Assignment Thirteen: Write up the final project as an application

This week's task is to write up the final project using skills we have learnt so far in the course. From my final project page, I have slowly arrived at my project concept which is to make small devices that can record and play sound for a limited time.

How I arrived at this project concept is based on some design research I've been doing on long distance relationships, trying to understand how couples cope without each other - and trying to see if there are products that could improve this. I decided on little sound devices that can record messages to be played and stored anywhere.

The assignment in steps:

Full Concept
Electronics System
Mechanical Enclosure
Spiral Development and Timelines

Full Concept

In a long distance relationship, many couples can not go to interesting places with their partner so they go alone. A recorded diary would be beneficial to help take notes of what a partner is experiencing. When that note has been taken, it can then be played by the other person.

Initially, my concept was a device that can send a signal to another one over very long distances - from one continent to another - but the best way for such a system would be GSM/GPRS but then the devices would need to have a SIM card. I didn't want the devices to be connected to wifi either as people could move around.

Electronics System

The system is to have the following use cases: a user can record a voice note which is then saved automatically. Recording another voice note erases the previously saved voice note. The voice note will also be able to be played.

So, the idea is to have:

• A microphone to record the sound
• A microcontroller to time how long the recording can be
• A speaker to play the recording
• A button that uses events to control modes
• A memory (SD) card to save the recordings
• LEDs that show for different modes: recording, playing

Mechanical Enclosure

The enclosure will be made from urethane casting and 3D printing. I plan to make it a press fit assembly so that the SD card can be removed at any time. I also want to have openings in the design so that sound can be picked up by the microphone and heard from the speaker.

Spiral Development and Timelines

The assignments for Input Devices and Output Devices will serve as two spirals for me and the other parts of the work will be done progressively.

Spiral 1 - Record and see sound played from the board / Week 11, Input Devices

Spiral 2 - Play sound already recorded with the same board / Week 12, Output Devices

Spiral 3 - Play sound from an SD card and save recorded sound to an SD card

Spiral 4 - Add LEDs and one or more buttons to control the recording and playing modes

Spiral 5 - Design a circular board that has all these parts and make an enclosure for the whole device