Add main loop cycle counter for debugging

stm-firmware/main.c

@@ -218,6 +218,7 @@ int main(void)
 	shellmatta_handle_t shell_handle;
 	int menu_wait_request;
 	uint64_t quarter_sec_timestamp = 0ULL;
+	static uint64_t IN_SECTION(.ccm.bss) main_loop_iter_count;
 
 	setup_system();
 
@@ -267,6 +268,7 @@ int main(void)
 			__WFI();
 		else
 			__NOP();
+		main_loop_iter_count++;
 	}
 
 	return 0;