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USBKeyboard

Table of Contents

  1. Hello World
  2. API
  3. More examples
  4. Related

The USBKeyboard interface is used to emulate a keyboard over the USB port. You can type strings and send keycodes, send keys with modifiers (e.g. CTRL + 's'), function keys and also the media control keys

The USB connector should be attached to p31 (D+), p32 (D-) and GND. You can also connect the USB power to VIN to power the mbed when connected.

Hello World

USBKeyboard Hello World

#include "mbed.h"
#include "USBKeyboard.h"

//LED1: NUM_LOCK
//LED2: CAPS_LOCK
//LED3: SCROLL_LOCK
BusOut leds(LED1, LED2, LED3);

//USBKeyboard
USBKeyboard keyboard;

int main(void) {
    while (1) {
        keyboard.mediaControl(KEY_VOLUME_DOWN);
        keyboard.printf("Hello World from Mbed\r\n");
        keyboard.keyCode('s', KEY_CTRL);
        keyboard.keyCode(KEY_CAPS_LOCK);
        wait(1);
        leds = keyboard.lockStatus();
    }
}

Import programUSBKeyboard_HelloWorld

USBKeyboard Hello World

Last commit 01 Mar 2013 by Samuel Mokrani

API

Import library
USBDevice - USBKeyboard Class Reference

Public Member Functions

USBKeyboard (uint16_t vendor_id=0x1235, uint16_t product_id=0x0050, uint16_t product_release=0x0001)
Constructor.
bool keyCode (uint8_t key, uint8_t modifier=0)
To send a character defined by a modifier(CTRL, SHIFT, ALT) and the key.
virtual int _putc (int c)
Send a character.
bool mediaControl (MEDIA_KEY key)
Control media keys.
uint8_t lockStatus ()
Read status of lock keys.
bool send (HID_REPORT *report)
Send a Report.
bool sendNB (HID_REPORT *report)
Send a Report.
bool read (HID_REPORT *report)
Read a report: blocking.
bool readNB (HID_REPORT *report)
Read a report: non blocking.

More examples

Program which controls sound and tracks of your playlist with switches:

USBKeyboard and media keys

#include "mbed.h"
#include "USBKeyboard.h"

USBKeyboard keyboard;

//Bus of buttons
BusInOut buttons(p21, p22, p23, p24, p25, p26, p29);

int main(void) {
    uint8_t p_bus = 0;

    while (1) {
        //if the bus of buttons has changed, send a report
        if (buttons.read() != p_bus) {
            p_bus = buttons.read();
            if(p_bus & 0x01)
               keyboard.mediaControl(KEY_MUTE);
            if(p_bus & 0x02)
               keyboard.mediaControl(KEY_VOLUME_DOWN);
            if(p_bus & 0x04)
               keyboard.mediaControl(KEY_VOLUME_UP);
            if(p_bus & 0x08)
               keyboard.mediaControl(KEY_NEXT_TRACK);
            if(p_bus & 0x10)
               keyboard.mediaControl(KEY_PLAY_PAUSE);
            if(p_bus & 0x20)
               keyboard.mediaControl(KEY_PREVIOUS_TRACK);
            if(p_bus & 0x40)
               keyboard.printf("Hello World\r\n");
        }
        wait(0.01);
    }
}
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