It's used only as a dev dependency in 2 crates.

Number of dependers MFRC522 version Downloads/month
0 0.7.0 40
1 0.3.1 11
1 0.2.0 32
Depender (with downloads and own rev deps) MFRC522 version
2.9K 32 stm32f1xx-hal dev ^0.3.0
2 stm32f1xx-hal-bxcan dev ^0.2.0