There is a small error in readme. In the table under "Connecting a Memory Card to Arduino" it is suggested that Command pin should be connected to D52 for Arduino Mega 2560.
In fact, it should be connected to D51. I have noticed that Memcarduino is not working out of the box on Mega and started to look for differences between the UNO and Mega Pinout. In UNO, command is connected to D11, which is a MOSI pin for SPI communication. On Mega, D51 is a MOSI pin. I switched it to D51 and everything works like a charm. :)
There is a small error in readme. In the table under "Connecting a Memory Card to Arduino" it is suggested that Command pin should be connected to D52 for Arduino Mega 2560.
In fact, it should be connected to D51. I have noticed that Memcarduino is not working out of the box on Mega and started to look for differences between the UNO and Mega Pinout. In UNO, command is connected to D11, which is a MOSI pin for SPI communication. On Mega, D51 is a MOSI pin. I switched it to D51 and everything works like a charm. :)