Go into the Preferences panel of the Arduino IDE, and check verbose output on compile. Close the panel and restart the IDE. When you compile the firmware, you will see the path and name of the hex file in the output window, just before the line telling you how many bytes were used. It will look something like this:
I see, thanks! I'm trying to compile the source from the repo (unaltered) and receiving a number of errors. I'm using Arduino IDE and have the board set to ATtiny85 (internal 8 Mhz clock) and the Programmer set to USBTinyISP.
Here is what I'm seeing
In file included from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Stream.h:26,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/libraries/SoftwareSerial/SoftwareSerial.h:36,
from adafruit_usbpowergauge.ino:18:
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Print.h:32:1: warning: "BIN" redefined
In file included from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/iotn85.h:38,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/io.h:284,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/pgmspace.h:82,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/WString.h:29,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Print.h:26,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Stream.h:26,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/libraries/SoftwareSerial/SoftwareSerial.h:36,
from adafruit_usbpowergauge.ino:18:
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/iotnx5.h:55:1: warning: this is the location of the previous definition
adafruit_usbpowergauge.ino: In function 'void setup()':
adafruit_usbpowergauge.ino:87: warning: only initialized variables can be placed into program memory area
adafruit_usbpowergauge.ino:96: warning: only initialized variables can be placed into program memory area
adafruit_usbpowergauge.ino:98: warning: only initialized variables can be placed into program memory area
adafruit_usbpowergauge.ino: In function 'void loop()':
adafruit_usbpowergauge.ino:139: warning: deprecated conversion from string constant to 'char*'
adafruit_usbpowergauge.ino:144: warning: deprecated conversion from string constant to 'char*'
adafruit_usbpowergauge.ino:148: warning: deprecated conversion from string constant to 'char*'
adafruit_usbpowergauge.ino:150: warning: deprecated conversion from string constant to 'char*’
In file included from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Stream.h:26,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/HardwareSerial.h:28,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Arduino.h:193,
from analog.cpp:15:
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Print.h:32:1: warning: "BIN" redefined
In file included from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/iotn85.h:38,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/io.h:284,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/pgmspace.h:82,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Arduino.h:8,
from analog.cpp:15:
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/iotnx5.h:55:1: warning: this is the location of the previous definition
In file included from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Stream.h:26,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/HardwareSerial.h:28,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Arduino.h:193,
from charlie.cpp:16:
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Print.h:32:1: warning: "BIN" redefined
In file included from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/iotn85.h:38,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/io.h:284,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/pgmspace.h:82,
from /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Arduino.h:8,
from charlie.cpp:16:
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/include/avr/iotnx5.h:55:1: warning: this is the location of the previous definition
/Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/lib/avr25/crttn85.o:(.init9+0x2): relocation truncated to fit: R_AVR_13_PCREL against symbol `exit' defined in .fini9 section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_exit.o)
adafruit_usbpowergauge.cpp.o: In function `printDotDecimal(unsigned int, unsigned char)':
/Users/cam/Applications/adafruit_usbpowergauge.ino:117: relocation truncated to fit: R_AVR_13_PCREL against symbol `__udivmodhi4' defined in .text.libgcc section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_udivmodhi4.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:117: relocation truncated to fit: R_AVR_13_PCREL against symbol `Print::print(unsigned int, int)' defined in .text._ZN5Print5printEji section in core.a(Print.cpp.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:120: relocation truncated to fit: R_AVR_13_PCREL against symbol `__udivmodhi4' defined in .text.libgcc section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_udivmodhi4.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:121: relocation truncated to fit: R_AVR_13_PCREL against symbol `__udivmodhi4' defined in .text.libgcc section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_udivmodhi4.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:121: relocation truncated to fit: R_AVR_13_PCREL against symbol `Print::print(unsigned int, int)' defined in .text._ZN5Print5printEji section in core.a(Print.cpp.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:125: relocation truncated to fit: R_AVR_13_PCREL against symbol `__udivmodhi4' defined in .text.libgcc section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_udivmodhi4.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:125: relocation truncated to fit: R_AVR_13_PCREL against symbol `__udivmodhi4' defined in .text.libgcc section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_udivmodhi4.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:125: relocation truncated to fit: R_AVR_13_PCREL against symbol `Print::print(unsigned int, int)' defined in .text._ZN5Print5printEji section in core.a(Print.cpp.o)
adafruit_usbpowergauge.cpp.o: In function `loop':
/Users/cam/Applications/adafruit_usbpowergauge.ino:134: relocation truncated to fit: R_AVR_13_PCREL against symbol `__mulsi3' defined in .text.libgcc section in /Users/cam/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/avr25/libgcc.a(_mulsi3.o)
/Users/cam/Applications/adafruit_usbpowergauge.ino:134: additional relocation overflows omitted from the output