Note: This tutorial assumes that you have completed the previous tutorials: Using rosserial with AVR and UART.
(!) Please ask about problems and questions regarding this tutorial on answers.ros.org. Don't forget to include in your question the link to this page, the versions of your OS & ROS, and also add appropriate tags.

Using rosserial with AVR and USB

Description: This tutorial will show you how to run rosserial on an AVR that supports USB.

Keywords: rosserial, rosserial_client, AVR, embedded, microcontroller, USB, LUFA

Tutorial Level: INTERMEDIATE

Source Code

You can download the full source code for this tutorial here: https://github.com/mrjogo/rosserial_avr_tutorial/tree/lufa

Prerequisites

This tutorial will build directly on the code from Using rosserial with AVR and UART. However, you will not need the avr_uart module, and we will replace Atmega32u4Hardware.h and the Makefile. You can delete the unnecessary files with the following command:

roscd rosserial_avr_tutorial && rm avr_uart.h avr_uart.c Atmega32u4Hardware.h Makefile

This tutorial also uses the Atmega32u4, but instead of the UART, we are now going to use the built-in USB support (you can use other AVR chips that support USB by changing the data registers and the Makefile). The tutorial was built using the Adafruit Atmega32u4 Breakout Board, but if you want to build your own breakout circuitry, Adafruit has posted the schematics.

Adding USB Support

Getting LUFA

The Lightweight USB Framework for AVRs (LUFA) is a library that makes it easier to use the AVR's USB capabilities. It is released under the MIT License, and you can download it from http://code.google.com/p/lufa-lib/downloads/list. Unzip the archive and put the LUFA subdirectory in rosserial_avr_tutorial/src.

Setting the USB Descriptors

USB is more complex than UART, and the computer needs to know some information about our AVR. This is acomplished through Descriptors. We will adapt the Descriptors files from the VirtualSerial LUFA demo:

Descriptors.h

/*
             LUFA Library
     Copyright (C) Dean Camera, 2011.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/

/* >> Modified for use with ROS rosserial_client tutorial << */

/*
  Copyright 2011  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, distribute, and sell this
  software and its documentation for any purpose is hereby granted
  without fee, provided that the above copyright notice appear in
  all copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of the
  software without specific, written prior permission.

  The author disclaim all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/

/** \file
 *
 *  Header file for Descriptors.c.
 */

#ifndef _DESCRIPTORS_H_
#define _DESCRIPTORS_H_

        /* Includes: */
                #include <avr/pgmspace.h>

                #include <LUFA/Drivers/USB/USB.h>

        /* Macros: */
                /** Endpoint number of the CDC device-to-host notification IN endpoint. */
                #define CDC_NOTIFICATION_EPNUM         2

                /** Endpoint number of the CDC device-to-host data IN endpoint. */
                #define CDC_TX_EPNUM                   3

                /** Endpoint number of the CDC host-to-device data OUT endpoint. */
                #define CDC_RX_EPNUM                   4

                /** Size in bytes of the CDC device-to-host notification IN endpoint. */
                #define CDC_NOTIFICATION_EPSIZE        8

                /** Size in bytes of the CDC data IN and OUT endpoints. */
                #define CDC_TXRX_EPSIZE                16

        /* Type Defines: */
                /** Type define for the device configuration descriptor structure. This must be defined in the
                 *  application code, as the configuration descriptor contains several sub-descriptors which
                 *  vary between devices, and which describe the device's usage to the host.
                 */
                typedef struct
                {
                        USB_Descriptor_Configuration_Header_t    Config;

                        // CDC Control Interface
                        USB_Descriptor_Interface_t               CDC_CCI_Interface;
                        USB_CDC_Descriptor_FunctionalHeader_t    CDC_Functional_Header;
                        USB_CDC_Descriptor_FunctionalACM_t       CDC_Functional_ACM;
                        USB_CDC_Descriptor_FunctionalUnion_t     CDC_Functional_Union;
                        USB_Descriptor_Endpoint_t                CDC_NotificationEndpoint;

                        // CDC Data Interface
                        USB_Descriptor_Interface_t               CDC_DCI_Interface;
                        USB_Descriptor_Endpoint_t                CDC_DataOutEndpoint;
                        USB_Descriptor_Endpoint_t                CDC_DataInEndpoint;
                } USB_Descriptor_Configuration_t;

        /* Function Prototypes: */
                uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue,
                                                    const uint8_t wIndex,
                                                    const void** const DescriptorAddress)
                                                    ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(3);

#endif

Descriptors.c

/*
             LUFA Library
     Copyright (C) Dean Camera, 2011.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/

/* >> Modified for use with ROS rosserial_client tutorial << */

/*
  Copyright 2011  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, distribute, and sell this
  software and its documentation for any purpose is hereby granted
  without fee, provided that the above copyright notice appear in
  all copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of the
  software without specific, written prior permission.

  The author disclaim all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/

/** \file
 *
 *  USB Device Descriptors, for library use when in USB device mode. Descriptors are special
 *  computer-readable structures which the host requests upon device enumeration, to determine
 *  the device's capabilities and functions.
 */

#include "Descriptors.h"

/* On some devices, there is a factory set internal serial number which can be automatically sent to the host as
 * the device's serial number when the Device Descriptor's .SerialNumStrIndex entry is set to USE_INTERNAL_SERIAL.
 * This allows the host to track a device across insertions on different ports, allowing them to retain allocated
 * resources like COM port numbers and drivers. On demos using this feature, give a warning on unsupported devices
 * so that the user can supply their own serial number descriptor instead or remove the USE_INTERNAL_SERIAL value
 * from the Device Descriptor (forcing the host to generate a serial number for each device from the VID, PID and
 * port location).
 */
#if (USE_INTERNAL_SERIAL == NO_DESCRIPTOR)
        #warning USE_INTERNAL_SERIAL is not available on this AVR - please manually construct a device serial descriptor.
#endif

/** Device descriptor structure. This descriptor, located in FLASH memory, describes the overall
 *  device characteristics, including the supported USB version, control endpoint size and the
 *  number of device configurations. The descriptor is read out by the USB host when the enumeration
 *  process begins.
 */
const USB_Descriptor_Device_t PROGMEM DeviceDescriptor =
{
        .Header                 = {.Size = sizeof(USB_Descriptor_Device_t), .Type = DTYPE_Device},

        .USBSpecification       = VERSION_BCD(01.10),
        .Class                  = CDC_CSCP_CDCClass,
        .SubClass               = CDC_CSCP_NoSpecificSubclass,
        .Protocol               = CDC_CSCP_NoSpecificProtocol,

        .Endpoint0Size          = FIXED_CONTROL_ENDPOINT_SIZE,

        .VendorID               = 0x03EB,
        .ProductID              = 0x2044,
        .ReleaseNumber          = VERSION_BCD(00.01),

        .ManufacturerStrIndex   = 0x01,
        .ProductStrIndex        = 0x02,
        .SerialNumStrIndex      = USE_INTERNAL_SERIAL,

        .NumberOfConfigurations = FIXED_NUM_CONFIGURATIONS
};

/** Configuration descriptor structure. This descriptor, located in FLASH memory, describes the usage
 *  of the device in one of its supported configurations, including information about any device interfaces
 *  and endpoints. The descriptor is read out by the USB host during the enumeration process when selecting
 *  a configuration so that the host may correctly communicate with the USB device.
 */
const USB_Descriptor_Configuration_t PROGMEM ConfigurationDescriptor =
{
        .Config =
                {
                        .Header                 = {.Size = sizeof(USB_Descriptor_Configuration_Header_t), .Type = DTYPE_Configuration},

                        .TotalConfigurationSize = sizeof(USB_Descriptor_Configuration_t),
                        .TotalInterfaces        = 2,

                        .ConfigurationNumber    = 1,
                        .ConfigurationStrIndex  = NO_DESCRIPTOR,

                        .ConfigAttributes       = (USB_CONFIG_ATTR_BUSPOWERED | USB_CONFIG_ATTR_SELFPOWERED),

                        .MaxPowerConsumption    = USB_CONFIG_POWER_MA(100)
                },

        .CDC_CCI_Interface =
                {
                        .Header                 = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},

                        .InterfaceNumber        = 0,
                        .AlternateSetting       = 0,

                        .TotalEndpoints         = 1,

                        .Class                  = CDC_CSCP_CDCClass,
                        .SubClass               = CDC_CSCP_ACMSubclass,
                        .Protocol               = CDC_CSCP_ATCommandProtocol,

                        .InterfaceStrIndex      = NO_DESCRIPTOR
                },

        .CDC_Functional_Header =
                {
                        .Header                 = {.Size = sizeof(USB_CDC_Descriptor_FunctionalHeader_t), .Type = DTYPE_CSInterface},
                        .Subtype                = CDC_DSUBTYPE_CSInterface_Header,

                        .CDCSpecification       = VERSION_BCD(01.10),
                },

        .CDC_Functional_ACM =
                {
                        .Header                 = {.Size = sizeof(USB_CDC_Descriptor_FunctionalACM_t), .Type = DTYPE_CSInterface},
                        .Subtype                = CDC_DSUBTYPE_CSInterface_ACM,

                        .Capabilities           = 0x06,
                },

        .CDC_Functional_Union =
                {
                        .Header                 = {.Size = sizeof(USB_CDC_Descriptor_FunctionalUnion_t), .Type = DTYPE_CSInterface},
                        .Subtype                = CDC_DSUBTYPE_CSInterface_Union,

                        .MasterInterfaceNumber  = 0,
                        .SlaveInterfaceNumber   = 1,
                },

        .CDC_NotificationEndpoint =
                {
                        .Header                 = {.Size = sizeof(USB_Descriptor_Endpoint_t), .Type = DTYPE_Endpoint},

                        .EndpointAddress        = (ENDPOINT_DIR_IN | CDC_NOTIFICATION_EPNUM),
                        .Attributes             = (EP_TYPE_INTERRUPT | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
                        .EndpointSize           = CDC_NOTIFICATION_EPSIZE,
                        .PollingIntervalMS      = 0xFF
                },

        .CDC_DCI_Interface =
                {
                        .Header                 = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},

                        .InterfaceNumber        = 1,
                        .AlternateSetting       = 0,

                        .TotalEndpoints         = 2,

                        .Class                  = CDC_CSCP_CDCDataClass,
                        .SubClass               = CDC_CSCP_NoDataSubclass,
                        .Protocol               = CDC_CSCP_NoDataProtocol,

                        .InterfaceStrIndex      = NO_DESCRIPTOR
                },

        .CDC_DataOutEndpoint =
                {
                        .Header                 = {.Size = sizeof(USB_Descriptor_Endpoint_t), .Type = DTYPE_Endpoint},

                        .EndpointAddress        = (ENDPOINT_DIR_OUT | CDC_RX_EPNUM),
                        .Attributes             = (EP_TYPE_BULK | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
                        .EndpointSize           = CDC_TXRX_EPSIZE,
                        .PollingIntervalMS      = 0x01
                },

        .CDC_DataInEndpoint =
                {
                        .Header                 = {.Size = sizeof(USB_Descriptor_Endpoint_t), .Type = DTYPE_Endpoint},

                        .EndpointAddress        = (ENDPOINT_DIR_IN | CDC_TX_EPNUM),
                        .Attributes             = (EP_TYPE_BULK | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
                        .EndpointSize           = CDC_TXRX_EPSIZE,
                        .PollingIntervalMS      = 0x01
                }
};

/** Language descriptor structure. This descriptor, located in FLASH memory, is returned when the host requests
 *  the string descriptor with index 0 (the first index). It is actually an array of 16-bit integers, which indicate
 *  via the language ID table available at USB.org what languages the device supports for its string descriptors.
 */
const USB_Descriptor_String_t PROGMEM LanguageString =
{
        .Header                 = {.Size = USB_STRING_LEN(1), .Type = DTYPE_String},

        .UnicodeString          = {LANGUAGE_ID_ENG}
};

/** Manufacturer descriptor string. This is a Unicode string containing the manufacturer's details in human readable
 *  form, and is read out upon request by the host when the appropriate string ID is requested, listed in the Device
 *  Descriptor.
 */
const USB_Descriptor_String_t PROGMEM ManufacturerString =
{
        .Header                 = {.Size = USB_STRING_LEN(11), .Type = DTYPE_String},

        .UnicodeString          = L"ROS AVR Tutorial"
};

/** Product descriptor string. This is a Unicode string containing the product's details in human readable form,
 *  and is read out upon request by the host when the appropriate string ID is requested, listed in the Device
 *  Descriptor.
 */
const USB_Descriptor_String_t PROGMEM ProductString =
{
        .Header                 = {.Size = USB_STRING_LEN(13), .Type = DTYPE_String},

        .UnicodeString          = L"AVR rosserial_client"
};

/** This function is called by the library when in device mode, and must be overridden (see library "USB Descriptors"
 *  documentation) by the application code so that the address and size of a requested descriptor can be given
 *  to the USB library. When the device receives a Get Descriptor request on the control endpoint, this function
 *  is called so that the descriptor details can be passed back and the appropriate descriptor sent back to the
 *  USB host.
 */
uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue,
                                    const uint8_t wIndex,
                                    const void** const DescriptorAddress)
{
        const uint8_t  DescriptorType   = (wValue >> 8);
        const uint8_t  DescriptorNumber = (wValue & 0xFF);

        const void* Address = NULL;
        uint16_t    Size    = NO_DESCRIPTOR;

        switch (DescriptorType)
        {
                case DTYPE_Device:
                        Address = &DeviceDescriptor;
                        Size    = sizeof(USB_Descriptor_Device_t);
                        break;
                case DTYPE_Configuration:
                        Address = &ConfigurationDescriptor;
                        Size    = sizeof(USB_Descriptor_Configuration_t);
                        break;
                case DTYPE_String:
                        switch (DescriptorNumber)
                        {
                                case 0x00:
                                        Address = &LanguageString;
                                        Size    = pgm_read_byte(&LanguageString.Header.Size);
                                        break;
                                case 0x01:
                                        Address = &ManufacturerString;
                                        Size    = pgm_read_byte(&ManufacturerString.Header.Size);
                                        break;
                                case 0x02:
                                        Address = &ProductString;
                                        Size    = pgm_read_byte(&ProductString.Header.Size);
                                        break;
                        }

                        break;
        }

        *DescriptorAddress = Address;
        return Size;
}

There's too much here to go over everything (check out the LUFA documentation if you want to learn more), but there are a few parts you might need to change:

        .VendorID               = 0x03EB,
        .ProductID              = 0x2044,

The USB vendor and product ID. Vendor IDs are globally unique and assigned (for a price) by the USB-IF. The vendor can then assign a product ID to each USB products. The IDs used here are for the LUFA CDC demo (under the Atmel vendor ID), so make sure to change them if you intend to distribute your product.

        .UnicodeString          = L"ROS AVR Tutorial"

        .UnicodeString          = L"AVR rosserial_client"

These are the manufacturer and product string that will appear when the Atmega32u4 is connected to a PC.

Implementing rosserial_client

Defining the Hardware Interface

As in the previous tutorial, we have to implement the hardware class.

Atmega32u4Hardware.h

#ifndef _ATMEGA32U4_HARDWARE_H
#define _ATMEGA32U4_HARDWARE_H

extern "C" {
  #include "Descriptors.h"
  #include "avr_time.h"
  #include <LUFA/Drivers/USB/USB.h>
}


class Atmega32u4Hardware {
  public:
    Atmega32u4Hardware() {}

    void init() {
      avr_time_init();
      USB_Init();
      sei();
    }

    int read() {
      return CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
    }

    void write(uint8_t* data, int length) {
      CDC_Device_SendData(&VirtualSerial_CDC_Interface, (char *)data, (uint16_t)length);
    }

    unsigned long time() {
      return avr_time_now();
    }

    static USB_ClassInfo_CDC_Device_t VirtualSerial_CDC_Interface;
};

void EVENT_USB_Device_ConfigurationChanged(void);
void EVENT_USB_Device_ControlRequest(void);

#endif

Let's look at what has changed:

    void init() {
      avr_time_init();
      USB_Init();
      sei();
    }

The init method now calls LUFA's USB initialization function instaed of our UART initialization function.

    int read() {
      return CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
    }

CDC_Device_ReceiveByte is a LUFA function that returns a byte from the host on the specified interface, or a negative number if no byte is available.

    void write(uint8_t* data, int length) {
      CDC_Device_SendData(&VirtualSerial_CDC_Interface, (char *)data, (uint16_t)length);
    }

CDC_Device_SendData is a LUFA function that sends a buffer of data to the host on the specified USB interface.

    static USB_ClassInfo_CDC_Device_t VirtualSerial_CDC_Interface;

This is the USB virtual serial interface that we are going to do all of our communications over.

void EVENT_USB_Device_ConfigurationChanged(void);
void EVENT_USB_Device_ControlRequest(void);

These are event handlers for USB state changes that need to be implemented for LUFA to function properly. Both of the functions and VirtualSerial_CDC_Interface are defined in Atmega32u4Hardware.cpp:

Atmega32u4Hardware.cpp

#include "Atmega32u4Hardware.h"

USB_ClassInfo_CDC_Device_t Atmega32u4Hardware::VirtualSerial_CDC_Interface = {
  {
    0,

    CDC_TX_EPNUM,
    CDC_TXRX_EPSIZE,
    false,

    CDC_RX_EPNUM,
    CDC_TXRX_EPSIZE,
    false,

    CDC_NOTIFICATION_EPNUM,
    CDC_NOTIFICATION_EPSIZE,
    false,
  },
};

/** Event handler for the library USB Configuration Changed event. */

void EVENT_USB_Device_ConfigurationChanged(void)
{
  CDC_Device_ConfigureEndpoints(&Atmega32u4Hardware::VirtualSerial_CDC_Interface);
}



/** Event handler for the library USB Control Request reception event. */
void EVENT_USB_Device_ControlRequest(void)
{
  CDC_Device_ProcessControlRequest(&Atmega32u4Hardware::VirtualSerial_CDC_Interface);
}

Modifying avr_chatter.cpp

We have to make a small modification to avr_chatter.cpp in order for it to work with LUFA. In order for the USB to stay active, the following two LUFA functions must be called often (ie, in every iteration of the main while loop):

CDC_Device_USBTask(&Atmega32u4Hardware::VirtualSerial1_CDC_Interface);
USB_USBTask();

Add those functions after the call to nh.spinOnce() so that the code now looks like this (note also the new #include's at the top):

#include "ros.h"
#include "std_msgs/String.h"
#include "Atmega32u4Hardware.h"
// Include C headers (ie, non C++ headers) in this block
extern "C"
{
  #include <util/delay.h>
  #include <LUFA/Drivers/USB/USB.h>
}

// Needed for AVR to use virtual functions
extern "C" void __cxa_pure_virtual(void);
void __cxa_pure_virtual(void) {}

ros::NodeHandle nh;

std_msgs::String str_msg;
ros::Publisher chatter("chatter", &str_msg);

char hello[13] = "hello world!";

int main()
{
  uint32_t lasttime = 0UL;
  // Initialize ROS
  nh.initNode();
  nh.advertise(chatter);

  while(1)
  {
    // Send the message every second
    if(avr_time_now() - lasttime > 1000)
    {
      str_msg.data = hello;
      chatter.publish(&str_msg);
      lasttime = avr_time_now();
    }
    nh.spinOnce();
    // LUFA functions that need to be called frequently to keep USB alive
    CDC_Device_USBTask(&Atmega32u4Hardware::VirtualSerial_CDC_Interface);
    USB_USBTask();
  }

  return 0;
}

Makefile

The Makefile for this tutorial is adapted from the one used in the LUFA demos. It is very similar to the one in the previous tutorial (both are ultimately based on the WinAVR template), but ensures that the LUFA library builds properly.

Makefile

# Hey Emacs, this is a -*- makefile -*-
#----------------------------------------------------------------------------
# WinAVR Makefile Template written by Eric B. Weddington, Jörg Wunsch, et al.
#  >> Modified for use with the LUFA project. <<
#  >> Further modified for use with ROS rosserial_client tutorial <<
#
# Released to the Public Domain
#
# Additional material for this makefile was written by:
# Peter Fleury
# Tim Henigan
# Colin O'Flynn
# Reiner Patommel
# Markus Pfaff
# Sander Pool
# Frederik Rouleau
# Carlos Lamas
# Dean Camera
# Opendous Inc.
# Denver Gingerich
# Ruddick Lawrence
#
#----------------------------------------------------------------------------
# On command line:
#
# make all = Make software.
#
# make clean = Clean out built project files.
#
# make coff = Convert ELF to AVR COFF.
#
# make extcoff = Convert ELF to AVR Extended COFF.
#
# make program = Download the hex file to the device, using avrdude.
#                Please customize the avrdude settings below first!
#
# make dfu = Download the hex file to the device, using dfu-programmer (must
#            have dfu-programmer installed).
#
# make flip = Download the hex file to the device, using Atmel FLIP (must
#             have Atmel FLIP installed).
#
# make dfu-ee = Download the eeprom file to the device, using dfu-programmer
#               (must have dfu-programmer installed).
#
# make flip-ee = Download the eeprom file to the device, using Atmel FLIP
#                (must have Atmel FLIP installed).
#
# make doxygen = Generate DoxyGen documentation for the project (must have
#                DoxyGen installed)
#
# make debug = Start either simulavr or avarice as specified for debugging,
#              with avr-gdb or avr-insight as the front end for debugging.
#
# make filename.s = Just compile filename.c into the assembler code only.
#
# make filename.i = Create a preprocessed source file for use in submitting
#                   bug reports to the GCC project.
#
# To rebuild project do "make clean" then "make all".
#----------------------------------------------------------------------------


# MCU name
MCU = atmega32u4


# Target architecture (see library "Board Types" documentation).
ARCH = AVR8


# Target board (see library "Board Types" documentation, NONE for projects not requiring
# LUFA board drivers). If USER is selected, put custom board drivers in a directory called
# "Board" inside the application directory.
BOARD = NONE


# Processor frequency.
#     This will define a symbol, F_CPU, in all source code files equal to the
#     processor frequency in Hz. You can then use this symbol in your source code to
#     calculate timings. Do NOT tack on a 'UL' at the end, this will be done
#     automatically to create a 32-bit value in your source code.
#
#     This will be an integer division of F_USB below, as it is sourced by
#     F_USB after it has run through any CPU prescalers. Note that this value
#     does not *change* the processor frequency - it should merely be updated to
#     reflect the processor speed set externally so that the code can use accurate
#     software delays.
F_CPU = 16000000


# Input clock frequency.
#     This will define a symbol, F_USB, in all source code files equal to the
#     input clock frequency (before any prescaling is performed) in Hz. This value may
#     differ from F_CPU if prescaling is used on the latter, and is required as the
#     raw input clock is fed directly to the PLL sections of the AVR for high speed
#     clock generation for the USB and other AVR subsections. Do NOT tack on a 'UL'
#     at the end, this will be done automatically to create a 32-bit value in your
#     source code.
#
#     If no clock division is performed on the input clock inside the AVR (via the
#     CPU clock adjust registers or the clock division fuses), this will be equal to F_CPU.
F_USB = $(F_CPU)


# Output format. (can be srec, ihex, binary)
FORMAT = ihex


# Target file name (without extension).
TARGET = avr_chatter


# Object files directory
#     To put object files in current directory, use a dot (.), do NOT make
#     this an empty or blank macro!
OBJDIR = .

# Path to the LUFA library
LUFA_PATH = .


# LUFA library compile-time options and predefined tokens
LUFA_OPTS  = -D USB_DEVICE_ONLY
LUFA_OPTS += -D FIXED_CONTROL_ENDPOINT_SIZE=8
LUFA_OPTS += -D FIXED_NUM_CONFIGURATIONS=1
LUFA_OPTS += -D USE_FLASH_DESCRIPTORS
LUFA_OPTS += -D USE_STATIC_OPTIONS="(USB_DEVICE_OPT_FULLSPEED | USB_OPT_REG_ENABLED | USB_OPT_AUTO_PLL)"


# Create the LUFA source path variables by including the LUFA root makefile
include $(LUFA_PATH)/LUFA/makefile


# List C source files here. (C dependencies are automatically generated.)
SRC = avr_time.c Descriptors.c $(LUFA_SRC_USB) $(LUFA_SRC_USBCLASS)


# List C++ source files here. (C dependencies are automatically generated.)
CPPSRC = $(TARGET).cpp Atmega32u4Hardware.cpp ros_lib/time.cpp ros_lib/duration.cpp


# List Assembler source files here.
#     Make them always end in a capital .S.  Files ending in a lowercase .s
#     will not be considered source files but generated files (assembler
#     output from the compiler), and will be deleted upon "make clean"!
#     Even though the DOS/Win* filesystem matches both .s and .S the same,
#     it will preserve the spelling of the filenames, and gcc itself does
#     care about how the name is spelled on its command-line.
ASRC =


# Optimization level, can be [0, 1, 2, 3, s].
#     0 = turn off optimization. s = optimize for size.
#     (Note: 3 is not always the best optimization level. See avr-libc FAQ.)
OPT = s


# Debugging format.
#     Native formats for AVR-GCC's -g are dwarf-2 [default] or stabs.
#     AVR Studio 4.10 requires dwarf-2.
#     AVR [Extended] COFF format requires stabs, plus an avr-objcopy run.
DEBUG = dwarf-2


# List any extra directories to look for include files here.
#     Each directory must be seperated by a space.
#     Use forward slashes for directory separators.
#     For a directory that has spaces, enclose it in quotes.
EXTRAINCDIRS = $(LUFA_PATH)/ ./ros_lib/


# Compiler flag to set the C Standard level.
#     c89   = "ANSI" C
#     gnu89 = c89 plus GCC extensions
#     c99   = ISO C99 standard (not yet fully implemented)
#     gnu99 = c99 plus GCC extensions
CSTANDARD = -std=c99


# Place -D or -U options here for C sources
CDEFS  = -DF_CPU=$(F_CPU)UL
CDEFS += -DF_USB=$(F_USB)UL
CDEFS += -DBOARD=BOARD_$(BOARD) -DARCH=ARCH_$(ARCH)
CDEFS += $(LUFA_OPTS)


# Place -D or -U options here for ASM sources
ADEFS  = -DF_CPU=$(F_CPU)
ADEFS += -DF_USB=$(F_USB)UL
ADEFS += -DBOARD=BOARD_$(BOARD) -DARCH=ARCH_$(ARCH)
ADEFS += $(LUFA_OPTS)

# Place -D or -U options here for C++ sources
CPPDEFS  = -DF_CPU=$(F_CPU)UL
CPPDEFS += -DF_USB=$(F_USB)UL
CPPDEFS += -DBOARD=BOARD_$(BOARD) -DARCH=ARCH_$(ARCH)
CPPDEFS += $(LUFA_OPTS)
#CPPDEFS += -D__STDC_LIMIT_MACROS
#CPPDEFS += -D__STDC_CONSTANT_MACROS



#---------------- Compiler Options C ----------------
#  -g*:          generate debugging information
#  -O*:          optimization level
#  -f...:        tuning, see GCC manual and avr-libc documentation
#  -Wall...:     warning level
#  -Wa,...:      tell GCC to pass this to the assembler.
#    -adhlns...: create assembler listing
CFLAGS = -g$(DEBUG)
CFLAGS += $(CDEFS)
CFLAGS += -O$(OPT)
CFLAGS += -funsigned-char
CFLAGS += -funsigned-bitfields
CFLAGS += -ffunction-sections
CFLAGS += -fno-inline-small-functions
CFLAGS += -fpack-struct
CFLAGS += -fshort-enums
CFLAGS += -fno-strict-aliasing
CFLAGS += -Wall
CFLAGS += -Wstrict-prototypes
#CFLAGS += -mshort-calls
#CFLAGS += -fno-unit-at-a-time
#CFLAGS += -Wundef
#CFLAGS += -Wunreachable-code
#CFLAGS += -Wsign-compare
CFLAGS += -Wa,-adhlns=$(<:%.c=$(OBJDIR)/%.lst)
CFLAGS += $(patsubst %,-I%,$(EXTRAINCDIRS))
CFLAGS += $(CSTANDARD)


#---------------- Compiler Options C++ ----------------
#  -g*:          generate debugging information
#  -O*:          optimization level
#  -f...:        tuning, see GCC manual and avr-libc documentation
#  -Wall...:     warning level
#  -Wa,...:      tell GCC to pass this to the assembler.
#    -adhlns...: create assembler listing
CPPFLAGS = -g$(DEBUG)
CPPFLAGS += $(CPPDEFS)
CPPFLAGS += -O$(OPT)
CPPFLAGS += -funsigned-char
CPPFLAGS += -funsigned-bitfields
CPPFLAGS += -fpack-struct
CPPFLAGS += -fshort-enums
CPPFLAGS += -fno-exceptions
CPPFLAGS += -Wall
CPPFLAGS += -Wundef
#CPPFLAGS += -mshort-calls
#CPPFLAGS += -fno-unit-at-a-time
#CPPFLAGS += -Wstrict-prototypes
#CPPFLAGS += -Wunreachable-code
#CPPFLAGS += -Wsign-compare
CPPFLAGS += -Wa,-adhlns=$(<:%.cpp=$(OBJDIR)/%.lst)
CPPFLAGS += $(patsubst %,-I%,$(EXTRAINCDIRS))
#CPPFLAGS += $(CSTANDARD)


#---------------- Assembler Options ----------------
#  -Wa,...:   tell GCC to pass this to the assembler.
#  -adhlns:   create listing
#  -gstabs:   have the assembler create line number information; note that
#             for use in COFF files, additional information about filenames
#             and function names needs to be present in the assembler source
#             files -- see avr-libc docs [FIXME: not yet described there]
#  -listing-cont-lines: Sets the maximum number of continuation lines of hex
#       dump that will be displayed for a given single line of source input.
ASFLAGS = $(ADEFS) -Wa,-adhlns=$(<:%.S=$(OBJDIR)/%.lst),-gstabs,--listing-cont-lines=100


#---------------- Library Options ----------------
# Minimalistic printf version
PRINTF_LIB_MIN = -Wl,-u,vfprintf -lprintf_min

# Floating point printf version (requires MATH_LIB = -lm below)
PRINTF_LIB_FLOAT = -Wl,-u,vfprintf -lprintf_flt

# If this is left blank, then it will use the Standard printf version.
PRINTF_LIB =
#PRINTF_LIB = $(PRINTF_LIB_MIN)
#PRINTF_LIB = $(PRINTF_LIB_FLOAT)


# Minimalistic scanf version
SCANF_LIB_MIN = -Wl,-u,vfscanf -lscanf_min

# Floating point + %[ scanf version (requires MATH_LIB = -lm below)
SCANF_LIB_FLOAT = -Wl,-u,vfscanf -lscanf_flt

# If this is left blank, then it will use the Standard scanf version.
SCANF_LIB =
#SCANF_LIB = $(SCANF_LIB_MIN)
#SCANF_LIB = $(SCANF_LIB_FLOAT)


MATH_LIB = -lm


# List any extra directories to look for libraries here.
#     Each directory must be seperated by a space.
#     Use forward slashes for directory separators.
#     For a directory that has spaces, enclose it in quotes.
EXTRALIBDIRS =



#---------------- External Memory Options ----------------

# 64 KB of external RAM, starting after internal RAM (ATmega128!),
# used for variables (.data/.bss) and heap (malloc()).
#EXTMEMOPTS = -Wl,-Tdata=0x801100,--defsym=__heap_end=0x80ffff

# 64 KB of external RAM, starting after internal RAM (ATmega128!),
# only used for heap (malloc()).
#EXTMEMOPTS = -Wl,--section-start,.data=0x801100,--defsym=__heap_end=0x80ffff

EXTMEMOPTS =



#---------------- Linker Options ----------------
#  -Wl,...:     tell GCC to pass this to linker.
#    -Map:      create map file
#    --cref:    add cross reference to  map file
LDFLAGS  = -Wl,-Map=$(TARGET).map,--cref
LDFLAGS += -Wl,--relax
LDFLAGS += -Wl,--gc-sections
LDFLAGS += $(EXTMEMOPTS)
LDFLAGS += $(patsubst %,-L%,$(EXTRALIBDIRS))
LDFLAGS += $(PRINTF_LIB) $(SCANF_LIB) $(MATH_LIB)
#LDFLAGS += -T linker_script.x



#---------------- Programming Options (avrdude) ----------------

# Programming hardware
# Type: avrdude -c ?
# to get a full listing.
#
AVRDUDE_PROGRAMMER = avr109

# com1 = serial port. Use lpt1 to connect to parallel port.
AVRDUDE_PORT = /dev/ttyACM0

AVRDUDE_WRITE_FLASH = -U flash:w:$(TARGET).hex
#AVRDUDE_WRITE_EEPROM = -U eeprom:w:$(TARGET).eep


# Uncomment the following if you want avrdude's erase cycle counter.
# Note that this counter needs to be initialized first using -Yn,
# see avrdude manual.
#AVRDUDE_ERASE_COUNTER = -y

# Uncomment the following if you do /not/ wish a verification to be
# performed after programming the device.
#AVRDUDE_NO_VERIFY = -V

# Increase verbosity level.  Please use this when submitting bug
# reports about avrdude. See <http://savannah.nongnu.org/projects/avrdude>
# to submit bug reports.
#AVRDUDE_VERBOSE = -v -v

AVRDUDE_FLAGS = -p $(MCU) -P $(AVRDUDE_PORT) -c $(AVRDUDE_PROGRAMMER)
AVRDUDE_FLAGS += $(AVRDUDE_NO_VERIFY)
AVRDUDE_FLAGS += $(AVRDUDE_VERBOSE)
AVRDUDE_FLAGS += $(AVRDUDE_ERASE_COUNTER)



#---------------- Debugging Options ----------------

# For simulavr only - target MCU frequency.
DEBUG_MFREQ = $(F_CPU)

# Set the DEBUG_UI to either gdb or insight.
# DEBUG_UI = gdb
DEBUG_UI = insight

# Set the debugging back-end to either avarice, simulavr.
DEBUG_BACKEND = avarice
#DEBUG_BACKEND = simulavr

# GDB Init Filename.
GDBINIT_FILE = __avr_gdbinit

# When using avarice settings for the JTAG
JTAG_DEV = /dev/com1

# Debugging port used to communicate between GDB / avarice / simulavr.
DEBUG_PORT = 4242

# Debugging host used to communicate between GDB / avarice / simulavr, normally
#     just set to localhost unless doing some sort of crazy debugging when
#     avarice is running on a different computer.
DEBUG_HOST = localhost



#============================================================================


# Define programs and commands.
SHELL = sh
CC = avr-gcc
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
SIZE = avr-size
AR = avr-ar rcs
NM = avr-nm
AVRDUDE = avrdude
REMOVE = rm -f
REMOVEDIR = rm -rf
COPY = cp
WINSHELL = cmd


# Define Messages
# English
MSG_ERRORS_NONE = Errors: none
MSG_BEGIN = -------- begin --------
MSG_END = --------  end  --------
MSG_SIZE_BEFORE = Size before:
MSG_SIZE_AFTER = Size after:
MSG_COFF = Converting to AVR COFF:
MSG_EXTENDED_COFF = Converting to AVR Extended COFF:
MSG_FLASH = Creating load file for Flash:
MSG_EEPROM = Creating load file for EEPROM:
MSG_EXTENDED_LISTING = Creating Extended Listing:
MSG_SYMBOL_TABLE = Creating Symbol Table:
MSG_LINKING = Linking:
MSG_COMPILING = Compiling C:
MSG_COMPILING_CPP = Compiling C++:
MSG_ASSEMBLING = Assembling:
MSG_CLEANING = Cleaning project:
MSG_CREATING_LIBRARY = Creating library:




# Define all object files.
OBJ = $(SRC:%.c=$(OBJDIR)/%.o) $(CPPSRC:%.cpp=$(OBJDIR)/%.o) $(ASRC:%.S=$(OBJDIR)/%.o)

# Define all listing files.
LST = $(SRC:%.c=$(OBJDIR)/%.lst) $(CPPSRC:%.cpp=$(OBJDIR)/%.lst) $(ASRC:%.S=$(OBJDIR)/%.lst)


# Compiler flags to generate dependency files.
GENDEPFLAGS = -MMD -MP -MF .dep/$(@F).d


# Combine all necessary flags and optional flags.
# Add target processor to flags.
ALL_CFLAGS = -mmcu=$(MCU) -I. $(CFLAGS) $(GENDEPFLAGS)
ALL_CPPFLAGS = -mmcu=$(MCU) -I. -x c++ $(CPPFLAGS) $(GENDEPFLAGS)
ALL_ASFLAGS = -mmcu=$(MCU) -I. -x assembler-with-cpp $(ASFLAGS)





# Default target.
all: begin gccversion sizebefore build sizeafter end

# Change the build target to build a HEX file or a library.
build: elf hex eep lss sym
#build: lib


elf: $(TARGET).elf
hex: $(TARGET).hex
eep: $(TARGET).eep
lss: $(TARGET).lss
sym: $(TARGET).sym
LIBNAME=lib$(TARGET).a
lib: $(LIBNAME)



# Eye candy.
# AVR Studio 3.x does not check make's exit code but relies on
# the following magic strings to be generated by the compile job.
begin:
        @echo
        @echo $(MSG_BEGIN)

end:
        @echo $(MSG_END)
        @echo


# Display size of file.
HEXSIZE = $(SIZE) --target=$(FORMAT) $(TARGET).hex
ELFSIZE = $(SIZE) $(MCU_FLAG) $(FORMAT_FLAG) $(TARGET).elf
MCU_FLAG = $(shell $(SIZE) --help | grep -- --mcu > /dev/null && echo --mcu=$(MCU) )
FORMAT_FLAG = $(shell $(SIZE) --help | grep -- --format=.*avr > /dev/null && echo --format=avr )


sizebefore:
        @if test -f $(TARGET).elf; then echo; echo $(MSG_SIZE_BEFORE); $(ELFSIZE); \
        2>/dev/null; echo; fi

sizeafter:
        @if test -f $(TARGET).elf; then echo; echo $(MSG_SIZE_AFTER); $(ELFSIZE); \
        2>/dev/null; echo; fi



# Display compiler version information.
gccversion :
        @$(CC) --version


# Program the device.
program: $(TARGET).hex $(TARGET).eep
        $(AVRDUDE) $(AVRDUDE_FLAGS) $(AVRDUDE_WRITE_FLASH) $(AVRDUDE_WRITE_EEPROM)

flip: $(TARGET).hex
        batchisp -hardware usb -device $(MCU) -operation erase f
        batchisp -hardware usb -device $(MCU) -operation loadbuffer $(TARGET).hex program
        batchisp -hardware usb -device $(MCU) -operation start reset 0

dfu: $(TARGET).hex
        dfu-programmer $(MCU) erase
        dfu-programmer $(MCU) flash $(TARGET).hex
        dfu-programmer $(MCU) reset

flip-ee: $(TARGET).hex $(TARGET).eep
        $(COPY) $(TARGET).eep $(TARGET)eep.hex
        batchisp -hardware usb -device $(MCU) -operation memory EEPROM erase
        batchisp -hardware usb -device $(MCU) -operation memory EEPROM loadbuffer $(TARGET)eep.hex program
        batchisp -hardware usb -device $(MCU) -operation start reset 0
        $(REMOVE) $(TARGET)eep.hex

dfu-ee: $(TARGET).hex $(TARGET).eep
        dfu-programmer $(MCU) eeprom-flash $(TARGET).eep
        dfu-programmer $(MCU) reset


# Generate avr-gdb config/init file which does the following:
#     define the reset signal, load the target file, connect to target, and set
#     a breakpoint at main().
gdb-config:
        @$(REMOVE) $(GDBINIT_FILE)
        @echo define reset >> $(GDBINIT_FILE)
        @echo SIGNAL SIGHUP >> $(GDBINIT_FILE)
        @echo end >> $(GDBINIT_FILE)
        @echo file $(TARGET).elf >> $(GDBINIT_FILE)
        @echo target remote $(DEBUG_HOST):$(DEBUG_PORT)  >> $(GDBINIT_FILE)
ifeq ($(DEBUG_BACKEND),simulavr)
        @echo load  >> $(GDBINIT_FILE)
endif
        @echo break main >> $(GDBINIT_FILE)

debug: gdb-config $(TARGET).elf
ifeq ($(DEBUG_BACKEND), avarice)
        @echo Starting AVaRICE - Press enter when "waiting to connect" message displays.
        @$(WINSHELL) /c start avarice --jtag $(JTAG_DEV) --erase --program --file \
        $(TARGET).elf $(DEBUG_HOST):$(DEBUG_PORT)
        @$(WINSHELL) /c pause

else
        @$(WINSHELL) /c start simulavr --gdbserver --device $(MCU) --clock-freq \
        $(DEBUG_MFREQ) --port $(DEBUG_PORT)
endif
        @$(WINSHELL) /c start avr-$(DEBUG_UI) --command=$(GDBINIT_FILE)




# Convert ELF to COFF for use in debugging / simulating in AVR Studio or VMLAB.
COFFCONVERT = $(OBJCOPY) --debugging
COFFCONVERT += --change-section-address .data-0x800000
COFFCONVERT += --change-section-address .bss-0x800000
COFFCONVERT += --change-section-address .noinit-0x800000
COFFCONVERT += --change-section-address .eeprom-0x810000



coff: $(TARGET).elf
        @echo
        @echo $(MSG_COFF) $(TARGET).cof
        $(COFFCONVERT) -O coff-avr $< $(TARGET).cof


extcoff: $(TARGET).elf
        @echo
        @echo $(MSG_EXTENDED_COFF) $(TARGET).cof
        $(COFFCONVERT) -O coff-ext-avr $< $(TARGET).cof



# Create final output files (.hex, .eep) from ELF output file.
%.hex: %.elf
        @echo
        @echo $(MSG_FLASH) $@
        $(OBJCOPY) -O $(FORMAT) -R .eeprom -R .fuse -R .lock $< $@

%.eep: %.elf
        @echo
        @echo $(MSG_EEPROM) $@
        -$(OBJCOPY) -j .eeprom --set-section-flags=.eeprom="alloc,load" \
        --change-section-lma .eeprom=0 --no-change-warnings -O $(FORMAT) $< $@ || exit 0

# Create extended listing file from ELF output file.
%.lss: %.elf
        @echo
        @echo $(MSG_EXTENDED_LISTING) $@
        $(OBJDUMP) -h -S -z $< > $@

# Create a symbol table from ELF output file.
%.sym: %.elf
        @echo
        @echo $(MSG_SYMBOL_TABLE) $@
        $(NM) -n $< > $@



# Create library from object files.
.SECONDARY : $(TARGET).a
.PRECIOUS : $(OBJ)
%.a: $(OBJ)
        @echo
        @echo $(MSG_CREATING_LIBRARY) $@
        $(AR) $@ $(OBJ)


# Link: create ELF output file from object files.
.SECONDARY : $(TARGET).elf
.PRECIOUS : $(OBJ)
%.elf: $(OBJ)
        @echo
        @echo $(MSG_LINKING) $@
        $(CC) $(ALL_CFLAGS) $^ --output $@ $(LDFLAGS)


# Compile: create object files from C source files.
$(OBJDIR)/%.o : %.c
        @echo
        @echo $(MSG_COMPILING) $<
        $(CC) -c $(ALL_CFLAGS) $< -o $@


# Compile: create object files from C++ source files.
$(OBJDIR)/%.o : %.cpp
        @echo
        @echo $(MSG_COMPILING_CPP) $<
        $(CC) -c $(ALL_CPPFLAGS) $< -o $@


# Compile: create assembler files from C source files.
%.s : %.c
        $(CC) -S $(ALL_CFLAGS) $< -o $@


# Compile: create assembler files from C++ source files.
%.s : %.cpp
        $(CC) -S $(ALL_CPPFLAGS) $< -o $@


# Assemble: create object files from assembler source files.
$(OBJDIR)/%.o : %.S
        @echo
        @echo $(MSG_ASSEMBLING) $<
        $(CC) -c $(ALL_ASFLAGS) $< -o $@


# Create preprocessed source for use in sending a bug report.
%.i : %.c
        $(CC) -E -mmcu=$(MCU) -I. $(CFLAGS) $< -o $@


# Target: clean project.
clean: begin clean_list end

clean_list :
        @echo
        @echo $(MSG_CLEANING)
        $(REMOVE) $(TARGET).hex
        $(REMOVE) $(TARGET).eep
        $(REMOVE) $(TARGET).cof
        $(REMOVE) $(TARGET).elf
        $(REMOVE) $(TARGET).map
        $(REMOVE) $(TARGET).sym
        $(REMOVE) $(TARGET).lss
        $(REMOVE) $(SRC:%.c=$(OBJDIR)/%.o) $(CPPSRC:%.cpp=$(OBJDIR)/%.o) $(ASRC:%.S=$(OBJDIR)/%.o)
        $(REMOVE) $(SRC:%.c=$(OBJDIR)/%.lst) $(CPPSRC:%.cpp=$(OBJDIR)/%.lst) $(ASRC:%.S=$(OBJDIR)/%.lst)
        $(REMOVE) $(SRC:.c=.s)
        $(REMOVE) $(SRC:.c=.d)
        $(REMOVE) $(SRC:.c=.i)
        $(REMOVEDIR) .dep

doxygen:
        @echo Generating Project Documentation \($(TARGET)\)...
        @doxygen Doxygen.conf
        @echo Documentation Generation Complete.

clean_doxygen:
        rm -rf Documentation

checksource:
        @for f in $(SRC) $(CPPSRC) $(ASRC); do \
                if [ -f $$f ]; then \
                        echo "Found Source File: $$f" ; \
                else \
                        echo "Source File Not Found: $$f" ; \
                fi; done 


# Create object files directory
$(shell mkdir $(OBJDIR) 2>/dev/null)


# Include the dependency files.
-include $(shell mkdir .dep 2>/dev/null) $(wildcard .dep/*)


# Listing of phony targets.
.PHONY : all begin finish end sizebefore sizeafter gccversion \
build elf hex eep lss sym coff extcoff doxygen clean          \
clean_list clean_doxygen program dfu flip flip-ee dfu-ee      \
debug gdb-config checksource

Let's look some of the new variables you might need to understand:

# Target architecture (see library "Board Types" documentation).
ARCH = AVR8

The AVR architecture (we are using an 8-bit AVR).

# Target board (see library "Board Types" documentation, NONE for projects not requiring
# LUFA board drivers). If USER is selected, put custom board drivers in a directory called
# "Board" inside the application directory.
BOARD = NONE

LUFA has some drivers (button, LED, etc) that use this variable to determine which breakout board is being used. Since our code doesn't use any of those drivers, leave it set to NONE.

# Input clock frequency.
#     This will define a symbol, F_USB, in all source code files equal to the
#     input clock frequency (before any prescaling is performed) in Hz. This value may
#     differ from F_CPU if prescaling is used on the latter, and is required as the
#     raw input clock is fed directly to the PLL sections of the AVR for high speed
#     clock generation for the USB and other AVR subsections. Do NOT tack on a 'UL'
#     at the end, this will be done automatically to create a 32-bit value in your
#     source code.
#
#     If no clock division is performed on the input clock inside the AVR (via the
#     CPU clock adjust registers or the clock division fuses), this will be equal to F_CPU.
F_USB = $(F_CPU)

The frequency of the clock used by LUFA for USB communications. Change this if it is different than the microcontroller processor speed.

# Path to the LUFA library
LUFA_PATH = .

The path to the directory that contains the LUFA library.

For any other options you may need to change, please see the previous tutorial's Makefile section

Building

To build the firmware, go into your package directory and run:

make
make program

Testing

To test the code, plug the Atmega32u4 into the PC's USB port. In a terminal window launch roscore:

roscore

Next, start the rosserial client (replace /dev/ttyACM0 with the USB port your AVR is connected to):

rosrun rosserial_python serial_node.py /dev/ttyACM0

And watch the incoming messages:

rostopic echo chatter

Wiki: rosserial_client/Tutorials/Using rosserial with AVR and USB (last edited 2012-02-14 07:01:57 by RuddickLawrence)