I am working on an OSHW rugged tablet for which i want to make the PCB modular, hackable and economical for fabrication. To do that i was thinking that i can take an inspiration from OLIMEX's SOM-204 project which is a solution of 2 Printed Circuit Boards ("PCBs") where one PCB is the "Module Board" which has the chip, ram and anything that is specifically relevant to the chip and is usually 4~12+ layers that slots in an "Evaluation Board" which has various connectors, devices, etc.. and is significantly larger in size and 1~4 layers. The idea is that the "module board" can be fabricated in high quantities thus making the cost of fabrication for high layer PCBs not painful (can go as high as 1500+ EUR/USD in low quantities) that can then be slotted in a "platform board" which is a very economical to fabricate (usually around 25 EUR for 5 of them) so it can be adjusted to any formfactor and project and then combined with "module board" from a distributor for the cost of the components + fabrication (usually it's cost of the components + ~10 EUR) And because the "module board" can be basically used for anything this way then it's fabrication in high quantities makes sense economically. But the solution by OLIMEX is limited on 204 pins as it's using DDR3 SODIMM connector with 204 pins where the obvious solution would be to use DDR5 SODIMM which has 262 pins, but i think that there are alternative solutions that would make that platform more functional which i want to brainstorm. So i've written down the issue and ideas in [1]https://git.dotya.ml/kreyren/OSHW-System-On-Module and i want to propose it as standard that people can integrate in their project (thus lowering the cost of "module board" where the cost goes down the more popular the module board is to buy) while enabling anyone to make any OSHW/Free and Open Source Hardware Designs and fabricate them locally for a cost that the generic consumer can afford painlessly. In practice the abstract of making said tablet is:
1. Downloading the libre KiCAD designs for the "platform board" and sending them to local PCB fabricator (~25 EUR for 5 PCBs) 2. Buying the "Module Board" - For reference i bought OLIMEX's A20-SOM ([2]https://www.olimex.com/Products/SOM/A20/A20-SOM) locally for 13 EUR/USD including shipping, first hand costs 35 EUR/USD 3. Download the chasis implemented in OpenSCAD/LibFive (projected to be generatable depending on what devices and configuration the user wants) and put that on a 3D printer (optionally using pre-optimized print to skip the slicer phase and get reproducible results (for technical materials as the chasis is designed to be printed using a PolyPropylen + GF30 which is very difficult to print) 4. Source additional components such as touch screen display, etc.. - Projected to have a list of compatible monitors and mediawiki for people to add where these can be bought locally.. I can get a 10" touch screen display for <5 EUR from a e-recycling center which usually has a lot of them (and the chasis is functional design that can be generated to fit the display), ~30 EUR from second hand and 30-80 EUR online e.g. OLIMEX sells one for 78 EUR [3]https://www.olimex.com/Products/OLinuXino/LCD/LCD-OLinuXino- 10/open-source-hardware 5. Put it all together to get fully libre tablet for ~40 EUR + cost of the components and fillament + 3D print, assuming that people have access to 3D printer or makerspace where they can use one (I have access to the 3D printer for free sponsored by city of Brno to all citizens and local makerspace costs ~5 EUR to use for a day outside of membership or asking makerspace member to let you in and print it for them for the cost of fillament) that you can adjust to any kind of computing you want for ~25 EUR for new platform PCB. Brainstorm, merge requests and anything relevant to the project is very appreciated! -- Jacob "Kreyren" Hrbek References 1. https://git.dotya.ml/kreyren/OSHW-System-On-Module/src/branch/central/README.md 2. https://www.olimex.com/Products/SOM/A20/A20-SOM/ 3. https://www.olimex.com/Products/OLinuXino/LCD/LCD-OLinuXino-10/open-source-hardware
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