16. System Integration¶
Weekly Digest (Thu. May 16 to Wed. May 22)¶
| Date | Time | Place | Activities |
|---|---|---|---|
| Fri. May 17 | 10:00-12:00 | Office (NID) | Desk Survey on Buzzer Circuit |
| 22:00-01:00 | Home (Nagaoka) | Circuit Simulation on Buzzer, Website Reconstruction and Debugging | |
| Sat. May 18 | 16:00-19:00 | Home (Tokyo) | Debugging cont’d and Documentation on the Buzzer Circuit Simulation |
| Sun. May 19 | 10:00-20:30 | FabLab Kannai | Local Session for Week16 (Work on the Final Project) |
| Mon. May 20 | 10:00-16:00 | Office (NID) | 3D Design of the box mount of the development board, revision of the System Diagram and BOM |
| 21:00-24:00 | Home (Nagaoka) | Revision of the Final Project Documentation | |
| Tue. May 21 | 14:00-18:00 | Office (NID) | Research on Leather Crafting and 2D Design of the packaging for Final Project, 3D Design and Printing of the box mount |
| 19:00-23:00 | Home (Nagaoka) | Documentation on the Local Session for Week16 | |
| Wed. 14:00-17:00 | Office (NID) | Redesign of the box mount and 2D design of the clutch bag for Final Project |
Individual Assignment¶
Here is the list of individual assignments given by the instructors:
- Design and document the system integration for your final project
0. Review of the Final Project Page¶
Towards the presentation on the Final Project, I thought that the descriptions on the Final Project page were becoming obsolete and need updating. Also, before I reached the final design, I did a series of trials-and-errors and wrote about them in just one Final Project page. It’s becoming so messy and so I decided to reorganize the Final Project page:
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TOP: Top page “1. Passport Anti-Theft Alarm Project “IT’S ME”” is only for the summary of the Project, and I will only write about the final specifications of my project.
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Sub-pages: I created a few branch sub-pages so that I could document my iteration on various issues. My trials-and-errors and findings of the desk research are documented here. Also, many of my activities for each week seem to have something to do with my Final Project and I will add a few notes to each of the Weekly Assignment pages.
1. PCB Mounting¶
1-1. Circuit Design¶
For packaging, I should finalize the PCB design of my device. Before the Week16 local session, I did a circuit simulation with Tinkercad and came up with an idea for the circuit. (Please note that the following figure shows my circuit design but I will use Raspberry Pi Pico W instead of Arduino Uno 3. Tinkercad Circuit did not have a Pico W icon.)
Based on this circuit design, I prepared the circuit on the breadboard during the local session. In consultation with the instructor, I connected the battery module as an external power supply.
Since the output voltage of the RPI Pico W is 3.3V, I needed to place a voltage regulator between the battery module and the controller. Also, it was reminded that during the last global session, Neil reminded that for external power supply, capacitors should be attached. So I put two capacitors to voltage in and out of the regulator.
1-2. PCB Design¶
Next, looking back at what I learned in Week8 “Electronics Design”, I designed the schematics and then proceeded to the PCB board design with Fusion360 Electronics.
I made the above schematic design. The battery modules and the piezo buzzer were replaced by the 2-pin sockets. Also, I would like to emphasize that with the RPI Pico W placed in the middle, I put the power supply module on the left and the buzzer module on the right, hoping that this arrangement would make the wire-routing work as simple as possible.
Wi-Fi Module: One thing to note about the PCB design for wireless communication is that we should remove the copper underneath the Wi-Fi module of the controller. In case of the RPI Pico W, the Wi-Fi module is mounted in a silver square box on the surface and I needed to assign a new layer to draw a rectangle in my PCB design for milling the surface, not cutting.
Once the PCB design was ready, I uploaded the exported PNG files to Mods to create gcode data.
The order of the milling process was: (i) trace with a 1/64 endmill, (ii) Copper Removal with a 1/32 endmill, (iii) Hole with 0.7mm endmill, and (iv) Outline with 0.7mm endmill.
PCB milling process was okay. It took 40 minutes to get the PCB board cut. Then I soldered the parts. It was a review of what we learned in Week4 “Electronics Production”.
Lesson Learned: One lesson I would like to share with the readers is that we should be more careful about the position of the controller. We must not forget that the USB cable connectors are usually thicker than the thickness of the controller and the PCB board. I had been taking it easy and then found it was difficult to plug the USB cable deeply into the socket. I was forced to cut the edge of the PCB board with a ultrasonic cutter and that makes my board look ugly.
Anyway, back to the assembly process. After the soldering works, I put the piezo buzzer and saw if we could get the sound. Went well.
1-3. Design of the PCB Mount¶
Following the PCB board design, based on the dimension of the board, I started designing the PCB mount on which both the piezo buzzer and the battery module could also be mounted.
The basic principle of the design is:
- Thickness: It should be as thin as possible. Currently the mount is as thick as 8mm. But once the buzzer is mounted, the total height would be 9.76mm. In addition to this box, I need to design the cover. The thickness of the PCB mount with the cover is expected to not exceed 10mm. The cover should have a hole for the buzzer.
- Size: Initially, I had been thinking of making a device small and thin enough to be inserted into the clear passport cover. However, I realied that it would be a daunting task to reduce the size to that level. Instead, for the Final Project, I am thinking of making the whole system package look like a cover or a bag to put the device and the passport together. For this, the size of the PCB box mount should not exceed that of the passport: 125mm x 88mm.
But I found that if I just place all the components in a row, the width of the box mount might end up with being a bit longer than the passport. Therefore, I redesigned it so that there should be an overlapping area between the PCB board and the piezo buzzer.
I did the test 3D-printing with the following design. On the morning of Wednesday, May 22, I got the result.
Both the battery module and the piezo buzzer looked perfectly fit, it seemed that the wiring routes from these two modules to the main board were tight and the users might find it difficult to mount everything in the box just as I expect. Since the depth of this box (60mm) is much shorter than that of the passport (88mm), I have decided to work on the second design making the wiring route for the battery module a little wider by increasing the depth of the box by 10mm.
Also, the bottom of the box had rough surface.
As of the commencement of Week17, the following is the 2nd version of the box. I also designed the cover for the board.
2. Leather Wallet Design¶
In parallel to the design of the PCB mount, I worked on the design of the leather wallete to put the device box and the passport together.
After the Fab Academy, I am expecting the users to experience as many digital fabrication machines as possible at the local FabLab near them, learn about the potentials of those machines and come up with a lot of ideas on the customized solutions to the problems they are facing locally.
At most of the FabLabs and other types of makerspaces, lasercutters are probably the most popular machine for the nobis users. Aiming at bringing the lasercutting process into my design package, I spent time considering what could be done with a lasercutter. After a few thoughts, I decided to use the leather as a material to make a wallet to put the device box and the passport together.
Leather work requires a lot of instruments, including chisels with a mallet and blades. They are primarily for cutting the pattern papers and then cutting leather along the pattern papers, smoothing the edges of the leather and drilling holes for threading. We cannot do drilling works without creating annoying noises of hammering a gimlet with a mallet. Most of these processes could be replaced to some extent by the lasercutter.
There are many passport holders made of leather already available in the market. But there are very few bag options for the device box together. So I drew two sketches and compared them.
Of the above two options, I decided to go for the second one. It looks like a business card case and I have one good model with me.
As of Wednesday, May 22, I have prepared the 2D data with Adobe Illustrator while I am studying the leather crafting and collecting the materials for it.
