/elec/propeller-clock : revision 26

1

# Arduino 0022 Makefile

2

#

3

#

4

# written by olikraus@gmail.com

5

#

6

# Features:

7

# - boards.txt is used to derive parameters

8

# - All intermediate files are put into a separate directory (TMPDIRNAME)

9

# - Simple use: Copy Makefile into the same directory of the .pde file

10

#

11

# Limitations:

12

# - requires UNIX environment

13

# - TMPDIRNAME must be subdirectory of the current directory.

14

#

15

# Targets

16

# all build everything

17

# upload build and upload to arduino

18

# clean remove all temporary files (includes final hex file)

19

#

20

# History

21

# 001 28 Apr 2010 first release

22

# 002 05 Oct 2010 added 'uno'

23

#

24

25

#=== user configuration ===

26

# All ...PATH variables must have a '/' at the end

27

28

# Board (and prozessor) information: see $(ARDUINO_PATH)hardware/arduino/boards.txt

29

# Some examples:

30

# BOARD DESCRIPTION

31

# uno Arduino Uno

32

# atmega328 Arduino Duemilanove or Nano w/ ATmega328

33

# diecimila Arduino Diecimila, Duemilanove, or Nano w/ ATmega168

34

# mega Arduino Mega

35

# mini Arduino Mini

36

# lilypad328 LilyPad Arduino w/ ATmega328

37

BOARD:=diecimila

38

39

# additional (comma separated) defines

40

# -DDOGM128_HW board is connected to DOGM128 display

41

# -DDOGM132_HW board is connected to DOGM132 display

42

# -DDOGS102_HW board is connected to DOGS102 display

43

# -DDOG_REVERSE 180 degree rotation

44

DEFS=

45

46

# The location where the avr tools (e.g. avr-gcc) are located. Requires a '/' at the end.

47

# Can be empty if all tools are accessable through the search path

48

AVR_TOOLS_PATH:=/usr/bin/

49

50

# Install path of the arduino software. Requires a '/' at the end.

51

ARDUINO_PATH:=/home/edam/opt/arduino-0022/

52

53

# Install path for avrdude. Requires a '/' at the end. Can be empty if

54

# avrdude is in the search path.

55

AVRDUDE_PATH:=$(ARDUINO_PATH)hardware/tools/

56

57

# The unix device where we can reach the arduino board

58

# Uno: /dev/ttyACM0

59

# Duemilanove: /dev/ttyUSB0

60

AVRDUDE_PORT:=/dev/ttyACM0

61

62

# List of all libaries which should be included.

63

#EXTRA_DIRS+=$(ARDUINO_PATH)libraries/SPI/

64

#EXTRA_DIRS+=$(ARDUINO_PATH)libraries/Ethernet/

65

#EXTRA_DIRS+=$(ARDUINO_PATH)libraries/Ethernet/utility/

66

67

#=== fetch parameter from boards.txt processor parameter ===

68

# the basic idea is to get most of the information from boards.txt

69

70

BOARDS_TXT:=$(ARDUINO_PATH)hardware/arduino/boards.txt

71

72

# get the MCU value from the $(BOARD).build.mcu variable. For the

73

# atmega328 board this is atmega328p

74

MCU:=$(shell sed -n -e "s/$(BOARD).build.mcu=$.*$/\1/p" $(BOARDS_TXT))

75

# get the F_CPU value from the $(BOARD).build.f_cpu variable. For the

76

# atmega328 board this is 16000000

77

F_CPU:=$(shell sed -n -e "s/$(BOARD).build.f_cpu=$.*$/\1/p" $(BOARDS_TXT))

78

79

# avrdude

80

# get the AVRDUDE_UPLOAD_RATE value from the $(BOARD).upload.speed

81

# variable. For the atmega328 board this is 57600

82

AVRDUDE_UPLOAD_RATE:=$(shell sed -n -e "s/$(BOARD).upload.speed=$.*$/\1/p" $(BOARDS_TXT))

83

# get the AVRDUDE_PROGRAMMER value from the $(BOARD).upload.protocol

84

# variable. For the atmega328 board this is stk500

85

#AVRDUDE_PROGRAMMER:=$(shell sed -n -e "s/$(BOARD).upload.protocol=$.*$/\1/p" $(BOARDS_TXT))

86

# use stk500v1, because stk500 will default to stk500v2

87

AVRDUDE_PROGRAMMER:=stk500v1

88

89

#=== identify user files ===

90

PDESRC:=$(shell ls *.pde)

91

TARGETNAME=$(basename $(PDESRC))

92

93

CDIRS:=$(EXTRA_DIRS) $(addsuffix utility/,$(EXTRA_DIRS))

94

CDIRS:=*.c utility/*.c $(addsuffix *.c,$(CDIRS)) $(ARDUINO_PATH)hardware/arduino/cores/arduino/*.c

95

CSRC:=$(shell ls $(CDIRS) 2>/dev/null)

96

97

CCSRC:=$(shell ls *.cc 2>/dev/null)

98

99

CPPDIRS:=$(EXTRA_DIRS) $(addsuffix utility/,$(EXTRA_DIRS))

100

CPPDIRS:=*.cpp utility/*.cpp $(addsuffix *.cpp,$(CPPDIRS)) $(ARDUINO_PATH)hardware/arduino/cores/arduino/*.cpp

101

CPPSRC:=$(shell ls $(CPPDIRS) 2>/dev/null)

102

103

#=== build internal variables ===

104

105

# the name of the subdirectory where everything is stored

106

TMPDIRNAME:=tmp

107

TMPDIRPATH:=$(TMPDIRNAME)/

108

109

AVRTOOLSPATH:=$(AVR_TOOLS_PATH)

110

111

OBJCOPY:=$(AVRTOOLSPATH)avr-objcopy

112

OBJDUMP:=$(AVRTOOLSPATH)avr-objdump

113

SIZE:=$(AVRTOOLSPATH)avr-size

114

115

CPPSRC:=$(addprefix $(TMPDIRPATH),$(PDESRC:.pde=.cpp)) $(CPPSRC)

116

117

COBJ:=$(CSRC:.c=.o)

118

CCOBJ:=$(CCSRC:.cc=.o)

119

CPPOBJ:=$(CPPSRC:.cpp=.o)

120

121

OBJFILES:=$(COBJ) $(CCOBJ) $(CPPOBJ)

122

DIRS:= $(dir $(OBJFILES))

123

124

DEPFILES:=$(OBJFILES:.o=.d)

125

# assembler files from avr-gcc -S

126

ASSFILES:=$(OBJFILES:.o=.s)

127

# disassembled object files with avr-objdump -S

128

DISFILES:=$(OBJFILES:.o=.dis)

129

130

131

LIBNAME:=$(TMPDIRPATH)$(TARGETNAME).a

132

ELFNAME:=$(TMPDIRPATH)$(TARGETNAME).elf

133

HEXNAME:=$(TMPDIRPATH)$(TARGETNAME).hex

134

135

AVRDUDE_FLAGS = -V -F

136

AVRDUDE_FLAGS += -C $(ARDUINO_PATH)/hardware/tools/avrdude.conf

137

AVRDUDE_FLAGS += -p $(MCU)

138

AVRDUDE_FLAGS += -P $(AVRDUDE_PORT)

139

AVRDUDE_FLAGS += -c $(AVRDUDE_PROGRAMMER)

140

AVRDUDE_FLAGS += -b $(AVRDUDE_UPLOAD_RATE)

141

AVRDUDE_FLAGS += -U flash:w:$(HEXNAME)

142

143

AVRDUDE = $(AVRDUDE_PATH)avrdude

144

145

#=== predefined variable override ===

146

147

# use "make -p -f/dev/null" to see the default rules and definitions

148

# Build C and C++ flags. Include path information must be placed here

149

COMMON_FLAGS = -DF_CPU=$(F_CPU) -mmcu=$(MCU) $(DEFS)

150

# COMMON_FLAGS += -gdwarf-2

151

COMMON_FLAGS += -Os

152

COMMON_FLAGS += -Wall -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums

153

COMMON_FLAGS += -I.

154

COMMON_FLAGS += -I$(ARDUINO_PATH)hardware/arduino/cores/arduino

155

COMMON_FLAGS += $(addprefix -I,$(EXTRA_DIRS))

156

COMMON_FLAGS += -fno-exceptions -ffunction-sections -fdata-sections -Wl,--gc-sections

157

COMMON_FLAGS += -Wl,--relax

158

COMMON_FLAGS += -mcall-prologues

159

160

CFLAGS = $(COMMON_FLAGS) -std=gnu99 -Wstrict-prototypes

161

CXXFLAGS = $(COMMON_FLAGS)

162

163

# Replace standard build tools by avr tools

164

CC = $(AVRTOOLSPATH)avr-gcc

165

CXX = $(AVRTOOLSPATH)avr-g++

166

AR = @$(AVRTOOLSPATH)avr-ar

167

168

169

# "rm" must be able to delete a directory tree

170

RM = rm -rf

171

172

#=== rules ===

173

174

# add rules for the C/C++ files where the .o file is placed in the

175

# TMPDIRPATH reuse existing variables as far as possible

176

177

$(TMPDIRPATH)%.o: %.c

178

@echo compile $<

179

@$(COMPILE.c) $(OUTPUT_OPTION) $<

180

181

$(TMPDIRPATH)%.o: %.cc

182

@echo compile $<

183

@$(COMPILE.cc) $(OUTPUT_OPTION) $<

184

185

$(TMPDIRPATH)%.o: %.cpp

186

@echo compile $<

187

@$(COMPILE.cpp) $(OUTPUT_OPTION) $<

188

189

$(TMPDIRPATH)%.s: %.c

190

@$(COMPILE.c) $(OUTPUT_OPTION) -S $<

191

192

$(TMPDIRPATH)%.s: %.cc

193

@$(COMPILE.cc) $(OUTPUT_OPTION) -S $<

194

195

$(TMPDIRPATH)%.s: %.cpp

196

@$(COMPILE.cpp) $(OUTPUT_OPTION) -S $<

197

198

$(TMPDIRPATH)%.dis: $(TMPDIRPATH)%.o

199

@$(OBJDUMP) -S $< > $@

200

201

.SUFFIXES: .elf .hex .pde

202

203

.elf.hex:

204

@$(OBJCOPY) -O ihex -R .eeprom $< $@

205

206

$(TMPDIRPATH)%.cpp: %.pde

207

@cat $(ARDUINO_PATH)hardware/arduino/cores/arduino/main.cpp > $@

208

@cat $< >> $@

209

@echo >> $@

210

@echo 'extern "C" void __cxa_pure_virtual() { while (1); }' >> $@

211

212

213

.PHONY: all

214

all: tmpdir $(HEXNAME) assemblersource showsize

215

ls -al $(HEXNAME) $(ELFNAME)

216

217

$(ELFNAME): $(LIBNAME)($(addprefix $(TMPDIRPATH),$(OBJFILES)))

218

$(LINK.o) $(COMMON_FLAGS) $(LIBNAME) $(LOADLIBES) $(LDLIBS) -o $@

219

220

$(LIBNAME)(): $(addprefix $(TMPDIRPATH),$(OBJFILES))

221

222

#=== create temp directory ===

223

# not really required, because it will be also created during the

224

# dependency handling

225

.PHONY: tmpdir

226

tmpdir:

227

@test -d $(TMPDIRPATH) || mkdir $(TMPDIRPATH)

228

229

#=== create assembler files for each C/C++ file ===

230

.PHONY: assemblersource

231

assemblersource: $(addprefix $(TMPDIRPATH),$(ASSFILES)) $(addprefix $(TMPDIRPATH),$(DISFILES))

232

233

234

#=== show the section sizes of the ELF file ===

235

.PHONY: showsize

236

showsize: $(ELFNAME)

237

$(SIZE) $<

238

239

#=== clean up target ===

240

# this is simple: the TMPDIRPATH is removed

241

.PHONY: clean

1

#_______________________________________________________________________________

2

#

3

# edam's arduino makefile

4

#_______________________________________________________________________________

5

# version 0.1

6

#

7

8

#

9

# Permission is hereby granted, free of charge, to any person obtaining a copy

10

# of this software and associated documentation files (the "Software"), to deal

11

# in the Software without restriction, including without limitation the rights

12

# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

13

# copies of the Software, and to permit persons to whom the Software is

14

# furnished to do so, subject to the following conditions:

15

#

16

# The above copyright notice and this permission notice shall be included in

17

# all copies or substantial portions of the Software.

18

#

19

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

20

# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

21

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

22

# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

23

# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

24

# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

25

# THE SOFTWARE.

26

#

27

#_______________________________________________________________________________

28

#

29

#

30

# This is a general purpose makefile for use with Arduino (arduino.cc)

31

# hardware and software. It works with the arduino-1.0 release and

32

# requires that to be downloaded separately.

33

#

34

# There are two ways to use this file, an automatic mode and a manual

35

# mode. In automatic mode, you simply copy this makefile to your

36

# arduino project directory, rename it "Makefile" and type make. The

37

# project directory is expected to contain an .ino or .pde file, which

38

# will automatically be used automatically, along with any other .c,

39

# .cc or .cpp files in the project directory and any subdirectory

40

# named "utility". In this way, this makefile should act as a drop-in

41

# replacement for the Arduino IDE's build process and can build a

42

# project automatically from the files in a project directory.

43

#

44

# Alternatively, you can manually specify what files should be

45

# inclided in a build. To use this makefile manually, you might be

46

# better to keep it somewhere and include it in your project's

47

# Makefile after having defined certain parameters that control the

48

# build. As an example, consider the following Makefile:

49

#

50

# TARGET = my_program

51

# SOURCES = main.cc foo.cc

52

# BOARD = nano

53

# SERIALDEV = /dev/ttyACM0

54

# include ~/src/arduino.mk

55

#

56

# In both manual and automatic modes, the standard Arduino main.cpp's

57

# main() is included, which expects to be able to call init() and

58

# loop() in your code. The main difference is that, in manual mode,

59

# these would typically be placed in a .cc or .cpp file.

60

#

61

# When using manual mode, the following variables can be used:

62

#

63

# TARGET The name of the target file. This is typically the same name

64

# as the project directory for an arduino project and, if

65

# unspecified, that is used as a default.

66

#

67

# SOURCES A list of all source files of whatever language. The language

68

# type is determined by the file extension.

69

#

70

# BOARD Specify a target board type. These are defined in boards.txt,

71

# which came with your arduino installation. If unspecified,

72

# a default is used. (See below).

73

#

74

# SERIALDEV The unix device name of the device where the arduino can be

75

# found. If unspecified, a default is used. (See below).

76

#

77

# This general-purpose makefile also defines the following goals for use on the

78

# command line when you run make:

79

#

80

# all This is the default if no goal is specified. It builds the

81

# target and uploads it.

82

#

83

# target Builds the target of your Makefile.

84

#

85

# upload Uploads the target to an attached arduino.

86

#

87

# clean Deletes temporary files.

88

#

89

# <file> Builds the specified file, either an object file or the target,

90

# from those that that would be built for the project.

91

#

92

#_______________________________________________________________________________

93

# SETTINGS

94

95

# The full path to the arduino software

96

ARDUINODIR := $(wildcard ~/opt/arduino-1.0)

97

98

# The board name to build for and upload to. For a complete list of available

99

# boards, see hardware/arduino/boards.txt in your arduino software directory.

100

# Here is a list of available boards at time of writing:

101

# uno Arduino Uno

102

# atmega328 Arduino Duemilanove w/ ATmega328

103

# diecimila Arduino Diecimila or Duemilanove w/ ATmega168

104

# nano328 Arduino Nano w/ ATmega328

105

# nano Arduino Nano w/ ATmega168

106

# mega2560 Arduino Mega 2560 or Mega ADK

107

# mega Arduino Mega (ATmega1280)

108

# mini328 Arduino Mini w/ ATmega328

109

# mini Arduino Mini w/ ATmega168

110

# fio Arduino Fio

111

# bt328 Arduino BT w/ ATmega328

112

# bt Arduino BT w/ ATmega168

113

# lilypad328 LilyPad Arduino w/ ATmega328

114

# lilypad LilyPad Arduino w/ ATmega168

115

# pro5v328 Arduino Pro or Pro Mini (5V, 16 MHz) w/ ATmega328

116

# pro5v Arduino Pro or Pro Mini (5V, 16 MHz) w/ ATmega168

117

# pro328 Arduino Pro or Pro Mini (3.3V, 8 MHz) w/ ATmega328

118

# pro Arduino Pro or Pro Mini (3.3V, 8 MHz) w/ ATmega168

119

# atmega168 Arduino NG or older w/ ATmega168

120

# atmega8 Arduino NG or older w/ ATmega8

121

ifndef BOARD

122

BOARD := nano

123

endif

124

125

# The name of the serial device that the arduino is at. For example,

126

# /dev/ttyACM0 (Uno), or /dev/ttyUSB0 (Duemilanove)

127

ifndef SERIALDEV

128

SERIALDEV := /dev/ttyACM0

129

endif

130

131

#_______________________________________________________________________________

132

#

133

134

# auto mode?

135

INOFILE := $(wildcard *.ino *.pde)

136

ifdef INOFILE

137

ifneq ($(words $(INOFILE)), 1)

138

$(error You can only have one .pde or .ino file in the directory)

139

endif

140

TARGET := $(basename $(INOFILE))

141

SOURCES := $(INOFILE) \

142

$(wildcard *.c *.cc *.cpp $(addprefix utility/, *.c *.cc *.cpp))

143

endif

144

145

# files

146

OBJECTS := $(addsuffix .o, $(basename $(SOURCES)))

147

ifdef INOFILE

148

OBJECT += main.o

149

endif

150

ARDUINOSRCDIR := $(ARDUINODIR)/hardware/arduino/cores/arduino

151

ARDUINOLIB := _arduino.a

152

ARDUINOLIBTMP := _arduino.a.tmp

153

ARDUINOSOURCES := $(wildcard $(addprefix $(ARDUINOSRCDIR)/, *.c *.cpp))

154

ARDUINOOBJECTS := $(addsuffix .o, $(addprefix $(ARDUINOLIBTMP)/, $(basename \

155

$(subst $(ARDUINOSRCDIR)/,,$(ARDUINOSOURCES)))))

156

157

# obtain parameters from the arduino boards.txt file

158

BOARDS_FILE := $(ARDUINODIR)/hardware/arduino/boards.txt

159

BOARD_BUILD_MCU := \

160

$(shell sed -ne "s/$(BOARD).build.mcu=$.*$/\1/p" $(BOARDS_FILE))

161

BOARD_BUILD_FCPU := \

162

$(shell sed -ne "s/$(BOARD).build.f_cpu=$.*$/\1/p" $(BOARDS_FILE))

163

BOARD_BUILD_VARIANT := \

164

$(shell sed -ne "s/$(BOARD).build.variant=$.*$/\1/p" $(BOARDS_FILE))

165

BOARD_UPLOAD_SPEED := \

166

$(shell sed -ne "s/$(BOARD).upload.speed=$.*$/\1/p" $(BOARDS_FILE))

167

BOARD_UPLOAD_PROTOCOL := \

168

$(shell sed -ne "s/$(BOARD).upload.protocol=$.*$/\1/p" $(BOARDS_FILE))

169

170

# software

171

CC := avr-gcc

172

CXX := avr-g++

173

LD := avr-ld

174

AR := avr-ar

175

OBJCOPY := avr-objcopy

176

AVRDUDE := $(ARDUINODIR)/hardware/tools/avrdude

177

178

# flags

179

CPPFLAGS = -Os -Wall -fno-exceptions -ffunction-sections -fdata-sections

180

CPPFLAGS += -mmcu=$(BOARD_BUILD_MCU) -DF_CPU=$(BOARD_BUILD_FCPU)

181

CPPFLAGS += -I. -Iutility -I$(ARDUINOSRCDIR)

182

CPPFLAGS += -I$(ARDUINODIR)/hardware/arduino/variants/$(BOARD_BUILD_VARIANT)/

183

AVRDUDEFLAGS = -V -F -C $(ARDUINODIR)/hardware/tools/avrdude.conf

184

AVRDUDEFLAGS += -p $(BOARD_BUILD_MCU) -P $(SERIALDEV)

185

AVRDUDEFLAGS += -c $(BOARD_UPLOAD_PROTOCOL) -b $(BOARD_UPLOAD_SPEED)

186

187

# checks

188

ifeq ($(TARGET),)

189

$(error No target defined!)

190

endif

191

192

# default rule

193

.DEFAULT_GOAL := all

194

195

#_______________________________________________________________________________

196

# RULES

197

198

.PHONY: all target upload clean

199

200

all: target upload

201

202

target: $(TARGET).elf

203

204

upload:

205

stty -F $(SERIALDEV) hupcl

206

$(OBJCOPY) -O ihex -R .eeprom $(TARGET).elf $(TARGET).hex

207

$(AVRDUDE) $(ARVDUDEFLAGS) -U flash:w:$(TARGET).hex

208

rm $(TARGET).hex

209

242

210

clean:

243

$(RM) $(TMPDIRPATH)

244

245

# Program the device.

246

# step 1: reset the arduino board with the stty command

247

# step 2: user avrdude to upload the software

248

.PHONY: upload

249

upload: $(HEXNAME)

250

stty -F $(AVRDUDE_PORT) hupcl

251

$(AVRDUDE) $(AVRDUDE_FLAGS)

252

253

254

# === dependency handling ===

255

# From the gnu make manual (section 4.14, Generating Prerequisites

256

# Automatically) Additionally (because this will be the first executed

257

# rule) TMPDIRPATH is created here. Instead of "sed" the "echo"

258

# command is used

259

# cd $(TMPDIRPATH); mkdir -p $(DIRS) 2> /dev/null; cd ..

260

DEPACTION=test -d $(TMPDIRPATH) || mkdir $(TMPDIRPATH);\

261

mkdir -p $(addprefix $(TMPDIRPATH),$(DIRS));\

262

set -e; echo -n $@ $(dir $@) > $@; $(CC) -MM $(COMMON_FLAGS) $< >> $@

263

264

265

$(TMPDIRPATH)%.d: %.c

266

@$(DEPACTION)

267

268

$(TMPDIRPATH)%.d: %.cc

269

@$(DEPACTION)

270

271

272

$(TMPDIRPATH)%.d: %.cpp

273

@$(DEPACTION)

274

275

# Include dependency files. If a .d file is missing, a warning is

276

# created and the .d file is created This warning is not a problem

277

# (gnu make manual, section 3.3 Including Other Makefiles)

278

-include $(addprefix $(TMPDIRPATH),$(DEPFILES))

279

211

rm -f $(OBJECTS)

212

rm -f $(TARGET).elf $(TARGET).hex $(ARDUINOLIB) *~

213

rm -rf $(ARDUINOLIBTMP)

214

215

# building the target

216

217

$(TARGET).elf: $(ARDUINOLIB) $(OBJECTS)

218

$(CC) -Os -Wl,--gc-sections $(OBJECTS) $(ARDUINOLIB) -o $@

219

220

%.o: %.ino

221

$(COMPILE.cpp) -o $@ -x c++ -include $(ARDUINOSRCDIR)/Arduino.h $<

222

223

%.o: %.pde

224

$(COMPILE.cpp) -o $@ -x c++ -include $(ARDUINOSRCDIR)/Arduino.h $<

225

226

# building the arduino library

227

228

$(ARDUINOLIB): $(ARDUINOOBJECTS)

229

$(AR) rcs $@ $?

230

rm -rf $(ARDUINOLIBTMP)

231

232

.INTERMEDIATE: $(ARDUINOOBJECTS)

233

234

$(ARDUINOLIBTMP)/%.o: $(ARDUINOSRCDIR)/%.c

235

@test -d $(ARDUINOLIBTMP) || mkdir $(ARDUINOLIBTMP)

236

$(COMPILE.c) -o $@ $<

237

238

$(ARDUINOLIBTMP)/%.o: $(ARDUINOSRCDIR)/%.cpp

239

@test -d $(ARDUINOLIBTMP) || mkdir $(ARDUINOLIBTMP)

240

$(COMPILE.cpp) -o $@ $<