add untested Arduino Nano SPI driver

3 files changed, 51 insertions, 2 deletions

diff --git a/src/arch/arduino-nano/Makefile.inc b/src/arch/arduino-nano/Makefile.inc
index 9e149ac..ebc77ea 100644
--- a/src/arch/arduino-nano/Makefile.inc
+++ b/src/arch/arduino-nano/Makefile.inc
@@ -37,6 +37,10 @@ else ifneq ($(findstring i2c,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/i2c.cc
 endif
 
+ifneq ($(findstring spi,${arch_drivers}), )
+	CXX_TARGETS += src/arch/arduino-nano/driver/spi.cc
+endif
+
 ifneq ($(findstring stdin,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/stdin.cc
 endif
diff --git a/src/arch/arduino-nano/arch.cc b/src/arch/arduino-nano/arch.cc
index 221ef5b..1023927 100644
--- a/src/arch/arduino-nano/arch.cc
+++ b/src/arch/arduino-nano/arch.cc
@@ -105,12 +105,16 @@ void Arch::idle(void)
 
 void Arch::delay_us(unsigned int const us)
 {
-	_delay_us(us);
+	for (unsigned int i = 0; i < us; i++) {
+		_delay_us(1);
+	}
 }
 
 void Arch::delay_ms(unsigned int const ms)
 {
-	_delay_ms(ms);
+	for (unsigned int i = 0; i < ms; i++) {
+		_delay_ms(1);
+	}
 }
 
 Arch arch;
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;