Convert time related functions to std::chrono

To get rid of deprecation warnings

Author: facchinm

cores/arduino/Tone.cpp

@@ -1,6 +1,9 @@
 #include "Arduino.h"
 #include "mbed.h"
 
+using namespace std::chrono_literals;
+using namespace std::chrono;
+
 class Tone {
     mbed::DigitalOut   *pin;
     mbed::Timer        timer;
@@ -21,7 +24,7 @@ class Tone {
     }
 
     void start(void) {
-        ticker.attach(mbed::callback(this, &Tone::toggle), 0.5f / float(frequency));
+        ticker.attach(mbed::callback(this, &Tone::toggle), 500ms / frequency );
         if (duration != 0) {
             start_timeout();
         }
@@ -37,7 +40,7 @@ class Tone {
     }
 
     void start_timeout(void) {
-        timeout.attach(mbed::callback(this, &Tone::stop), duration/1000.0f);
+        timeout.attach(mbed::callback(this, &Tone::stop), duration * 1ms);
     }
 };
 

cores/arduino/wiring.cpp

@@ -32,19 +32,22 @@ static mbed::LowPowerTimer t;
 static mbed::Timer t;
 #endif
 
+using namespace std::chrono_literals;
+using namespace std::chrono;
+
 unsigned long millis()
 {
-  return t.read_ms();
+  return duration_cast<milliseconds>(t.elapsed_time()).count();
 }
 
 unsigned long micros() {
-  return t.read_us();
+  return t.elapsed_time().count();
 }
 
 void delay(unsigned long ms)
 {
 #ifndef NO_RTOS
-  rtos::ThisThread::sleep_for(ms);
+  rtos::ThisThread::sleep_for(ms * 1ms);
 #else
   wait_us(ms * 1000);
 #endif