it work now thank you all for help @madmisha your idea of adding diodes what fix this problem thanks alot here is the final connection hope it wil...

I made a big mistake it was MISO not MOSI pin what i'm talking about srry about that

MOSI line work with PNP transistor or NPN

i found solution on some other form but i didn't now how to do it. it was said to add or gate on MOSI line to switch between the 2 rc522 but how...

here is the diagram

@will didn't work

I have question, dos different wires length matter because one of them longer than the other ?

@madmisha I tried it with no luck at all same problem i even use the example code without any edit but still same problem didn't work same connect...

@will 1) the is freely opens from inside however from outside you must use you tag, so there no problem there and the door auto look it self and if ...

@madmisha the code #include <SPI.h>#include <MFRC522.h>#define SS_DoorPIN 9#define SS_LightPIN 8#define RST_PIN 10//#define Light 3//#...

ahhh i get what you mean however the room will only be used by one person only so no problem in that and if this person forget his card in the room i ...

We have no safety rules or any thing like that in Egypt about building . About my project the main idea here is you must get your key out from y...

@will We don't have something like that here in Egypt :)

What you mean?!!