- Re-implementation of timing facility using timer0 and the internal clock

source. Using an external clock source (esp. the real-time clock) did not
  work. This  might as well be a local problem (e.g. hardware).
- Provide some dummy implementations in order to fix the build.

cpu/avr/dev/clock.c

@@ -5,46 +5,90 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
 
-// Hack to see if this sets the blue led...
+static clock_time_t count;
-/* #include "hal_emwinet_demoboard.h" */
-
-static unsigned short count;
-
 
 /*---------------------------------------------------------------------------*/
 SIGNAL(SIG_OUTPUT_COMPARE0)
 {
-/*   if ((count % 10) > 5) SET_BLUE_LED(); */
-/*   else CLEAR_BLUE_LED(); */
-
   ++count;
   if(etimer_pending()) {
     etimer_request_poll();
   }
 }
+
+/* External clock source does not work ? */
+#if 0
+void
+clock_init(void)
+{
+  cli ();
+  TIMSK &= ((unsigned char)~(1 << (TOIE0)));
+  TIMSK &= ((unsigned char)~(1 << (OCIE0)));
+  /* Disable TC0 interrupt */
+
+  /** 
+   *  set Timer/Counter0 to be asynchronous 
+   *  from the CPU clock with a second external 
+   *  clock(32,768kHz)driving it
+   */
+  ASSR |= (1 << (AS0));
+  TCCR0 = _BV (CS02) | _BV (CS01) | _BV (WGM1);
+
+  TCNT0 = 0;
+  OCR0 = 128;
+  
+  TIMSK |= (1 << (OCIE0));
+  TIMSK |= (1 << (TOIE0));
+  sei ();
+}
+#endif
+
 /*---------------------------------------------------------------------------*/
 void
 clock_init(void)
 {
-#if 0
+  cli ();
-#if __AVR_ENHANCED__
-  outp(_BV(CS00) | _BV(CS02) | _BV(WGM01), TCCR0);
-#else
-  outp(_BV(CS00) | _BV(CS02) | _BV(CTC0), TCCR0);
-#endif
-  outp(0, TCNT0);
-  outp((NUT_CPU_FREQ / (128L * CLOCK_CONF_SECOND) + 0.5/*round*/), OCR0);
-  sbi(TIMSK, OCIE0);
-#endif /* 0 */
 
+  /* Select internal clock */
+  ASSR = 0x00;
 
-  TCCR0 = _BV(CS00) | _BV(CS02) | _BV(WGM01);
+  /* Set counter to zero */
   TCNT0 = 0;
-  /*  OCR0 = AVR_CLK_COUNT;*/
-  TIMSK |= _BV(OCIE0);
 
+  /*
+   * Set comparison register: 
+   * Crystal freq. is 16000000,
+   * pre-scale factor is 1024, i.e. we have 125 "ticks" / sec:
+   * 16000000 = 1024 * 125 * 125
+   */
+  OCR0 = 125;
+  
+  /*
+   * Set timer control register:
+   *  - prescale: 1024 (CS00 - CS02)
+   *  - counter reset via comparison register (WGM01)
+   */
+  TCCR0 =  _BV(CS00) | _BV(CS01) |  _BV(CS02) |  _BV(WGM01);
+  
+  /* Clear interrupt flag register */
+  TIFR = 0x00;
+
+  /*
+   * Raise interrupt when value in OCR0 is reached. Note that the
+   * counter value in TCNT0 is cleared automatically.
+   */
+  TIMSK = _BV (OCIE0);
+
+  /*
+   * Counts the number of ticks. Since clock_time_t is an unsigned
+   * 16 bit data type, time intervals of up to 524 seconds can be
+   * measured.
+   */
   count = 0;
+
+  sei ();
 }
+
 /*---------------------------------------------------------------------------*/
 clock_time_t
 clock_time(void)
@@ -52,3 +96,37 @@ clock_time(void)
   return count;
 }
 /*---------------------------------------------------------------------------*/
+/**
+ * Delay the CPU for a multiple of TODO
+ */
+void
+clock_delay(unsigned int i)
+{
+    // TODO
+}
+
+/*---------------------------------------------------------------------------*/
+/**
+ * Wait for a multiple of 1 / 125 sec = 0.008 ms.
+ *
+ */
+void
+clock_wait(int i)
+{
+  clock_time_t start;
+
+  start = clock_time();
+  while(clock_time() - start < (clock_time_t)i);
+}
+/*---------------------------------------------------------------------------*/
+void
+clock_set_seconds(unsigned long sec)
+{
+    // TODO
+}
+
+unsigned long
+clock_seconds(void)
+{
+  return count / CLOCK_SECOND;
+}