Initial v1.2.1 for Portenta_H7

### Initial Releases v1.2.1

1. Initial coding to support **Portenta_H7 boards** such as Portenta_H7 Rev2 ABX00042, etc., using [**ArduinoCore-mbed mbed_portenta** core](https://github.com/arduino/ArduinoCore-mbed)
2. Permit up to 16 super-long-time, super-accurate ISR-based timers to avoid being blocked
3. Using cpp code besides Impl.h code to use if Multiple-Definition linker error.
4. Bump version to v1.2.1 to sync with [STM32_TimerInterrupt library](https://github.com/khoih-prog/STM32_TimerInterrupt)

Author: khoih-prog

src/Portenta_H7_ISR_Timer.h

@@ -31,10 +31,8 @@
 #ifndef ISR_TIMER_GENERIC_H
 #define ISR_TIMER_GENERIC_H
 
-#if !( defined(STM32F0) || defined(STM32F1) || defined(STM32F2) || defined(STM32F3)  ||defined(STM32F4) || defined(STM32F7) || \
-       defined(STM32L0) || defined(STM32L1) || defined(STM32L4) || defined(STM32H7)  ||defined(STM32G0) || defined(STM32G4) || \
-       defined(STM32WB) || defined(STM32MP1) || defined(STM32L5))
-  //#error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting.
+#if !( ( defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4) ) && defined(ARDUINO_ARCH_MBED) )
+  #error This code is intended to run on the MBED ARDUINO_PORTENTA_H7 platform! Please check your Tools->Board setting.
 #endif
 
 #ifndef PORTENTA_H7_TIMER_INTERRUPT_VERSION

src_cpp/Portenta_H7_ISR_Timer.h

@@ -31,10 +31,8 @@
 #ifndef ISR_TIMER_GENERIC_H
 #define ISR_TIMER_GENERIC_H
 
-#if !( defined(STM32F0) || defined(STM32F1) || defined(STM32F2) || defined(STM32F3)  ||defined(STM32F4) || defined(STM32F7) || \
-       defined(STM32L0) || defined(STM32L1) || defined(STM32L4) || defined(STM32H7)  ||defined(STM32G0) || defined(STM32G4) || \
-       defined(STM32WB) || defined(STM32MP1) || defined(STM32L5))
-  //#error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting.
+#if !( ( defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4) ) && defined(ARDUINO_ARCH_MBED) )
+  #error This code is intended to run on the MBED ARDUINO_PORTENTA_H7 platform! Please check your Tools->Board setting.
 #endif
 
 #ifndef PORTENTA_H7_TIMER_INTERRUPT_VERSION

src_h/Portenta_H7_ISR_Timer.h

@@ -31,10 +31,8 @@
 #ifndef ISR_TIMER_GENERIC_H
 #define ISR_TIMER_GENERIC_H
 
-#if !( defined(STM32F0) || defined(STM32F1) || defined(STM32F2) || defined(STM32F3)  ||defined(STM32F4) || defined(STM32F7) || \
-       defined(STM32L0) || defined(STM32L1) || defined(STM32L4) || defined(STM32H7)  ||defined(STM32G0) || defined(STM32G4) || \
-       defined(STM32WB) || defined(STM32MP1) || defined(STM32L5))
-  //#error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting.
+#if !( ( defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4) ) && defined(ARDUINO_ARCH_MBED) )
+  #error This code is intended to run on the MBED ARDUINO_PORTENTA_H7 platform! Please check your Tools->Board setting.
 #endif
 
 #ifndef PORTENTA_H7_TIMER_INTERRUPT_VERSION
@@ -55,12 +53,12 @@
   #endif
 #endif
 
-#define PORTENTA_H7_ISR_Timer PORTENTA_H7_ISRTimer
+#define Portenta_H7_ISR_Timer Portenta_H7_ISRTimer
 
 typedef void (*timerCallback)();
 typedef void (*timerCallback_p)(void *);
 
-class PORTENTA_H7_ISR_Timer 
+class Portenta_H7_ISR_Timer 
 {
 
   public:
@@ -70,7 +68,7 @@ class PORTENTA_H7_ISR_Timer
 #define TIMER_RUN_ONCE          1
 
     // constructor
-    PORTENTA_H7_ISR_Timer();
+    Portenta_H7_ISR_Timer();
 
     void init();
 
@@ -176,4 +174,8 @@ class PORTENTA_H7_ISR_Timer
     volatile int numTimers;
 };
 
+
+#include "Portenta_H7_ISR_Timer-Impl.h"
+
 #endif    // ISR_TIMER_GENERIC_H
+