chore(examples): enhance button support

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

examples/Central/LedControl/LedControl.ino

@@ -17,19 +17,28 @@
 #include <STM32duinoBLE.h>
 
 // variables for button
-const int buttonPin = 2;
+#ifdef USER_BTN
+const int buttonPin = USER_BTN; // set buttonPin to on-board button
+#else
+const int buttonPin = PC13; // set buttonPin to digital pin PC13 */
+#endif
 int oldButtonState = LOW;
+int initialButtonState = LOW;
 
 void setup() {
   Serial.begin(9600);
   while (!Serial);
 
   // configure the button pin as input
-  pinMode(buttonPin, INPUT);
+  pinMode(buttonPin, INPUT_PULLUP);
 
   // initialize the Bluetooth® Low Energy hardware
   BLE.begin();
 
+  // Get initial button state
+  initialButtonState = digitalRead(buttonPin);
+  oldButtonState = initialButtonState;
+
   Serial.println("Bluetooth® Low Energy Central - LED control");
 
   // start scanning for peripherals
@@ -108,7 +117,7 @@ void controlLed(BLEDevice peripheral) {
       // button changed
       oldButtonState = buttonState;
 
-      if (buttonState) {
+      if (buttonState != initialButtonState) {
         Serial.println("button pressed");
 
         // button is pressed, write 0x01 to turn the LED on

examples/Peripheral/ButtonLED/ButtonLED.ino

@@ -18,7 +18,11 @@
 #include <STM32duinoBLE.h>
 
 const int ledPin = LED_BUILTIN; // set ledPin to on-board LED
-const int buttonPin = 4; // set buttonPin to digital pin 4
+#ifdef USER_BTN
+const int buttonPin = USER_BTN; // set buttonPin to on-board button
+#else
+const int buttonPin = PC13; // set buttonPin to digital pin PC13 */
+#endif
 
 BLEService ledService("19B10010-E8F2-537E-4F6C-D104768A1214"); // create service
 
@@ -32,7 +36,7 @@ void setup() {
   while (!Serial);
 
   pinMode(ledPin, OUTPUT); // use the LED as an output
-  pinMode(buttonPin, INPUT); // use button pin as an input
+  pinMode(buttonPin, INPUT_PULLUP); // use button pin as an input
 
   // begin initialization
   if (!BLE.begin()) {