Note: This tutorial assumes you are familiar with the previous tutorials Adding Support for New Hardware, Adding Support for New Hardware, and Hello World (example publisher).

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 UART

Description: This tutorial will show you how to get the rosserial_arduino Hello World (example publisher) tutorial running on an AVR.

Keywords: rosserial, rosserial_client, AVR, embedded, microcontroller

Tutorial Level: INTERMEDIATE

Next Tutorial: The next tutorial will show you how to use rosserial_client with USB Using rosserial with AVR and USB

Contents

Source Code
Prerequisites
1. AVR Development Environment
2. Hardware
Setting Up the ROS Package
New Modules
1. avr_time
2. avr_uart
Implementing rosserial_client
Makefile
Building the AVR Program
Running the Code

Source Code

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

Prerequisites

AVR Development Environment

You will first have to set up your AVR development environment. This tutorial will assume you have the following tools installed:

avr-binutils: The low-level utilities to build and manipulate object files.
avr-libc: The C runtime library for the AVR family of microcontrollers.
avr-gcc: The gcc compiler for AVR.
avrdude: A utility to program the Flash and EEPROM of AVRs.

Ubuntu has packages for each utility, but be warned that they lag behind the latest stable versions, and therefore do not always support the latest microcontrollers. To install the packages, run:

sudo apt-get install binutils-avr avr-libc gcc-avr avrdude

You can install avr-binutils, avr-libc, and avr-gcc from source from http://savannah.nongnu.org/projects/avr-libc, and avrdude from http://savannah.nongnu.org/projects/avrdude.

Hardware

This tutorial is written for the Atmega32u4, but you can fairly easily substitute other AVR chips by modifying the Makefile and the data registers in the avr_time and avr_uart modules below.

We will use the Atmega32u4's UART to communicate with the PC's serial port. To do this, the signal must go through a simple level shifter:

Setting Up the ROS Package

Create a new ROS package and set up the directory structure we will use:

roscreate-pkg rosserial_avr_tutorial
cd rosserial_avr_tutorial && mkdir -p src/ros_lib/ros

We will also need to copy over a number of source files from the rosserial_arduino package:

roscd rosserial_arduino/libraries/ros_lib
cp -R duration.cpp time.cpp `(rospack find rosserial_avr_tutorial)`/src/ros_lib/

New Modules

The rosserial_client interface requires that you implement a function that returns the milliseconds since the start of the program, and the communications send/receive functions. We will do that by writing two modules: avr_time and avr_uart.

avr_time

The avr_time module uses an interrupt to count the number of timer overflows since the program started running, and converts it into milliseconds.

avr_time.h

   1 #ifndef _AVR_TIME_H_
   2 #define _AVR_TIME_H_
   3 
   4 #include <stdint.h>
   5 
   6 void avr_time_init(void);
   7 uint32_t avr_time_now(void);
   8 
   9 #endif
  10

avr_time.c

   1 #include "avr_time.h"
   2 #include <avr/io.h>
   3 #include <avr/interrupt.h>
   4 
   5 #define CLOCK_TICKS_PER_MS F_CPU / 1000UL
   6 // Timer0 is 8 bits and is prescaled by 64
   7 #define CLOCK_TICKS_PER_TIMER0_OVERFLOW 64UL * 256UL
   8 
   9 volatile static uint32_t timer0_ticks = 0;
  10 volatile static uint32_t overflow_ms = 0;
  11 
  12 // The Timer0 overflow interrupt handler
  13 ISR(TIMER0_OVF_vect)
  14 {
  15   // Add an overflow's worth of time
  16   timer0_ticks += CLOCK_TICKS_PER_TIMER0_OVERFLOW;
  17   for(; timer0_ticks > CLOCK_TICKS_PER_MS; timer0_ticks -= CLOCK_TICKS_PER_MS)
  18   {
  19     overflow_ms++;
  20   }
  21 }
  22 
  23 // Initialize the 8-bit Timer 0.
  24 void avr_time_init(void)
  25 {
  26   // Prescale Timer 0 to divide by 64
  27   TCCR0B |= _BV(CS01) | _BV(CS00);
  28   // Enable Timer 0 overflow interrupt
  29   TIMSK0 |= _BV(TOIE0);
  30 }
  31 
  32 // Get the current time in milliseconds
  33 uint32_t avr_time_now(void)
  34 {
  35   uint32_t now;
  36 
  37   // Disable interrupts
  38   cli();
  39   now = overflow_ms;
  40   sei();
  41 
  42   return now;
  43 }

avr_uart

The avr_uart module sets up the AVR's UART and can send and receive data.

avr_uart.h

#ifndef _AVR_UART_H_
#define _AVR_UART_H_

void avr_uart_init(void);
void avr_uart_send_byte(uint8_t tx_byte);
int16_t avr_uart_receive_byte(void);

#endif

avr_uart.c

#include <avr/io.h>

#define BAUD 57600
#define UBRR_VAL ((F_CPU / (16UL * BAUD)) - 1)


// Initialize the UART
void avr_uart_init(void)
{
  // Enable bidirectional UART
  UCSR1B |= _BV(RXEN1) | _BV(TXEN1);
  // Use 8-bit characters
  UCSR1C |= _BV(UCSZ10) | _BV(UCSZ11);
  // Set the Baud rate
  UBRR1H = (UBRR_VAL >> 8);
  UBRR1L = UBRR_VAL;
}


// Send one char (blocking)
void avr_uart_send_byte(uint8_t tx_byte)
{
  // Wait to be able to transmit
  while((UCSR1A & _BV(UDRE1)) == 0)
    asm volatile("nop"::);
  // Put the data into the send buffer
  UDR1 = tx_byte;
}


// Get one char if available, otherwise -1
int16_t avr_uart_receive_byte(void)
{
  if((UCSR1A & _BV(RXC1)) != 0)
  {
    return UDR1;
  }
  else
  {
    return -1;
  }
}

Implementing rosserial_client

Defining the Hardware Interface

To use rosserial with our AVR, we have to define a new hardware header as outlined in the Adding Support for New Hardware tutorial:

Atmega32u4Hardware.h

#ifndef _ATMEGA32U4_HARDWARE_H
#define _ATMEGA32U4_HARDWARE_H

extern "C"
{
  #include <avr/interrupt.h>
  #include <avr/wdt.h>
  #include "avr_time.h"
  #include "avr_uart.h"
}

class Atmega32u4Hardware {
  public:
    Atmega32u4Hardware() {}


    // Initialize the AVR
    void init()
    {
      wdt_disable();
      avr_time_init();
      avr_uart_init();
      sei();
    }

    // Read a byte of data from ROS connection.
    // If no data, returns -1
    int read()
    {
      return avr_uart_receive_byte();
    }


    // Send a byte of data to ROS connection
    void write(uint8_t* data, int length)
    {
      for(int i = 0; i < length; i++)
      {
        avr_uart_send_byte(data[i]);
      }
    }


    // Returns milliseconds since start of program
    unsigned long time()
    {
      return avr_time_now();
    }
  };

#endif

We will also create a typedef for convenience:

ros.h

#ifndef _ROS_H_
#define _ROS_H_

#include "ros/node_handle.h"
#include "Atmega32u4Hardware.h"

namespace ros
{
  typedef ros::NodeHandle_<Atmega32u4Hardware> NodeHandle;
}

#endif

Writing a rosserial Chatter Node

The chatter program we are writing is an adaptation of the rosserial_arduino Hello World (example publisher) tutorial:

avr_chatter.cpp

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

  return 0;
}

Generating the ROS Message Headers

We have to generate message headers for std_msgs and rosserial_msgs (see Generating Message Header Files). Open a terminal, and in the rosserial_avr_tutorial/src directory run:

rosrun rosserial_client make_library.py . std_msgs
rosrun rosserial_client make_library.py . rosserial_msgs

Makefile

We are going to use a Makefile to build the firmware and program the Atmega32u4 (this means it will not be part of the rosbuild system). The following Makefile was adapted from the WinAVR Makefile template:

# Hey Emacs, this is a -*- makefile -*-
#----------------------------------------------------------------------------
# WinAVR Makefile Template written by Eric B. Weddington, Jörg Wunsch, et al.
#  >> Modified for the 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
# 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 debug = Start either simulavr or avarice as specified foebugging,
#              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


# Processor frequency.
#     This will define a symbol, F_CPU, in all source code files equal to the
#     processor frequency. 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.
#     Typical values are:
#         F_CPU =  1000000
#         F_CPU =  1843200
#         F_CPU =  2000000
#         F_CPU =  3686400
#         F_CPU =  4000000
#         F_CPU =  7372800
#         F_CPU =  8000000
#         F_CPU = 11059200
#         F_CPU = 14745600
#         F_CPU = 16000000
#         F_CPU = 18432000
#         F_CPU = 20000000
F_CPU = 16000000


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


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


# Object files directory
OBJDIR = .


# List C source files here. (C dependencies are automatically generated.)
SRC = avr_time.c avr_uart.c


# List C++ source files here. (C dependencies are automatically generated.)
CPPSRC = $(TARGET).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 = ./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=gnu99


# Place -D or -U options here for C sources
CDEFS = -DF_CPU=$(F_CPU)UL


# Place -D or -U options here for C++ sources
CPPDEFS = -DF_CPU=$(F_CPU)UL
#CPPDEFS += -D__STDC_LIMIT_MACROS
#CPPDEFS += -D__STDC_CONSTANT_MACROS


# Place -I options here for C sources
CINCS =


# Place -I options here for C++ sources
CPPINCS =


#---------------- 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 += $(CINCS)
CFLAGS += -O$(OPT)
#CFLAGS += -mint8
#CFLAGS += -mshort-calls
CFLAGS += -funsigned-char
CFLAGS += -funsigned-bitfields
CFLAGS += -fpack-struct
CFLAGS += -fshort-enums
#CFLAGS += -fno-unit-at-a-time
CFLAGS += -Wall
CFLAGS += -Wstrict-prototypes
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 += $(CPPINCS)
CPPFLAGS += -O$(OPT)
#CPPFLAGS += -mint8
#CPPFLAGS += -mshort-calls
CPPFLAGS += -funsigned-char
CPPFLAGS += -funsigned-bitfields
CPPFLAGS += -fpack-struct
CPPFLAGS += -fshort-enums
CPPFLAGS += -fno-exceptions
#CPPFLAGS += -fno-unit-at-a-time
CPPFLAGS += -Wall
#CPPFLAGS += -Wstrict-prototypes
CFLAGS += -Wundef
#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.
#  -ahlms:    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]
ASFLAGS = -Wa,-adhlns=$(<:%.S=$(OBJDIR)/%.lst),-gstabs


#---------------- 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



#---------------- 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,--defsym=__heap_start=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 += $(EXTMEMOPTS)
LDFLAGS += $(PRINTF_LIB) $(SCANF_LIB) $(MATH_LIB)
#LDFLAGS += -T linker_script.x



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

# Programming hardware: alf avr910 avrisp bascom bsd
# dt006 pavr picoweb pony-stk200 sp12 stk200 stk500
#
# Type: avrdude -c ?
# to get a full listing.
#
AVRDUDE_PROGRAMMER = avr109

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
NM = avr-nm
AVRDUDE = avrdude
REMOVE = rm -f
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:




# 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 = -MD -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

build: elf hex eep lss sym

elf: $(TARGET).elf
hex: $(TARGET).hex
eep: $(TARGET).eep
lss: $(TARGET).lss
sym: $(TARGET).sym



# 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) -A $(TARGET).elf
AVRMEM = avr-mem.sh $(TARGET).elf $(MCU)

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

sizeafter:
        @if test -f $(TARGET).elf; then echo; echo $(MSG_SIZE_AFTER); $(ELFSIZE); \
        $(AVRMEM) 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)


# 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 $< $@

%.eep: %.elf
        @echo
        @echo $(MSG_EEPROM) $@
        -$(OBJCOPY) -j .eeprom --set-section-flags=.eeprom="alloc,load" \
        --change-section-lma .eeprom=0 -O $(FORMAT) $< $@

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

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



# 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)
        $(REMOVE) .dep/*


# 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 \
clean clean_list program debug gdb-config

The Makefile contains a lot of code to make sure the program compiles correctly, but you only need to worry about a portion of it.

Error: No code_block found

Specifies which microcontroller you are using. You can find the the other AVR options here: http://www.nongnu.org/avr-libc/user-manual/using_tools.html

Error: No code_block found

The clock speed of your microcontroller (here it is 16MHz). Be sure to change this if you are running at a different speed.

Error: No code_block found

This is the name of the program you are compiling.

Error: No code_block found

These are the source files used in your program. $(TARGET).cpp selects the C++ file specified by TARGET above (avr_chatter.cpp in this case).

Error: No code_block found

These are any other directories (besides the main project directories) that contain include (.h) files your program needs.

Error: No code_block found

The avrdude variables specify how to program the hex file onto the microcontroller. AVRDUDE_PROGRAMMER is the device you're using to program the AVR, and AVRDUDE_PORT is which port that programmer is attached to. In this example, avrdude is programming the Atmega32u4 over USB using a preinstalled bootloader.

Building the AVR Program

Now that everything is set up, your package directory should look like this (rosserial_msgs and std_msgs contain too many message header files to show):

Open a terminal, change directories to rosserial_avr_tutorial/src and run:

make

If the firmware builds successfully, it should have created the file rosserial_avr_tutorial/src/avr_chatter.hex. Now you need to load it onto your Atmega32u4. Attach the AVR to your programmer and power it up. From your project directory run:

make program

If it programmed successfully, you should see output similar to this:

avrdude -p atmega32u4 -P /dev/ttyACM0     -c avr109    -U flash:w:avr_chatter.hex

Connecting to programmer: .
Found programmer: Id = "LUFACDC"; type = S
    Software Version = 1.0; No Hardware Version given.
Programmer supports auto addr increment.
Programmer supports buffered memory access with buffersize=128 bytes.

Programmer supports the following devices:
    Device code: 0x44

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e9587
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "avr_chatter.hex"
avrdude: input file avr_chatter.hex auto detected as Intel Hex
avrdude: writing flash (9336 bytes):

Writing | ################################################## | 100% 0.81s



avrdude: 9336 bytes of flash written
avrdude: verifying flash memory against avr_chatter.hex:
avrdude: load data flash data from input file avr_chatter.hex:
avrdude: input file avr_chatter.hex auto detected as Intel Hex
avrdude: input file avr_chatter.hex contains 9336 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.37s



avrdude: verifying ...
avrdude: 9336 bytes of flash verified

avrdude: safemode: Fuses OK

avrdude done.  Thank you.

Running the Code

Time to make it all run. Hook up your Atmega32u4 through your level shifter to your PC's serial port. In a terminal window launch roscore:

roscore

Next, start the rosserial client (replace /dev/ttyS0 with the serial port your AVR is connected to):

rosrun rosserial_python serial_node.py /dev/ttyS0

And watch the incoming messages:

rostopic echo chatter

Congratulations! You now have an AVR capable of communicating with your ROS nodes!

ROS 2 Documentation

Wiki

Page

User

Using rosserial with AVR and UART

Source Code

Prerequisites

AVR Development Environment

Hardware

Setting Up the ROS Package

New Modules

avr_time

avr_uart

Implementing rosserial_client

Defining the Hardware Interface

Writing a rosserial Chatter Node

Generating the ROS Message Headers

Makefile

Building the AVR Program

Running the Code