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| 2-pads printer ink chip? |
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| bitwelder:
I was recently replacing the toner cartridge of my Oki laser printer. Looking at the 'smart' ink chip on it, it's a 6-pins SMD chip (SOIC-6 perhaps?) with only 2 pins connected to external pads on the tiny PCB. With only 2 terminals, how does in general such a chip work? Is the exchanged data encoded in the supply voltage, or does it communicate in some other way, e.g. a Hall (or other magnetic field) sensor? |
| ebastler:
One solution is commercially available as "1-Wire", by Dallas Semiconductor. https://en.wikipedia.org/wiki/1-Wire It charges a capacitor to buffer the supply voltage while serial data communications are underway. |
| daqq:
There are a few standards that allow communication and power over a single wire + GND. 1 Wire or the Microchip standard: http://ww1.microchip.com/downloads/en/DeviceDoc/AT21CS01-AT21CS11-Data-Sheet-DS20005857D.pdf There are actually crypto authentication devices that enable single wire communication, can't remember which devices, designed precisely for this situation. |
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