY_RIGHT_GUI); //Tell Teensy to press Windows key
Keyboard.set_key1(KEY_R); //Tell Teensy to press R
Keyboard.send_now(); //Press "Windows key + R"
delay(500); //Wait for half second
Keyboard.set_modifier(0); //Tell Teensy to release Windows key
Keyboard.set_key1(0); //Tell Teensy to release R
Keyboard.send_now(); //Release "Windows key + R"
//Teensy should open a run prompt now
Keyboard.print("notepad"); //Type notepad in the run prompt
Keyboard.set_key1(KEY_ENTER); //Tell Teensy to press Enter key
Keyboard.send_now(); //Press Enter
Keyboard.set_key1(0); //Tell Teensy to release Enter
Keyboard.send_now(); //Release Enter
delay(2000); //Wait for notepad to open
Keyboard.print("Hello World"); //Type Hello World in notepad
}
void loop()
{
}
delay() delays the execution of sketch by Teensy for given milliseconds. delay(5000) means delaying the execution for 5 seconds.
Keyboard.set_modifier sets a modifier key. There are four modifier keys
Name Function
MODIFIERKEY_CTRL Control Key
MODIFIERKEY_SHIFT Shift Key
MODIFIERKEY_ALT Alt Key
MODIFIERKEY_GUI Windows (PC) or Clover (Mac)
Table Courtesy: Teensyduino: Using USB Keyboard with Teensy on the Arduino IDE
Note that I said it "sets" the modifier key. To send the key you need Keyboard.send_now() which sends all the "set" keys. We used Keyboard.setkey1 for setting the "R" key and then sent them together using Keyboard.send_now().
As per great documentation here at pjrc.com USB keyboard can have up-to 6 normal keys and 4 modifier keys. A complete table of codes for all normal keys could be found on the same page.
So we pressed the "Windows keys + R" by setting and sending the keys. Now to release them we need to set them to 0 and send them again. That is what we have done in above sketch by using Keyboard.set_modifier(0), Keyboard.setkey1(0) and Keyboard.send_now().
Rest of the sketch is easy to understand and needs no explanation.
In the next post we will have a look at Kautilya. Please leave comments and feedback.
Read Part I here- http://www.garage4hackers.com/conten...o-install.html
Part-II-http://www.garage4hackers.com/conten...llo-world.html
Part-IV-http://www.garage4hackers.com/conten...-kautilya.html
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