Generic keyboard emulation using Arduino Leonardo

Question

I am trying to use an Arduino Leonardo for keyboard emulation since that is one of its advertised features. I have been playing with the Leonardo and wrote a very simple sketch based off the Blink example.

// Pin 13 has an LED connected on most Arduino boards.
int led = 13;

// The setup routine runs once when you press reset:
void setup()
{
    // Initialize the digital pin as an output.
    pinMode(led, OUTPUT);
}

// The loop routine runs over and over again forever:
void loop()
{
    delay(5000);              // Wait for five seconds
    digitalWrite(led, HIGH);  // Turn the LED on (HIGH is the voltage level)
    delay(100);               // Wait for a secondA
    digitalWrite(led, LOW);   // Turn the LED off by making the voltage LOW
    Keyboard.write('A');      // Write an A using keyboard emulator
}

Now this example works great on my Windows XP machine. It is recognized as a generic HID keyboard and will type an 'A' every five seconds.

The targeted environment is running DOS so to my knowledge I need to get the Arduino Leonardo recognized by the BIOS on this machine, which it is not and it does not type the 'A' in DOS.

I have been making modifications to the USB device descriptor of the Leonardo, trying to make it match a Dell L100 as much as possible. The modifications I've made haven't helped, and I suspect it is because the Leonardo is a composite device which exposes the serial communication, keyboard emulation, and mouse emulation on the same USB port. The source code for the USB descriptors/configuration is available to be edited and is located at:

• Arduino_Installation\hardware\arduino\cores\arduino\HID.cpp
• Arduino_Installation\hardware\arduino\cores\arduino\USBDesc.h
• Arduino_Installation\hardware\arduino\cores\arduino\USBCore.h
• Arduino_Installation\hardware\arduino\cores\arduino\USBCore.cpp

The following is a dump from USB Device Viewer for the Leonardo:

[Port3]  :  USB Composite Device

          ---===>Device Information<===---
English product name: "Arduino Leonardo"

ConnectionStatus:
Current Config Value:              0x01  -> Device Bus Speed: Full
Device Address:                    0x03
Open Pipes:                           4

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x81  -> Direction: IN - EndpointID: 1
bmAttributes:                      0x03  -> Interrupt Transfer Type
wMaxPacketSize:                  0x0010 = 0x10 bytes
bInterval:                         0x40

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x02  -> Direction: OUT - EndpointID: 2
bmAttributes:                      0x02  -> Bulk Transfer Type
wMaxPacketSize:                  0x0040 = 0x40 bytes
bInterval:                         0x00

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x83  -> Direction: IN - EndpointID: 3
bmAttributes:                      0x02  -> Bulk Transfer Type
wMaxPacketSize:                  0x0040 = 0x40 bytes
bInterval:                         0x00

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x84  -> Direction: IN - EndpointID: 4
bmAttributes:                      0x03  -> Interrupt Transfer Type
wMaxPacketSize:                  0x0040 = 0x40 bytes
bInterval:                         0x01

          ===>Device Descriptor<===
bLength:                           0x12
bDescriptorType:                   0x01
bcdUSB:                          0x0110
bDeviceClass:                      0x00
*!*ERROR: device class should be Multi-interface Function 0xEF
          When IAD descriptor is used
bDeviceSubClass:                   0x00
*!*ERROR: device SubClass should be USB Common Sub Class 2
          When IAD descriptor is used
bDeviceProtocol:                   0x00
*!*ERROR: device Protocol should be USB IAD Protocol 1
          When IAD descriptor is used
bMaxPacketSize0:                   0x40 = (64) Bytes
idVendor:                        0x2341 = Vendor ID not listed with USB.org as of 03-19-2008
idProduct:                       0x8036
bcdDevice:                       0x0100
iManufacturer:                     0x01
     English (United States)  "Arduino LLC"
iProduct:                          0x02
     English (United States)  "Arduino Leonardo"
iSerialNumber:                     0x00
bNumConfigurations:                0x01

          ===>Configuration Descriptor<===
bLength:                           0x09
bDescriptorType:                   0x02
wTotalLength:                    0x0064  -> Validated
bNumInterfaces:                    0x03
bConfigurationValue:               0x01
iConfiguration:                    0x00
bmAttributes:                      0x80  -> Bus Powered
MaxPower:                          0xFA = 500 mA

          ===>IAD Descriptor<===
bLength:                           0x08
bDescriptorType:                   0x0B
bFirstInterface:                   0x00
bInterfaceCount:                   0x02
bFunctionClass:                    0x02  -> This is Communications (CDC Control) USB Device Interface Class
bFunctionSubClass:                 0x01
bFunctionProtocol:                 0x01
iFunction:                         0x00

          ===>Interface Descriptor<===
bLength:                           0x09
bDescriptorType:                   0x04
bInterfaceNumber:                  0x00
bAlternateSetting:                 0x00
bNumEndpoints:                     0x01
bInterfaceClass:                   0x02  -> This is Communications (CDC Control) USB Device Interface Class
bInterfaceSubClass:                0x01
bInterfaceProtocol:                0x00
CAUTION:  This may be an invalid bInterfaceProtocol
iInterface:                        0x00
  -> This is a Communications (CDC Control) USB Device Interface Class

          ===>Descriptor Hex Dump<===
bLength:                           0x05
bDescriptorType:                   0x24
05 24 00 10 01
  -> This is a Communications (CDC Control) USB Device Interface Class

          ===>Descriptor Hex Dump<===
bLength:                           0x05
bDescriptorType:                   0x24
05 24 01 01 01
  -> This is a Communications (CDC Control) USB Device Interface Class

          ===>Descriptor Hex Dump<===
bLength:                           0x04
bDescriptorType:                   0x24
04 24 02 06
  -> This is a Communications (CDC Control) USB Device Interface Class

          ===>Descriptor Hex Dump<===
bLength:                           0x05
bDescriptorType:                   0x24
05 24 06 00 01

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x81  -> Direction: IN - EndpointID: 1
bmAttributes:                      0x03  -> Interrupt Transfer Type
wMaxPacketSize:                  0x0010 = 0x10 bytes
bInterval:                         0x40

          ===>Interface Descriptor<===
bLength:                           0x09
bDescriptorType:                   0x04
bInterfaceNumber:                  0x01
bAlternateSetting:                 0x00
bNumEndpoints:                     0x02
bInterfaceClass:                   0x0A  -> This is a CDC Data USB Device Interface Class
bInterfaceSubClass:                0x01
bInterfaceProtocol:                0x00
CAUTION:  This may be an invalid bInterfaceProtocol
iInterface:                        0x00

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x02  -> Direction: OUT - EndpointID: 2
bmAttributes:                      0x02  -> Bulk Transfer Type
wMaxPacketSize:                  0x0040 = 0x40 bytes
bInterval:                         0x00

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x83  -> Direction: IN - EndpointID: 3
bmAttributes:                      0x02  -> Bulk Transfer Type
wMaxPacketSize:                  0x0040 = 0x40 bytes
bInterval:                         0x00

          ===>Interface Descriptor<===
bLength:                           0x09
bDescriptorType:                   0x04
bInterfaceNumber:                  0x02
bAlternateSetting:                 0x00
bNumEndpoints:                     0x01
bInterfaceClass:                   0x03  -> HID Interface Class
bInterfaceSubClass:                0x01
bInterfaceProtocol:                0x00
CAUTION:  This may be an invalid bInterfaceProtocol
iInterface:                        0x00

          ===>HID Descriptor<===
bLength:                           0x09
bDescriptorType:                   0x21
bcdHID:                          0x0101
bCountryCode:                      0x00
bNumDescriptors:                   0x01
bDescriptorType:                   0x22
wDescriptorLength:               0x0065

          ===>Endpoint Descriptor<===
bLength:                           0x07
bDescriptorType:                   0x05
bEndpointAddress:                  0x84  -> Direction: IN - EndpointID: 4
bmAttributes:                      0x03  -> Interrupt Transfer Type
wMaxPacketSize:                  0x0040 = 0x40 bytes
bInterval:                         0x01

How could I get this Leonardo recognized by a BIOS as a generic keyboard?

Answer 1

Arduino does not support the boot protocol. I have started using Teensy (which is Arduino compatible), and it works pretty well.