new example, restored pics

examples/blinkmodes/blinkmodes.ino

@@ -0,0 +1,66 @@
+// This is an example sketch to demonstrate embedded debugging
+// It is a modified blink sketch. It has four different modes:
+// off, on, slow blinking, fast blinking. You can cycle through these
+// modes by pressing a button, which is read using an interrupt.
+// Parallel to that, we prcess an ASCII input stream inverting the case of each
+// character before sending it out.
+//
+// In order to keep external components
+// at minimum, we use the builtin LED and a single button.
+// The blinking is implemented by using the "Timer/Counter0 Compare Match A"
+// interrupt.
+
+#include <ctype.h>
+
+#define LEDPIN LED_BUILTIN
+#define BUTTON 2
+#define BUTTONGND 4
+
+byte counter = 0;                   // the counter for blinking, it counts ms
+byte mode = 0;                      // the mode of the b linker
+unsigned long lastpress = 0;        // when was button pressed last?
+
+const byte debounce_ms = 100;       // the debounce time in ms
+
+void setup() {
+  Serial.begin(19200);
+  Serial.println(F("\nblinkmode V1.0.0"));
+  pinMode(LEDPIN, OUTPUT);           // initialize LEDPIN 
+  pinMode(BUTTONGND, OUTPUT);        // make neighboring pin GND for the button
+  pinMode(BUTTON, OUTPUT);           // initialize button
+  TIMSK0 |= _BV(OCIE0A);             // enable Timer0 Compare Match A interrupt
+  OCR0A = 0x80;                      // set interrupt time between two millis interrupts
+  attachInterrupt(digitalPinToInterrupt(BUTTON), readButton, FALLING);
+}
+
+void loop() {
+  char c;
+
+  if (Serial.available()) {
+    c = Serial.read();
+    if (isupper(c)) Serial.print(tolower(c));
+    else Serial.println(toupper(c));
+
+  }
+}
+
+void readButton() {
+  if (lastpress + debounce_ms > millis())
+    return;
+  lastpress = millis();              // remember time of last press for debouncing
+  mode = (mode+1) % 4;               // go to next mode
+}
+
+ISR(TIMER0_COMPA_vect) {              // timer ISR
+  counter++;                          // advance counter
+  if (mode == 0)
+    digitalWrite(LEDPIN, 0);          // in mode 0, switch LED off
+  if (mode == 1)
+    digitalWrite(LEDPIN, 1);          // in mode 1, switch LED on
+  else if ((mode == 2 && counter > 500) || // in mode 2, toggle when going above 500
+	   (counter > 100)) {         // otherwise, when mode 3, after going above 100, 
+    digitalWrite(LEDPIN,              // toggle LEDPIN
+		   !digitalRead(LEDPIN));
+    counter = 0;                      // reset counter to zero
+  }   
+}