Move master branch from from mios git repo

AVR/lib/spi/Arduino/SPI/examples/MasterSlave/MasterSlave.pde

@@ -0,0 +1,91 @@
+#include <spi.h>
+#include <util/delay.h>
+
+#define BUTTON_PIN 2
+#define LED_PIN 3
+#define FLASH_LED_COMMAND 0x01
+
+#define OTHER_SELECT_PIN 7
+#define SELECT_OTHER digitalWrite(OTHER_SELECT_PIN, LOW);
+#define DESELECT_OTHER digitalWrite(OTHER_SELECT_PIN, HIGH);
+
+#define BUFSIZE 20
+volatile unsigned char incoming[BUFSIZE];
+volatile short int received=0;
+
+// flash led that's connected to pin PD7
+void flash_led(int count)
+{
+  pinMode(LED_PIN, OUTPUT);
+  for (int i=0; i<count*2; i++) {
+    digitalWrite(LED_PIN, i%2==0);
+    _delay_ms(75);
+  }
+}
+
+// send a SPI message to the other device - 3 bytes then go back into 
+// slave mode
+void send_message()
+{
+  setup_spi(SPI_MODE_1, SPI_MSB, SPI_NO_INTERRUPT, SPI_MSTR_CLK8);
+  if (SPCR & (1<<MSTR)) { // if we are still in master mode
+    SELECT_OTHER; // tell other device to flash LED twice
+    send_spi(FLASH_LED_COMMAND); send_spi(0x02); send_spi(0x00);
+    DESELECT_OTHER;
+  }
+  setup_spi(SPI_MODE_1, SPI_MSB, SPI_INTERRUPT, SPI_SLAVE);
+}
+
+
+// called when button pushed and pin INT0 goes from 1 to 0
+void button_pressed()
+{
+  send_message();
+  _delay_ms(500);  // 'debounce'
+}
+
+// parse the data received from the other device
+// currently just knows about the FLASH_LED_COMMAND
+void parse_message()
+{
+  switch(incoming[0]) {
+  case FLASH_LED_COMMAND:
+    flash_led(incoming[1]);
+    break;
+  default:
+    flash_led(20);
+  }
+}
+
+// called by the SPI system when there is data ready.
+// Just store the incoming data in a buffer, when we receive a
+// terminating byte (0x00) call parse_message to process the data received
+ISR(SPI_STC_vect)
+{
+  incoming[received++] = received_from_spi(0x00);
+  if (received == BUFSIZE || incoming[received-1] == 0x00) {
+      parse_message();
+      received = 0;
+   }
+}
+
+void setup()
+{
+  // make sure other device is unselected (pin is HIGH) and setup spi
+  DESELECT_OTHER;
+  pinMode(OTHER_SELECT_PIN, OUTPUT);
+  setup_spi(SPI_MODE_1, SPI_MSB, SPI_INTERRUPT, SPI_SLAVE);
+
+  // raise interrupt when INT0 pin falls (arduino pin 2))
+  // the function button_pressed will be called
+  attachInterrupt(0, button_pressed, FALLING);
+
+  // flash LED at start to indicate were ready
+  flash_led(1);
+}
+
+
+void loop()
+{
+  // do nothing
+}