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Ah, your hotel card might contain non ASCII characters, say Unicoded Chinese. So you need to decode the Unicoded Chinese characters each of which is denoted by two bytes. Of course hotel cards usually use other tricks to punish the bad guys trying to clone.


Either of those should work (obviously assuming you select the appropriate pins on the device. Frankly I wouldn't do it this way. A typical use of a Level Shifter is shown directly wired to a device. The Pi is on the Right, the Red wire is 5V to HV; the Black Gnd (both soldered to the same pads) Pink is 3.3V to LV, Grey GPIO. This is only unidirectional ...

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