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Comment by dperfect | Hacker News Reader

Nicely done! Instead of a device to rewind/reset the counter in the EEPROM periodically, I wonder how hard it would be to modify or replace the EEPROM with something that simply ignores any modification to the data (essentially making it read-only). That way, the machine thinks it's decrementing the counter each time, but it always remains full. There'd be no need for a software reset.

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I think because you still want the counter so you know when to refill the cartridge. You’re not really benefiting by having it always show full.

I wonder how well it would work if someone bypassed the cartridge and just hooked the dishwasher directly to the two giant external jugs, like one of those external CMYK ink tank systems for fancy printers.

That's true. I suppose keeping track another way might offset the added annoyance of the "rewind" routine (attaching another device, connecting USB for power) when refilling the reservoirs. Personal preference I guess.

Replace PCB with your own one having MCU with buit-in EEPROM. Add a tiny push button (or just two copper pads), pressing/closing which will dischage a capacitor indicating "need to rewind" to an MCU. When counter is zero, you take off the cartridge, pour in all necessary chemicals, hold the button for a while and put it back into the machine.

In the ink cartridge industry those are known as "autoreset chips", and they do count down, but reset once removed from the printer (and presumably because that means you have noticed and now refilled the cartridge.)

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