MicroSD cards connect to microcontrollers over SPI or SDIO
Mbsmpro.com, MicroSD Interface, SPI Wiring, CS MOSI MISO SCK, 3.3V Level Shifter, Pinout, Data Logging

Mbsmpro.com, MicroSD Interface, SPI Wiring, CS MOSI MISO SCK, 3.3V Level Shifter, Pinout, Data Logging