Problem: RFID with Arduino Mega 2560

i'm working on project includes reading rfid. i'm using arduino mega 2560 along yhy502 rfid reader , mifare 4k tags.

i'm not able read card serial number. when card there, appears on serial monitor -1 means tag not available.

note in datasheet of rfid module (http://www.webtronico.com/documentos/ds_yhy502ctg.pdf), header byte should aa. again, i'm getting ff when card not available.


please, need issue. 

if read sticky thread "how use forum" you'll find instructions on how post code. need see code in order help.

it idea post clear picture of wiring.

a link 4k mifare tags you're using idea. (i've used 1k tags/cards myself.)

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