Fix racy racy code.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@218 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/drv/timer_avr.h b/drv/timer_avr.h
index 0d32701896d59627a1992e5c8a973c5b1a37e942..f8dbaa3dc980a36ecec843d0b45a7fa7d2f3e9c6 100755 (executable)
--- a/drv/timer_avr.h
+++ b/drv/timer_avr.h
@@ -15,6 +15,9 @@
 
 /*#*
  *#* $Log$
+ *#* Revision 1.18  2004/09/20 03:31:03  bernie
+ *#* Fix racy racy code.
+ *#*
  *#* Revision 1.17  2004/09/14 21:07:09  bernie
  *#* Include hw.h explicitly.
  *#*
@@ -233,22 +236,6 @@
         */
        SIGNAL(SIG_OVERFLOW1)
        {
-               /*!
-                * How many overflow we have to count before calling the true timer handler.
-                * If timer overflow is at 24 kHz, with a value of 24 we have 1 ms between
-                * each call.
-                */
-               #define TIMER1_OVF_COUNT 24
-
-               static uint8_t count = TIMER1_OVF_COUNT;
-
-               count--;
-               if (!count)
-               {
-                       timer_handler();
-                       count = TIMER1_OVF_COUNT;
-               }
-
        #if (ARCH & ARCH_BOARD_KC)
                /*
                 * Super-optimization-hack: switch CPU ADC mux here, ASAP after the start
@@ -259,18 +246,49 @@
                 * of the handler.
                 *
                 * The switch is synchronized with the ADC handler using _adc_trigger_lock.
+                *
+                *      Mel (A Real Programmer)
                 */
                extern uint8_t _adc_idx_next;
                extern bool _adc_trigger_lock;
 
                if (!_adc_trigger_lock)
                {
-                       TIMER_STROBE_ON;
+                       /*
+                        * Disable free-running mode to avoid starting a
+                        * new conversion before the ADC handler has read
+                        * the ongoing one.  This condition could occur
+                        * under very high interrupt load and would have the
+                        * unwanted effect of reading from the wrong ADC
+                        * channel.
+                        *
+                        * NOTE: writing 0 to ADSC and ADIF has no effect.
+                        */
+                       ADCSRA = ADCSRA & ~(BV(ADFR) | BV(ADIF) | BV(ADSC));
+
                        ADC_SETCHN(_adc_idx_next);
-                       TIMER_STROBE_OFF;
                        _adc_trigger_lock = true;
                }
-       #endif
+       #endif // ARCH_BOARD_KC
+
+               /*!
+                * How many timer overflows we must count before calling the real
+                * timer handler.
+                * When the timer is programmed to overflow at 24 kHz, a value of
+                * 24 will result in 1ms between each call.
+                */
+               #define TIMER1_OVF_COUNT 24
+               //#warning TIMER1_OVF_COUNT for timer at 12 kHz
+               //#define TIMER1_OVF_COUNT 12
+
+               static uint8_t count = TIMER1_OVF_COUNT;
+
+               count--;
+               if (!count)
+               {
+                       timer_handler();
+                       count = TIMER1_OVF_COUNT;
+               }
        }
 
 #elif (CONFIG_TIMER == TIMER_ON_OUTPUT_COMPARE0)