[sam] fixed SPI initialization

Fixes #1561

Author: cmaglie

build/shared/revisions.txt

@@ -1,4 +1,9 @@
 
+ARDUINO 1.5.4 BETA
+
+[libraries]
+* sam: fixed wrong SPI initialization (noblepepper)
+
 ARDUINO 1.5.3 BETA 2013.08.30
 
 [ide]

libraries/SPI/arch/sam/SPI.cpp

@@ -30,6 +30,10 @@ void SPIClass::begin() {
 }
 
 void SPIClass::begin(uint8_t _pin) {
+	initCb();
+	SPI_Configure(spi, id, SPI_MR_MSTR | SPI_MR_PS | SPI_MR_MODFDIS);
+	SPI_Enable(spi);
+
 	uint32_t spiPin = BOARD_PIN_TO_SPI_PIN(_pin);
 	PIO_Configure(
 		g_APinDescription[spiPin].pPort,