This is a kickoff of my build of a portable Pi. This blog is not attempting to create a Ben Heck Show style documentary, it is just intended to provide some insight into my design and how I am going about the project.
I have been holding off on starting this project for a couple of main reasons.
The first reason is I wanted to test whether my version of the build could be completed in two weeks. I am busy with other things as well, but that is always the case. Lets see, on the personal front – I have to design 3 PCBs for other projects in the next 2 weeks, I am in the final 10 days of the Pi Chef design challenge so there is lots of work to do there, I am working on 2 new project applications, my winter softball team is in the middle of its 3 week playoffs, my hockey season is in its final week and the next season starts the following week. I can't take time off from work because we have 2 major projects with heavy deadlines in the next month plus 2 critical proposals due this week.
The second reason for holding off is that my design depends on having the build kit in hand, as I need to measure every part. Some dimensions are available online but not enough to complete my design.
My version is attempting to closely implement Ben and Felix's cool design of a portable gaming Raspberry Pi. It will use most of the same electrical components and all the same software as Felix and Ben's design. Where this design deviates is that it will make all interconnections on a single printed circuit board, which should make assembly much simpler. This will likely require the housing to be redesigned as the height of everything is pretty much dictated by the PCB.
The first step is collecting all the information about the design into a series of directories. This involve:
- links to the BHS YouTube build
- all the data on their Git Hub repository
- all the data sheets from the internet
- all the images of various components
The first snag I have to overcome is I can't read much of the Git Hub data.
Some of the datasheets won't load in any of my pdf viewers, but that is not a huge issue – I can find the datasheets elsewhere online.
I think I have the stl files okay, but likely won't use them as my design will have some slight changes to positions of some components.
More serious is that I can't read the Eagle files. I am running V6.5 and it cannot load the newer files. Both of the Eagle viewers I tried also failed to read the files. I can figure out most of the connections for the display, so I can recreate much of the schematic without too much effort, however I need to use the same button schematic for the software to work and this isn't on any datasheet. I have reverse engineered the PCB layout from the artwork image so I know what switches are connected to each row and column and where all the diodes go, but I will have to wait for the parts kit to arrive to figure out if my pin assumptions are correct for connection to the Pi, although I doubt the kit will actually have anything that explains it.
For the audio, I have found the datasheet for the Pi audio/video connector, but it does not indicate which pin is which, so again I have to wait for the kit and I may have to break the connector to figure that out. The Adafruit cards are fairly well documented, but not all the pins I need are dimensioned – so another reason why I need the kit.
The kit is in transit so I expect to make progress on the PCB design and hopefully complete it at couple of days after the kit arrives. I can't afford to have the PCB printed in one day, so I will try a service that has arrived in 6 days in the past. It can take longer though so timing is a monumental risk in this build. If the kit arrives tomorrow, it leaves 10 days to complete the design, build, test and documentation video. It is unlikely the PCB shop will start their build before Monday, which would only leave 7 days, so the probable best case scenario is I would get the PCB back at noon on the day the final video is due at 11:00 am. Not good odds, but blithely ignoring them, here is roughly how the components will lay out on the PCB – the USB hub and power module will be under the interconnect PCB, the display ribbon will have to fold back, or I may flip the display breakout card over and move it up to ease routing: I'm still not sure if I will move the speakers - they currently seem hidden by the hands, but there isn't much room elsewhere.
I will likely use different switches because the ones in the original design looked a little wonky.
Once the PCB is on order I can start designing the case to fit it.
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