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I used a Kenmore/Frigidaire microwave oven controller board to teach a class on VFD driving/multiplexing and few other topics. It was well received, but many students wondered if they could find more information specifically about the micro-controller chip used.

Unfortunately no information whatsoever comes up on Google when searching any of the numbers from the chip. Apparently it is proprietary with no publicly available information about it.

This is not the first proprietary chip I came across, but the first one I am really looking forward to find info on. Are there any other sources of information I could tap into to get a datasheet?

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    \$\begingroup\$ No, there is no way unless you have some advanced reverse-engineering tools, insider information and much free time. \$\endgroup\$ – Eugene Sh. Aug 8 '17 at 20:13
  • \$\begingroup\$ Pay hackers or learn how to hack Kenmore data servers? \$\endgroup\$ – Passerby Aug 8 '17 at 20:16
  • \$\begingroup\$ Could you show the numbers on the chip, and/or an image of the chip? \$\endgroup\$ – Reinderien Aug 8 '17 at 22:08
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No. Applications support is costly, especially for microcontrollers. With a house numbered device, most likely this support is provided directly to the OEM (Original Equipment Manufacturer, Kenmore) by a specific account manager contact at the chip vendor (let's say Hitachi for example). Likely it's based on some publicly visible microcontroller like maybe Renesas H8 (wild guess, I could be way off), possibly customized for that large OEM customer. Since the NRE costs (Non-Recurring Engineering) are paid by the OEM, that design belongs to the OEM. Bear in mind that Kenmore has competitors. If OEM 1 specs a custom chip that gives them an advantage like lower cost or more features, they won't make it easy for competing OEM 2 to benefit from their design.

Legions of corporate lawyers protect this kind of proprietary intellectual property information, which is worth millions of dollars of NRE and untold opportunity costs.

Your best bet is to search on "vacuum fluorescent display controller" and select something publicly supported. (Disclaimer: I'm an applications engineer at Maxim Integrated, and apparently several of our display driver chips are near or at the top of this google search.) You may find either display driver chips that require a user-provided microcontroller, or possibly a microcontroller with integrated VFD drivers.

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  • \$\begingroup\$ It's all right, we have a number of Panasonic and LG chips (including a proprietary chip by LG) in the lab to play around. Thanks for clarifying that OEM means Original Equipment Manufacturer, by the way. Much appreciated! \$\endgroup\$ – ajeh Aug 8 '17 at 21:35
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A proprietary chip isn't just used to provide the benefit of reduced cost or added features - it can be an effective way to slow down competitors who might otherwise simply clone a design and benefit from not investing as much time in NRE.

At a minimum the pinout may differ from a standard part with published specs (sometimes this will have been done to reduce PCB cost if routing can be simplified). Even if this is the only change, the specs are unlikely to be public since manufacturers generally prefer to keep as much control of their product design as possible.

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Yes, you can. You can go find a lab with a nice microscope and burn off the epoxy with nitric acid (major safety hazard). After the silicon is exposed you can see if it has any fab markings on it. Then that's kind of the end of the road, because even if you did know the fab, the design will probably be off limits.

You might be able to burn off some other microcontrollers that you think are similar and see if you get a match. Odds are its an ASIC that doesn't have code on it.

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The die might have some identifying marks. You could try decapping the chip or if you have access to it, x-ray inspection. Thats not going to help much if it is custom part or not sold on the open market. If it is is an off-the-shelf part with a custom marking or custom package, you might be able to figure that out. I wouldn't count on it, though.

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