i am very new to hardware circuitry and am attempting to connect a wiegand rfid and pin code reader to a raspberry pi for door access control logic. more details at: https://gist.github.com/grenade/d7289df5c83172b82052b2b87df9f978.
in the 2nd photo below, there are 3 wires connected to a bidirectional level shifter (5v - 3.3v). from left to right they are connected as follows:
- wiegand data 0 - level shifter hv 1
- wiegand gnd - level shifter hv gnd
- wiegand data 1 - level shifter hv 4
i intend to connect the level shifter to the raspberry pi as follows:
- raspi gpio 04 - level shifter hv
- raspi gpio 06 - level shifter lv gnd
- raspi gpio 11 - level shifter lv 1 (lower left pin)
- raspi gpio 12 - level shifter lv 4 (lower right pin)
- raspi gpio 17 - level shifter lv
i am following a related post which describes a schematic which uses similar hardware.
- multimeter shows 12v coming from the power supply at the top of the first picture
- multimeter shows 6v coming from both data 0 and data 1 on the wiegand reader. i was expecting 5.5v, but whatever.
- multimeter shows 6v coming from both lv 1 and lv 4 on the level shifter. i was expecting a level shift down to 3v ~ 4v.
have i misunderstood what level shifters do or is this one a dud since it outputs the same voltage on the lv end as is going in on the hv end?