Add libraries, picocalc notes.

libraries/arduino_picocalc_kbd/examples/GPIOExpander/GPIOExpander.ino

@@ -0,0 +1,31 @@
+#include <PCKeyboard.h>
+
+#define CARD_DET 1
+
+PCKeyboard keyboard;
+int prevValue = LOW;
+
+void setup()
+{
+  Serial.begin(9600);
+
+  Wire.setSDA(4);
+  Wire.setSCL(5);
+  Wire.begin();
+  Wire.setClock(10000);
+
+  keyboard.begin();
+  keyboard.pinMode(CARD_DET, INPUT);
+  keyboard.digitalWrite(CARD_DET, HIGH); // Enable pull-up
+}
+
+void loop()
+{
+  const int value = keyboard.digitalRead(CARD_DET);
+  if (value == prevValue)
+    return;
+
+  Serial.printf("Card Detect: %d \r\n", value);
+
+  prevValue = value;
+}

libraries/arduino_picocalc_kbd/examples/InterruptDriven/InterruptDriven.ino

@@ -0,0 +1,51 @@
+#include <PCKeyboard.h>
+
+PCKeyboard keyboard;
+volatile bool dataReady = false;
+
+const int interruptPin = 5;
+
+void KeyIsr(void)
+{
+  dataReady = true;
+}
+
+void setup()
+{
+  Serial.begin(9600);
+  Wire.setSDA(4);
+  Wire.setSCL(5);
+  Wire.begin();
+  Wire.setClock(10000);
+
+  keyboard.begin();
+  keyboard.attachInterrupt(interruptPin, KeyIsr);
+  keyboard.setBacklight(0.5f);
+}
+
+void loop()
+{
+  if (!dataReady)
+    return;
+
+  const PCKeyboard::KeyEvent key = keyboard.keyEvent();
+  String state = "pressed";
+  if (key.state == PCKeyboard::StateLongPress)
+    state = "held down";
+  else if (key.state == PCKeyboard::StateRelease)
+    state = "released";
+
+  Serial.printf("key: '%c' (dec %d, hex %02x) %s\r\n", key.key, key.key, key.key, state.c_str());
+
+  // pressing 'b' turns off the backlight and pressing Shift+b turns it on
+  if (key.state == PCKeyboard::StatePress) {
+    if (key.key == 'b') {
+      keyboard.setBacklight(0);
+    } else if (key.key == 'B') {
+      keyboard.setBacklight(1.0);
+    }
+  }
+
+  keyboard.clearInterruptStatus();
+  dataReady = false;
+}

libraries/arduino_picocalc_kbd/examples/Polling/Polling.ino

@@ -0,0 +1,41 @@
+#include <PCKeyboard.h>
+
+PCKeyboard keyboard;
+
+void setup()
+{
+  Serial.begin(9600);
+  
+  Wire.setSDA(4);
+  Wire.setSCL(5);
+  Wire.begin();
+  Wire.setClock(10000);
+
+  keyboard.begin();
+  keyboard.setBacklight(0.5f);
+}
+
+void loop()
+{
+  const int keyCount = keyboard.keyCount();
+  if (keyCount == 0)
+    return;
+
+  const PCKeyboard::KeyEvent key = keyboard.keyEvent();
+  String state = "pressed";
+  if (key.state == PCKeyboard::StateLongPress)
+    state = "held down";
+  else if (key.state == PCKeyboard::StateRelease)
+    state = "released";
+  
+  Serial.printf("key: '%c' (dec %d, hex %02x) %s\r\n", key.key, key.key, key.key, state.c_str());
+
+  // pressing 'b' turns off the backlight and pressing Shift+b turns it on
+  if (key.state == PCKeyboard::StatePress) {
+    if (key.key == 'b') {
+      keyboard.setBacklight(0);
+    } else if (key.key == 'B') {
+      keyboard.setBacklight(1.0);
+    }
+  }
+}