First iteration prototype Crumpler 1.0 

Write up of some of the details from the Crumpler Prototype I created for testing after a proof of concept prototype had been made and tested.

crumpler bag

Details: iteration 1.0 This change was the first proposal after working through the proof of concept prototype there were issues to address and further investigate. Initial changes from the testing prototype bag was removing the LCD screen, because I was trying to scale down and wanted the simplest of communication with the user. The following table is the items that were used to build this bag. There was a period of testing different circuit boards for their compatibility, programmability and aesthetics. After researching the available components at this time the LilyPad series of items seemed the most relevant as it offered a way to use components that could be attached to the outer surface of the bag, therefore leaving the bulk of the bag mostly unaltered. No compromise on space or weight for the original bag.

 USB LiPoly Charger to charge 3.7V LiPo cells at a rate of 500mA or 100mA per hour. It is designed to charge single-cell Li-Ion or Li-Polymer batteries. The board incorporates a charging circuit, status LED, selectable solder jumper for 500mA or 100mA charging current, external LED footprint, USB input, mounting holes. There is also a ‘SYS OUT’ which allows you to connect the charging circuit directly to your project so you don’t need to disconnect the charger to use.This is a very slow way to charge the batteries, and this is an issue that will need to be addressed. 
 LilyPad Buzzer This is a small buzzer, use 2 I/O pins on the LilyPad main board and create different noises based on the different frequency of I/O toggling. Loud enough to hear inside a pocket but not obtrusively loud. 20mm outer diameter Thin 0.8mm PCB 
 SLO18 RFID reader 5V Supports Mifare 1K, Mifare 4K and Ultralight. It does auto Real-time detecting tag which moves into or out of detective range and reports through one output pin’s logic level. In addition, it integrates all necessary components and antenna in one PCB. Frequency : 13.56MHz Protocol : ISO14443A Tag supported : Ultralight, Mifare Mini, Mifare 1K, Mifare 4K, FM11RF08 Interface : I2C Supply voltage : 4.4 – 7.0VDC Dimension : 65 × 45 mmUsing this RFID reader would mean finding a board suitable to work with the 5V requirement. 
 Polymer Lithium Ion Battery – 6AhrEach cells outputs a nominal 3.7V at 2000mAh – 3 cell pack (6Ahr) is terminated with a standard 2-pin JST-PH connector – 2mm spacing between pins.The 3.7V may be an issue that needs looking into – to get enough power to the board to light the LEDs/ 
 Lilypad 328 Main Board has more I/O ports to access and use for tags / LEDs and operated at 5v so the reader choice had to meet with the same voltage.It has an ATMega328 and Arduino bootloader. It supports automatic reset 55mm outer diameter 0.8mm PCB 
 Slide Switch Simple slide switch to power ON/ OFF the bag. It can be used to switch other things, but that is it’s purpose for this bag. 7.75×18.1mm Thin 0.8mm PCB 
 FTDI basic Breakout 5V This is only needed for programming the board, and can be used with all the 5V boards to program. USB to serial IC. The pinout of this board matches the FTDI cable to work with official Arduino and cloned 5V Arduino boards. It can also be used for general serial applications. The major difference with this board is that it brings out the DTR pin as opposed to the RTS pin of the FTDI cable. The DTR pin allows an Arduino target to auto-reset when a new Sketch is downloaded. This is a really nice feature to have and allows a sketch to be downloaded without having to hit the reset button. This board will auto reset any Arduino board that has the reset pin brought out to a 6-pin connector. This board has TX and RX LEDs. 

Details of Testing Programme

This prototype is a departure from the first proof of concept bag. It was carried around on all my daily journeys to test the bag initially for working issues, sociability and general fixes that would need to be done before testing it with a user.

Results and Conclusions for next Iteration

This bag I used on a daily basis from March 2013 until May 2013, and then less frequently due to moderations / user testing from June –July 2013. The bag is used daily highlighted a lot of issues. Comments from this time period: The importance of the placement of the on / off switch – it was hit accidentally a few times, and I didn’t realise some times – so moving it to better placement / alternative, and maybe adding a vibe board to alert the user that the bag had switched on, so if it was knocked then they would be made aware. With this first iteration, due to the much larger amount of LEDs (the first system had 5 this one has 13), I would have to place a small card in the bag to remind the user of the items and the corresponding colours as there were a lot of LEDs.

This doesn’t seem as practical and I did have people asking me how I would / or how someone would remember the LEDs and what they were for. This needs addressing. The battery weight and charging would need to be addressed, there isn’t a clear way currently to be aware if the bag is low on battery power or how long it needs to charge. After using the bag, I wanted notifications to be more intense the nearer to the time the event / leaving etc, happened… this is scope for future work and implementation because I’m not sure how this could work.

There was an occasion where I had forgotten my student card and I needed it so as I was leaving it would have been good to have gotten a more urgent notification of some sort. Perhaps indicating the importance of the item/use or urgency. I was trying to maximize the number of tags that could be read, but I think this would overload a user. Lastly, it does work in the rain and the battery casing is inside the bag so there is no issue from that aspect too.