diff --git a/lib/matejx_avr_lib/hwdefs.h b/lib/matejx_avr_lib/hwdefs.h
new file mode 100644
index 0000000..691753e
--- /dev/null
+++ b/lib/matejx_avr_lib/hwdefs.h
@@ -0,0 +1,20 @@
+#ifndef MAT_HWDEFS_H
+#define MAT_HWDEFS_H
+
+#define DDR(x) (*(&x - 1))
+#define PIN(x) (*(&x - 2))
+
+#define MFRC522_SS_PORT     PORTB
+#define MFRC522_SS_BIT      0
+
+#define MFRC522_RST_PORT    PORTL
+#define MFRC522_RST_BIT     0
+
+#define SCK_DDR     DDRB
+#define SCK_BIT     DDB1
+#define MOSI_DDR    DDRB
+#define MOSI_BIT    DDB2
+#define MISO_DDR    DDRB
+#define MISO_BIT    DDB3
+
+#endif
\ No newline at end of file