Summary

The device senses the vibration of a smartphone and lights up LEDs in different colors according to the vibration time. Different vibration patterns can be set for each notification to see the type of notification visually.

Purpose

Programming a microcontroller using the C language.

Idea

Smartphones and mobile phones receive a variety of notifications. They also have mechanisms to notify users — for example, alarms, vibrations, and LEDs. However, as of 2014, I routinely set the device to silent mode, so I could not recognize what kind of notification I received by sound. In addition, the LED built into the device is small and difficult to notice. Therefore, I wondered if it would be possible to develop a device that would make it easier to recognize the receipt of messages visually.

Development Environment

An Arduino should be used for easy programming, but I took on the challenge of programming a microcontroller in pure C since I had no experience. The microcontroller was an ATtiny26, Atmel Studio was used for development, and the program was written using AVR writer. The circuit board was made with a Stripboard.

Mechanism

This time, development was limited to four types of notifications: (1) e-mail, (2) LINE, (3) incoming calls, and (4) others. I focused on the difference in vibration patterns as a way for the device to distinguish notifications. The number of vibrations is counted for each notification over a certain period of time. Therefore, it is necessary to set the vibration time differently for each notification.

Inclination sensors have a mechanism whereby the angle of the sensor causes the internal iron ball to move and short-circuit between the terminals. When vibration is applied to the tilt sensor, the terminals are repeatedly short-circuited and un-circuited at high speed, generating pulse waves. The number of pulses in a certain period of time is counted, and the notification type is recognized according to the count value.

LEDs light up in colors according to the vibration mode; LEDs blink gently in a cyclic fashion. The user can visually recognize the type of notification received by the device's color.

Experience

• Experience in developing microcontrollers in C language

• When working in a development environment used for the first time, it is more efficient to check sensor operation on a familiar programming language like Arduino and then move to the actual environment during the implementation stage.

• By building a microcontroller circuit board, I realized that several functions are already integrated into a ready-made microcontroller board.