Use us_ticker_read while SDK is not ready

Author: bcostm

targets/TARGET_STM/hal_tick_common.c

@@ -17,9 +17,19 @@
 
 // Overwrite default HAL functions defined as "weak"
 
+// This variable is set to 1 at the of mbed_sdk_init function.
+// The ticker_read_us function must not be called until the mbed_sdk_init is terminated.
+extern int mbed_sdk_inited;
+
 uint32_t HAL_GetTick()
 {
-    return ticker_read_us(get_us_ticker_data()) / 1000; // 1 ms tick is required for ST HAL
+    // 1 ms tick is required for ST HAL driver
+    if (mbed_sdk_inited) {
+        return (ticker_read_us(get_us_ticker_data()) / 1000);
+    }
+    else {
+        return (us_ticker_read() / 1000);
+    }
 }
 
 void HAL_SuspendTick(void)

targets/TARGET_STM/mbed_overrides.c

@@ -27,6 +27,8 @@
  */
 #include "cmsis.h"
 
+int mbed_sdk_inited = 0;
+
 // This function is called after RAM initialization and before main.
 void mbed_sdk_init()
 {
@@ -51,4 +53,6 @@ void mbed_sdk_init()
        AHB/APBx prescalers and Flash settings */
     SetSysClock();
     SystemCoreClockUpdate();
+
+    mbed_sdk_inited = 1;
 }