SPI 5v and 3.3v together

:( Hi Everyone,I am using a RFID module 3.3v and MicroSD module 5v(the latter have a 3.3v regulator, resistors, and a little integrated on your plate), both communicated via SPI in a Arduino Uno board, the problem is MicroSD works but not RFID, if I disconnect the MicroSD whether RFID works, I would like to help me so I can use the two modules together

Do you have a 5V arduino board ? I think the microSD module has a level shifter to adapt the 3.3V for the microSD to the 5V signals of the Arduino. You need a level shifter for the RFID as well.

Peter_n: Do you have a 5V arduino board ? I think the microSD module has a level shifter to adapt the 3.3V for the microSD to the 5V signals of the Arduino. You need a level shifter for the RFID as well.

Thanks, I Have the RFID-RC522 module and CATALEX MicroSD card adapter V1.0 but I thought about removing the regulator 3.3v having MicroSD module and connect directly 3.3v , I'll be talking nonsense lol or could work ?

The microSD should operate on 3.3V, regardless where that 3.3V comes from. I think others connect the 5V SPI signals to the RC522 chip. I don't know if that is okay. Can you connect the RFID-RC522 to the I2C bus ? That way it won't interfere with the microSD at the SPI bus.

Peter_n:
The microSD should operate on 3.3V, regardless where that 3.3V comes from.
I think others connect the 5V SPI signals to the RC522 chip. I don’t know if that is okay. Can you connect the RFID-RC522 to the I2C bus ? That way it won’t interfere with the microSD at the SPI bus.

you’re right , it always works to 3.3v , RC522 does not have I2C, works only with 3.3V

JoeFlowLA: you're right , it always works to 3.3v , RC522 does not have I2C, works only with 3.3V

the only way that works is using MicroSD an ethernet shield , but I just need the module MicroSD