Now – lets start with the previous draft which is a PCB 120mm wide. The box have room for two of these opposite eachover, so…
Lets add sub-modules that are 60 x 20mm – that is sufficient for a small MCU and fully Galvanic CAN + a Module connector and a M12-5 etc.
And then we add the sub-module in pos 8 up-side down to fill the gap left by the first board. I will need to 3D print a support plate where the sub-modules plug in, but in theory I could have one motherboard and 8 sub-modules in a waterproof box.
This might just work – it enables me to make the best of the base board and add sub-modules to extend the box with very straight forward assembly. The sub-modules can also use more space as needed for more advanced sub-modules. It will be a fiddle to get the 3D plate right so that M12 holes match. As for heat dissipation I can add heat dissipation into the surrounding box using termo rubber – which will add to the stability against vibration as well.
This last drawing indicate the position between the two boards and how M12’a will align, so I have between 3-4mm to adjust using a 3D printed top plate. The drawing below illustrate the top PCB adapter that can support 8 sub-modules – in reality that will be max 6 sub-modules since power and Ethernet will be on the main board as minimum. You also hve the option to use more than one position for a sub-module etc. In the example of the PCB with 3 x CAN we just add sub-modules with CAN in position 2,3 and 8 to have a 6 port CAN that can support NMEA2000 or other CAN standards.
Next time you see this will be an actual box with modules mounted – At this point I need to make the boards and adjust the plate as I mount it. But, what I like here us that this is click & play. You screm on a sub-module, attach a cable to the motherboard and that’s it. I will add code to auto-identify sub-modules and download firmware. The CAN Sub-Module in special is nice because I want a main board with only Power and Ethernet and let the rest be sub-modules. I can also use this technique with other connectors.