Move master branch from from mios git repo

AVR/lib/spi/spi-test-masterslave.c

@@ -0,0 +1,88 @@
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <spi.h>
+
+#define FLASH_LED_COMMAND 0x01
+#define OTHER_SELECT_PIN PB6
+#define SELECT_OTHER PORTB &= ~(1<<OTHER_SELECT_PIN)
+#define DESELECT_OTHER PORTB |= (1<<OTHER_SELECT_PIN)
+
+#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)
+{
+  DDRD |= (1<<PD7);
+  for (int i=0; i<count*2; i++) {
+    PORTD ^= (1<<PD7);
+    _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 the button pushed and pin INT0 goes from 1 to 0
+ISR(INT0_vect)
+{
+  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;
+  }
+}
+ 
+int main(void)
+{
+  // make sure other device is unselected (pin is HIGH) and setup spi
+  DESELECT_OTHER;
+  DDRB |= (1<<OTHER_SELECT_PIN);
+  setup_spi(SPI_MODE_1, SPI_MSB, SPI_INTERRUPT, SPI_SLAVE);
+  
+  // raise interrupt when the button is pushed and INT0 pin goes 
+  // from 1 to 0 (pin PD0 at AT90usbXXX, pin PD2 on ATmegaXXX, 
+  // arduino pin 2)). The code in ISR(INT0_vect) above will be called
+  EICRB = (1<<ISC01) | (0<<ISC00);
+  EIMSK |= (1<<INT0);
+  sei();
+
+  // flash LED at start to indicate were ready
+  flash_led(1);
+
+  while (1); // do nothing
+}