binlight

Firmware for ATtiny13(A) and ATtiny85 (and probably other AVRs) -based flashlight drivers. It is written in AVR assembly and includes some some unusual features while still fitting in the meager 1KiB of flash program memory on the ATtiny13A.

Features

• On or off -time based standard mode switching.

• "Quick modes" which can be directly entered from any other mode by a sequence of quick consecutive button taps.

• Configurable multi-level low-battery brightness limiting and periodic indication blinks.

• The following "special function modes" with input/output performed with binary sequences of button taps/light flashes.

  • battery voltage readout
  • read data at any location in EEPROM
  • write data to any EEPROM location
  • temperature readout
  • "hand warmer" mode to maintain target temperature
  • measure and set new off-time

  The UI is pretty rough. Input and output is binary, and voltage and temperature readouts are raw ADC values which you can then calculate the voltage and temperature in degrees from based on component values used.

  By changing the bytes in EEPROM with the eeprom_write special function, almost all configuration values, including mode settings, can be changed on the fly without reprogramming.

  The binary-based input/output interface is arguable a bit ridiculous, but it may amuse one's inner hacker.

binlight was initially written for the ATtiny13A-based Mountain Electronics MTN-10DD driver board. This 10mm diameter board uses an ATtiny13A in the 10-MLP (10-VFDFN) package which cannot be easily connected to for in-circuit programming the way the common 8-SOIC package can with a SOIC clip. The inconvenience of having to reflow the chip from the board for every firmware change inspired the high level of run-time configurability of this firmware.

License

binlight is completely free and public domain. See the LICENSE file.

Requirements

• avr-gcc
• avr-libc (Only for preprocessor macros: avr-libc is not linked with the program.)
• avr-binutils
• avrdude (for flashing the microcontroller)

Building

Ensure the required dependencies above are installed. Change the line

MCU ?= attiny13a

in the Makefile if you are using a different microcontroller than the ATtiny13A. See --mmcu option documentation in man 1 avr-gcc for the list of microcontroller names.

Then run make to generate the Intel hex (.ihex) files that can then be flashed to the microcontroller.

Flashing

Change the line

AVRDUDE_MCU ?= t13

in the Makefile if you are using a different microcontroller than the ATtiny13A. Run avrdude -p ? to get the list of avrdude microcontroller names.

Change the line

PROGRAMER ?= usbasp

in the Makefile if you are not using a USBASP AVR programmer. Run avrudude -c ? to get the list of programmer names.

Then run

# make flash

To flash the program memory, eeprom, and fuses, or

# make flash-program

to flash just the program memory, or

# make flash-eeprom

to flash just the EEPROM

Usage

See doc/usage.md for an explanation of how to use the modes and special functions.

Configuration

See eep_core.S and eeprom.S for the configuration values that are stored in EEPROM. These values are possible to change at run-time by using the eeprom_write special function. You can also just change eep_core.S or eeprom.S and flash your changes by running make flash-eeprom.

Some configuration values were considered not worth making reconfigurable in EEPROM or do not make sense to make reconfigurable in EEPROM (eg pin connections). These are just #defined near the top of main.S.

Hacking

See doc/hacking.txt for some background and information on the theory of operation. See doc/TODO.txt for a list of some features and improvements that I think could be useful (or at least amusing) to implement.

Bugs

Please send any bugs, suggestions, questions, comments, etc to [email protected]

Learning AVR assembly

In addition to the part datasheet and the AVR Instruction Set Manual, these are some resources I found helpful in learning to program AVRs in assembly:

• http://www.elektronik-labor.de/AVR/KursAssembler/T13asm13.html
  • A cute tutorial which also includes a brief introduction to the actual machine code and the SPI programming protocol.
  • In German, but I found the Google Translate English translation mostly usable.
    • Sometimes the opcodes and stuff in the assembly source get translated, so one may want to cross-reference the untranslated version's program listings.
  • Does not use GNU as / avr-gcc, so you will want to reference the GNU as manual: https://sourceware.org/binutils/docs/as/ (or info as).
    • In particular, the AVR Dependent Features section: https://sourceware.org/binutils/docs/as/AVR_002dDependent.html#AVR_002dDependent
• http://www.nongnu.org/avr-libc/user-manual/assembler.html
  • Example of how to use avr-gcc and avr-libc for assembly.