add (untested!) MSP430 SPI driver

include/msp430fr5969lp/driver/spi.h

+#ifndef SPI_H
+#define SPI_H
+
+class SPI {
+	private:
+		SPI(const SPI &copy);
+
+	public:
+		SPI () {}
+		signed char setup();
+		signed char xmit(
+				unsigned char tx_len, unsigned char *tx_buf,
+				unsigned char rx_len, unsigned char *rx_buf);
+};
+
+extern SPI spi;
+
+#endif

include/msp430fr5969lp/driver/spi_b.h

+#ifndef SPI_H
+#define SPI_H
+
+class SPI {
+	private:
+		SPI(const SPI &copy);
+
+	public:
+		SPI () {}
+		signed char setup();
+		signed char xmit(
+				unsigned char tx_len, unsigned char *tx_buf,
+				unsigned char rx_len, unsigned char *rx_buf);
+};
+
+extern SPI spi;
+
+#endif

src/arch/msp430fr5969lp/driver/spi.cc

+#include "driver/spi.h"
+#include <msp430.h>
+
+signed char SPI::setup()
+{
+	/* UCA1CLK Pin 2.4 */
+	P2SEL0 &= ~BIT4;
+	P2SEL1 |= BIT4;
+	P2DIR |= BIT4;
+
+	/* UCA1SIMO Pin 2.5 */
+	P2SEL0 &= ~BIT5;
+	P2SEL1 |= BIT5;
+	P2DIR |= BIT5;
+
+	/* UCA1SOMI Pin 2.6 */
+	P2SEL0 &= ~BIT6;
+	P2SEL1 |= BIT6;
+	P2DIR &= ~BIT6;
+	//P2REN |= BIT6;
+
+	UCA1CTLW0 |= UCSWRST;
+	UCA1MCTLW = 0; // no modulation
+
+	UCA1CTLW0 = UCCKPH | UCMSB | UCMST | UCSYNC | UCMODE_0 | UCSSEL__SMCLK | UCSWRST;
+	UCA1BRW = 15; // /16 -> 1MHz
+	UCA1CTLW0 &= ~UCSWRST;
+}
+
+signed char SPI::xmit(unsigned char tx_len, unsigned char *tx_buf,
+		unsigned char rx_len, unsigned char *rx_buf)
+{
+	volatile char rxbuf_cache;
+	if (tx_len < 1) {
+		return -1;
+	}
+
+	UCA1IE &= ~(UCTXIE | UCRXIE);
+
+	while (UCA1STATW & UCBUSY) ;
+
+	rxbuf_cache = UCA1RXBUF;
+	UCA1TXBUF = tx_buf[0];
+
+	unsigned char tx_pos = 1;
+	unsigned char rx_pos = 0;
+
+	while (tx_pos < tx_len || rx_pos < rx_len) {
+		if ((tx_pos < tx_len) && (UCA1IF & UCTXIFG)) {
+			UCBA1TXBUF = tx_buf[tx_pos++];
+		}
+		if (UCA1IFG & UCRXIFG) {
+			if (rx_pos < rx_len) {
+				rx_buf[rx_pos] = UCA1RXBUF;
+			} else {
+				rxbuf_cache = UCA1RXBUF;
+			}
+		}
+		rx_pos++;
+	}
+}

src/arch/msp430fr5969lp/driver/spi_b.cc

+#include "driver/spi.h"
+#include <msp430.h>
+
+signed char SPI::setup()
+{
+	/* UCB0CLK Pin 2.2 */
+	P2SEL0 &= ~BIT2;
+	P2SEL1 |= BIT2;
+	P2DIR |= BIT2;
+
+	/* UCB0SIMO Pin 1.6 */
+	P1SEL0 &= ~BIT6;
+	P1SEL1 |= BIT6;
+	P1DIR |= BIT6;
+
+	/* UCB0SOMI Pin 1.7 */
+	P1SEL0 &= ~BIT7;
+	P1SEL1 |= BIT7;
+	P1DIR &= ~BIT7;
+	//P1REN |= BIT6;
+
+	UCB0CTLW0 = UCCKPH | UCMSB | UCMST | UCSYNC | UCMODE_0 | UCSSEL__SMCLK | UCSWRST;
+	UCB0BRW = 15; // /16 -> 1MHz
+	UCB0CTLW0 &= ~UCSWRST;
+}
+
+signed char SPI::xmit(unsigned char tx_len, unsigned char *tx_buf,
+		unsigned char rx_len, unsigned char *rx_buf)
+{
+	volatile char rxbuf_cache;
+	if (tx_len < 1) {
+		return -1;
+	}
+
+	UCB0IE &= ~(UCTXIE | UCRXIE);
+
+	while (UCB0STATW & UCBUSY) ;
+
+	rxbuf_cache = UCB0RXBUF;
+	UCB0TXBUF = tx_buf[0];
+
+	unsigned char tx_pos = 1;
+	unsigned char rx_pos = 0;
+
+	while (tx_pos < tx_len || rx_pos < rx_len) {
+		if ((tx_pos < tx_len) && (UCB0IFG & UCTXIFG)) {
+			UCB0TXBUF = tx_buf[tx_pos++];
+		}
+		if (UCB0IFG & UCRXIFG) {
+			if (rx_pos < rx_len) {
+				rx_buf[rx_pos] = UCB0RXBUF;
+			} else {
+				rxbuf_cache = UCB0RXBUF;
+			}
+			rx_pos++;
+		}
+	}
+}