add untested Arduino Nano SPI driver

1 files changed, 41 insertions, 0 deletions

diff --git a/src/arch/arduino-nano/driver/spi.cc b/src/arch/arduino-nano/driver/spi.cc
new file mode 100644
index 0000000..86aa311
--- /dev/null
+++ b/src/arch/arduino-nano/driver/spi.cc
@@ -0,0 +1,41 @@
+#include "driver/spi.h"
+#include "driver/gpio.h"
+#include "arch.h"
+#include <avr/io.h>
+
+signed char SPI::setup()
+{
+	// configure SS as output to avoid unintened switches to slave mode
+	gpio.output(GPIO::pb2, 0);
+	// up to 1 MHz SPI clock
+#if F_CPU == 16000000UL
+	SPCR = _BV(SPE) | _BV(MSTR) | _BV(SPR0);
+#elif F_CPU == 8000000UL
+	SPCR = _BV(SPE) | _BV(MSTR) | _BV(SPR0);
+#else
+	SPCR = _BV(SPE) | _BV(MSTR);
+#endif
+}
+
+signed char SPI::xmit(
+		unsigned char tx_len, unsigned char *tx_buf,
+		unsigned char rx_len, unsigned char *rx_buf)
+{
+	unsigned char i;
+
+	while ((i < tx_len) || (i < rx_len)) {
+		if (i < tx_len) {
+			SPDR = tx_buf[i];
+		} else {
+			SPDR = 0;
+		}
+		while (!(SPSR & _BV(SPIF))) ;
+		if (i < rx_len) {
+			rx_buf[i] = SPDR;
+		}
+		i++;
+	}
+	return 0;
+}
+
+SPI spi;