Correction its PA0 (port22) - Sorry
:o
Here is what I did:
The sketch DATA_PIN actually refers to the AVR pin not the arduino pin. PortE-H can NOT be used, so I chose PORTA. In this instance PA0 (PORT A 0) which correlates to pin 22 on the arduino 2560.
#define DATA_PORT PORTA
#define DATA_DDR DDRA
I also had to change ISR (USART_RX_vect) to ISR (USART0_RX_vect )
and volatile unsigned char go = 0; to boolean go = 0;
I successfully tested this code with 900 led's on the 2560.
That's it, enjoy!
Regards!