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I've got an e-paper price tag from a friend of mine and I'd like to know if it's possible to change the display contents? On the back it says its a Solu M from 2017, model number ST-GM29MT1. I haven't found much information about it online, and I couldn't get it apart (without excessive force). I've seen there are transmitters on the website that sells these, but all it says is that it's a 2.4 GHz protocol. Maybe it's just something like zigbee? Also, they don't specify prices so it's probably really expensive.

Is there a way I can modify the text, preferrably without the expensive original hardware? What would be a good place to start trying?

Edit: According to this datasheet of a similar product from this manufacturer it seems it is indeed ZigBee.

Edit2: Found the exact device and it really seems to be ZigBee, but how could i test that?

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    \$\begingroup\$ The protocol is specified as proprietary. I have doubts that you'll find anyone skilled and dedicated enough to help you reverse engineer this protocol. Considered that it's very niche. \$\endgroup\$
    – Velvet
    Mar 4, 2022 at 22:19
  • \$\begingroup\$ If you can get the generic protocol then you can try that on the branded model. Other than that, fcc.io if there is a fcc oid number, and look at YouTube for some guy that hacks them, generally speaking. Sometimes you can't figure out the wireless protocol so the next step is replacing the controller. The display sometimes has its own driver instead of it being an all in one design. \$\endgroup\$
    – Passerby
    Mar 4, 2022 at 22:25
  • \$\begingroup\$ @Passerby From what I can tell on the photos on the FCC sheets, the controller is separate from the display, and I would have just made my own controller board (since I don't intend to go around grocery stores changing pricetags with my "hacked" protocol, although I suspect it would be quite funny) but I cannot for the life of me get this thing apart... I see some ISP(?) pads on the back, maybe I can just reprogram the controller...? \$\endgroup\$
    – Twometer
    Mar 5, 2022 at 0:29
  • \$\begingroup\$ Unfortunately, the schematics of the thing on the FCC website are not public. \$\endgroup\$
    – Twometer
    Mar 5, 2022 at 0:30
  • \$\begingroup\$ You could reprogram the controller, if it's not locked, and those pads are for the bare microcontroller and not a custom programming protocol for the firmware already installed. And you have a way of programming that specific microcontroller family. Then you still have issues with programming the display and wireless interface controllers from scratch. \$\endgroup\$
    – Passerby
    Mar 5, 2022 at 0:40

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