Started following some tutorial on att85 usi. Downloaded example code from make avr book.

Make AVR Examples/Chapter05_Serial-IO/serialOrgan/organ.c

@@ -0,0 +1,26 @@
+/*
+Simple routines to play notes out to a speaker
+*/
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include "organ.h"
+#include "pinDefines.h"
+
+void playNote(uint16_t period, uint16_t duration) {
+  uint16_t elapsed;
+  uint16_t i;
+  for (elapsed = 0; elapsed < duration; elapsed += period) {
+                     /* For loop with variable delay selects the pitch */
+    for (i = 0; i < period; i++) {
+      _delay_us(1);
+    }
+    SPEAKER_PORT ^= (1 << SPEAKER);
+  }
+}
+
+void rest(uint16_t duration) {
+  do {
+    _delay_us(1);
+  } while (--duration);
+}