Add some simple AVR sketches

led1.c

@@ -0,0 +1,18 @@
+#include <avr/io.h>
+#include <util/delay.h>
+#include <limits.h>
+
+int main(void) {
+    int i;
+
+    DDRB = 0xff;
+
+    PORTB = 0b10101010;
+
+    for (;;) {
+        PORTB = PORTB ^ 0xff;
+        _delay_ms(1000);
+    }
+
+    return 0;
+}

led2.c

@@ -0,0 +1,27 @@
+#include <avr/io.h>
+#include <util/delay.h>
+#include <limits.h>
+
+#define DELAY 50
+#define BITS sizeof(PORTB) * CHAR_BIT - 1
+
+int main(void) {
+    int i;
+
+    DDRB = 0xff;
+
+    PORTB = 1;
+
+    for (;;) {
+        for (i = 0; i < BITS; i++) {
+            _delay_ms(DELAY);
+            PORTB = PORTB << 1;
+        }
+        for (i = BITS; i > 0; i--) {
+            _delay_ms(DELAY);
+            PORTB = PORTB >> 1;
+        }
+    }
+
+    return 0;
+}