mfrc522 library port for CodeVisionAVR
descriptions are in the library
miso : input, pull up
mosi : output, 0V
sck : output, 0V
sda : set in the library (cs_clr,cs_set)
spi mode : mode 0
clock phase : cycle start
clock polarity : low
spi type : master
data order : MSB first
clock rate : 500 kHz