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Joined 2 年前
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Cake day: 2023年7月4日

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  • The easy version would be to feed it 5V current

    You could cut or de-solder the ribbon cables and power the upper board alone connecting the +5V and GND wires on the left ribbon to an appropriate power supply. If the upper board isnt blown you might be able to get it to work.

    This kind of two board design is quite common. The bottom PCB is a mixed high + low voltage board that includes the mains power supply with bridge rectifier, transformer and smoothing caps. It sends low voltage power to the upper board via the ribbon.

    The upper board is entirely low voltage and has a microcontroller, display, buzzer and the control knob. Sensors and switches in the oven are passed over the ribbon to the controller, and control signals are passed back through the ribbon to the relays on the power board which then switch high voltage power to bulbs, fans, and other stuff.

    As long as you don’t connect it to mains power it’s a safe low voltage in this case, there is nothing on this board that will generate high voltage from 5V. Don’t leave it powered when you’re not there, low voltage can still burn your house down!

    The more complicated version would be to also reprogram the chip

    This is unlikely, but you never know. Its probably a custom pre-programmed chip that can’t be erased, or at the least it has been locked so it can’t be modified or have the software read out. It’s possible that it could be programmed in place on the board without de-soldering.

    Interestingly the upper PCB also seems to have something that looks like an SPI port (P21) it’s possible this controls something in the oven but I doubt it. It could be a programming interface but SPI is not typically used for that, maybe a test interface? Hard to say. (edit on 2nd thoughts it probably is a programming interface)

    Someone with good electronics / software skills could replace it with an equivalent blank programmable CPU and program it (with something), but that would be a big project even for experienced engineers. Mostly the lack of detailed info about the hardware usually makes it easier to design something new from scratch than to reverse engineer somone elses design.









  • A Raspberry Pi 3 Model B

    It’s connected to my 3d printer and runs octoprint allowing me to upload print jobs. and control the printer from my home network.
    It serves up the Pi camera video stream.
    It can also switch the printers light on and off.

    No cluster setup.




  • This seems strangely just a little bit wrong.

    As mentioned there’s no units on STL files so the slicer assumes millimeters but warns you if it thinks the scaling is obviously not right.

    My blender units are meters.

    If I just export the default cube from blender (which is 2x2x2) and load it up in the slicer I get a prompt saying the units seem to defined in inches. It’s assuming I can’t possibly want to print a 2mm wide cube. Do I want to convert it to inches?

    If I answer No, I get a perfect 2mm cube, good luck printing that. If I choose Yes, to convert it then I get a cube 50.8mm across. (2x 25.4mm) exactly 2 inches as expected.

    Going back to blender, deleteing the default cube and creating another cube but scaled to 0.1m. This time exporting to STL on the export save dialog there is a scale setting: set this to 1000 (to convert from blender 1m units to Prusa 0.001m units). Now the STL is imported into the slicer with no fuss and is exactly a 100mm cube.

    It seems I can’t recreate your problem.


  • If you had this much buffer memory what are the reasons to have swap space as well?

    Many programs do stuff once during startup that they never do again, sometimes creating redundant data objects that will never get accessed in the configuration its being run in. Eventually the kernel memory manager figures out that some pages are never used but it can’t just delete them. If swap is enabled it can swap them to disk instead. It frees up that RAM for something more important. It’s usually minor but every few MB helps.