Press Multiple Keys when Using Arduino Uno As HID Keyboard

Projects Programming
1

I followed this tutorial on how to set up arduino uno as an HID keyboard device, while some parts required more research, it was fairly straightforwards. I got it set up, but when I analyzed the key events, i noticed an anomaly:

keydown keyCode=71 (G) which=71 (G) charCode=0
keypress keyCode=0 which=103 (g) charCode=103 (g)
keyup keyCode=71 (G) which=71 (G) charCode=0
keydown keyCode=70 (F) which=70 (F) charCode=0
keypress keyCode=0 which=102 (f) charCode=102 (f)

(This was repeated on every loop())

In pressing a key, the previously pressed key, while not actually released, is read to have been released.

Here is my code (modified from tutorial):

uint8_t buf[8] = { 
  0 }; /* Keyboard report buffer */
 
setup() 
{
  Serial.begin(9600);
  delay(200);
}
 
void loop() 
{
  delay(2000);
  buf[2] = 10;
  Serial.write(buf, 8);
  buf[2] = 9;
  Serial.write(buf, 8);
  releaseKey();
}
 
void releaseKey() 
{
  buf[0] = 0;
  buf[2] = 0;
  Serial.write(buf, 8); // Release key 
}

So I wanted to know if there was a way to have multiple keys (say, F and G) be pressed together or separately, and stay pressed together. Then release them one at a time.

2

First please get rid of the smiley faces by using code tags instead of quote tags in your post.

3

Your example does not do press but write. Assuming it works the same as on the HID files the write function does this:

size_t Keyboard_::write(uint8_t c)
{	
	uint8_t p = press(c);		// Keydown
	uint8_t r = release(c);		// Keyup
	return (p);					// just return the result of press() since release() almost always returns 1
}

So you can see that write does a press and a release.

4

It doesn't, if I set it to send only one key (even repeating it), there is no keyup event until I halt the program (and even then there is only one).

5 
uint8_t buf[8] = {

0 }; /* Keyboard report buffer */

void [color=#CC6600]setup/color
{
  Serial.[color=#CC6600]begin/color;
  [color=#CC6600]randomSeed/color;
  [color=#CC6600]delay/color;
}

?

It doesn't, if I set it to send only one key (even repeating it), there is no keyup event until I halt the program (and even then there is only one).

Which processor on the Uno are you using for this? The Atmega328P or the Atmega16u4?

6

the Atmega16u2, on arduino uno r3

7

What board do you have set in the IDE? What library(s) are you using for the keyboard access?

8

The IDE is set to Ardiono Uno, as for librarys, all my code is there, and I am flashing the arduino-keyboard-0.3.hex to make it show up as an HID.