Carpark entry counter

Using Arduino Programming Questions
5

Assuming you're using an SPI-based Ethernet shileld...

Arduino communicates with both the W5100 and SD card using the SPI bus (through the ICSP header). This is on digital pins 11, 12, and 13 on the Duemilanove Uno.

const int CounterChange =  13;      // the number of the LED pin