#ifdef ENC28J60_USART_SPI_MODE 
uint8_t enc28j60ReadOp(uint8_t op, uint8_t address) {
	CSACTIVE;
	/* Wait for empty transmit buffer */
	while ( !( UCSR0A & (1<<UDRE0)) );
	// issue read command
	UDR0 = op | (address & ADDR_MASK);
	waitspi();
	// read data
	UDR0 = 0x00;
	waitspi();
	// do dummy read if needed (for mac and mii, see datasheet page 29)
	if(address & 0x80) {
		UDR0 = 0x00;
		waitspi();
	}	
	// release CS
	CSPASSIVE;
	return UDR0;
}

void enc28j60WriteOp(uint8_t op, uint8_t address, uint8_t data) {
	CSACTIVE;
	/* Wait for empty transmit buffer */
	while ( !( UCSR0A & (1<<UDRE0)) );
	// issue write command
	UDR0 = op | (address & ADDR_MASK);
	waitspi();
	// write data
	UDR0 = data;
	waitspi();
	CSPASSIVE;
}

void enc28j60ReadBuffer(uint16_t len, uint8_t* data) {
	CSACTIVE;
	/* Wait for empty transmit buffer */
	while ( !( UCSR0A & (1<<UDRE0)) );
	// issue read command
	UDR0 = ENC28J60_READ_BUF_MEM;
	waitspi();
	while(len) {
		len--;
		// read data
		UDR0 = 0x00;
		waitspi();
		*data = UDR0;
		data++;
	}
	*data='\0';
	CSPASSIVE;
}

void enc28j60WriteBuffer(uint16_t len, uint8_t* data) {
	CSACTIVE;
	/* Wait for empty transmit buffer */
	while ( !( UCSR0A & (1<<UDRE0)) );
	// issue write command
	UDR0 = ENC28J60_WRITE_BUF_MEM;
	waitspi();
	while(len) {
		len--;
		// write data
		UDR0 = *data;
		data++;
		waitspi();
	}
	CSPASSIVE;
}

#else
uint8_t enc28j60ReadOp(uint8_t op, uint8_t address) {
	CSACTIVE;
	// issue read command
	SPDR = op | (address & ADDR_MASK);
	waitspi();
	// read data
	SPDR = 0x00;
	waitspi();
	// do dummy read if needed (for mac and mii, see datasheet page 29)
	if(address & 0x80) {
		SPDR = 0x00;
		waitspi();
	}
	// release CS
	CSPASSIVE;
	return(SPDR);
}

void enc28j60WriteOp(uint8_t op, uint8_t address, uint8_t data) {
	CSACTIVE;
	// issue write command
	SPDR = op | (address & ADDR_MASK);
	waitspi();
	// write data
	SPDR = data;
	waitspi();
	CSPASSIVE;
}

void enc28j60ReadBuffer(uint16_t len, uint8_t* data) {
	CSACTIVE;
	// issue read command
	SPDR = ENC28J60_READ_BUF_MEM;
	waitspi();
	while(len) {
		len--;
		// read data
		SPDR = 0x00;
		waitspi();
		*data = SPDR;
		data++;
	}
	*data='\0';
	CSPASSIVE;
}

void enc28j60WriteBuffer(uint16_t len, uint8_t* data) {
	CSACTIVE;
	// issue write command
	SPDR = ENC28J60_WRITE_BUF_MEM;
	waitspi();
	while(len) {
		len--;
		// write data
		SPDR = *data;
		data++;
		waitspi();
	}
	CSPASSIVE;
}
#endif