Merge pull request #23 from sensometafisico/master

BXCAN_BUSYWAIT_DELAY_SYSTEM_CORE_CLOCK auto retrieve

Author: pavel-kirienko

stm32/libcanard/bxcan/src/bxcan.c

@@ -15,8 +15,14 @@
 
 /// Configure the system core clock frequency in Hz.
 /// Only used by the busy wait in waitMSRINAKBitStateChange().
-#if !defined(BXCAN_BUSYWAIT_DELAY_SYSTEM_CORE_CLOCK)
-#    error "Please set BXCAN_BUSYWAIT_DELAY_SYSTEM_CORE_CLOCK to the current system core clock."
+/// If using official HAL from ST, set to global variable SystemCoreClock
+#if defined(USE_HAL_DRIVER) && USE_HAL_DRIVER
+extern uint32_t SystemCoreClock;
+#    define BXCAN_BUSYWAIT_DELAY_SYSTEM_CORE_CLOCK SystemCoreClock
+#else
+#    if !defined(BXCAN_BUSYWAIT_DELAY_SYSTEM_CORE_CLOCK)
+#        error "Please set BXCAN_BUSYWAIT_DELAY_SYSTEM_CORE_CLOCK to the current system core clock."
+#    endif
 #endif
 
 /// By default, this macro resolves to the standard assert(). The user can redefine this if necessary.