Not just an Arduino powered alarm clock.

View the Project on GitHub fakufaku/TokyoTime

Not just another Arduino based alarm-clock. But much more than that. It has a Two-Wire interface, serial interface, RTC, temperature sensor and a buzzer.

These features make it ideal for all projects where temperature and time are critical like:

In addition it can be powered from a CR2032 battery, or from a 5V wall-wart.

This project builds on the BigTime project by @nseidle, but the whole board was redesigned from scratch.


Checkout the assembly guide here.


The bootloader needed is the "Atmega328 on a breadboard" bootloader available (with instructions) from the Arduino website.

The bootloader add-on files for Arduino IDE are located in firmware/hardware. To install them, simply copy the firmware/hardware to the local Arduino folder.

The TokyoTime doesn't have an ISP header to upload the firmware, so another board must be used to burn the bootloader to the chip. A standard Arduino board can be used.

The fuse should be set automatically when burning the bootloader using Arduino IDE. If not, the fuse should be set to use the internal 8MHz oscillator and disable the brown-out threshold. The fuse can be burnt with avrdude using the following command

-U lfuse:w:0xe2:m -U hfuse:w:0xda:m -U efuse:w:0x07:m


The TokyoTime board features a handy serial header that can be used to upload new code to the chip (provided it has a bootloader) with a 3.3V FTDI-to-USB converter such as this one.

There are so far three different firmware for the board.

Bill Of Material

All the parts can be bought at Akizuki Denshi in Akihabara, Tokyo. Equivalent parts can be found on Mouser, but please check the datasheets to make sure the footprints correspond.


(c) 2011-2014, Robin Scheibler

This work is realeased under the CC-BY-SA 3.0 License.