Fix timer HW test

Author: P-R-O-C-H-Y

tests/timer/timer.ino

@@ -11,31 +11,29 @@
  * S3 - APB + XTAL clk
  */
 
-hw_timer_t * timer = NULL;
-hw_timer_t * timer_XTAL = NULL;
+static hw_timer_t * timer = NULL;
 static volatile bool alarm_flag;
 
-/* These functions are intended to be called before and after each test. */
+/* setUp / tearDown functions are intended to be called before / after each test. */
 void setUp(void) {
   timer = timerBegin(TIMER_FREQUENCY);
+  if(timer == NULL){
+     TEST_FAIL_MESSAGE("Timer init failed in setUp()");
+  }
   timerStop(timer);
   timerRestart(timer);
 }
 
 void tearDown(void){
   timerEnd(timer);
-  timer = NULL;
 }
 
-
-
 void ARDUINO_ISR_ATTR onTimer(){
   alarm_flag = true;
 }
 
-
 void timer_interrupt_test(void){
-  
+
   alarm_flag = false;
   timerAttachInterrupt(timer, &onTimer);
   timerAlarm(timer, (1.2 * TIMER_FREQUENCY), true, 0);
@@ -67,9 +65,11 @@ void timer_divider_test(void){
 
   // compare divider  16 and 8, value should be double
   timerEnd(timer);
-  timer = NULL;
 
   timer = timerBegin(2 * TIMER_FREQUENCY);
+  if(timer == NULL){
+     TEST_FAIL_MESSAGE("Timer init failed!");
+  }
   timerRestart(timer);
   delay(1000);        
   comp_time_val = timerRead(timer);
@@ -79,9 +79,11 @@ void timer_divider_test(void){
 
   // divider is 256, value should be 2^4
   timerEnd(timer);
-  timer = NULL;
 
   timer = timerBegin(TIMER_FREQUENCY / 16);
+  if(timer == NULL){
+     TEST_FAIL_MESSAGE("Timer init failed!");
+  }
   timerRestart(timer);
   delay(1000);       
   comp_time_val = timerRead(timer);
@@ -103,13 +105,10 @@ void timer_read_test(void){
 
 void timer_clock_select_test(void){
   // Set timer frequency that can be achieved using XTAL clock source (autoselected)
-  timer_XTAL = timerBegin(TIMER_FREQUENCY_XTAL_CLK);
+  timer = timerBegin(TIMER_FREQUENCY_XTAL_CLK);
 
-  uint32_t resolution = timerGetFrequency(timer_XTAL);
+  uint32_t resolution = timerGetFrequency(timer);
   TEST_ASSERT_EQUAL(TIMER_FREQUENCY_XTAL_CLK,resolution);
-  
-  timerEnd(timer_XTAL);
-  timer_XTAL = NULL;
 }
 
 void setup(){
@@ -131,4 +130,4 @@ void setup(){
 }
 
 void loop(){
-}
+}