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authorJérémy Dufour2009-03-14 23:24:12 +0100
committerJérémy Dufour2009-03-14 23:24:12 +0100
commit734dd6aa329098105a1a2a744ca73443dab44595 (patch)
tree8e963422c9a39bf21f459ffa85d694f926e15b5a /digital/io/src/main_timer.h
parent37cab30b6630eb272fab63f3e080185740aca763 (diff)
* digital/io:
- clean main timer module, - update chrono module to rely on main timer (timer/counter 0).
Diffstat (limited to 'digital/io/src/main_timer.h')
-rw-r--r--digital/io/src/main_timer.h21
1 files changed, 15 insertions, 6 deletions
diff --git a/digital/io/src/main_timer.h b/digital/io/src/main_timer.h
index 1b69a743..3f582f95 100644
--- a/digital/io/src/main_timer.h
+++ b/digital/io/src/main_timer.h
@@ -37,21 +37,26 @@
*/
/**
- * Configuration of prescaler of timer/counter 0.
+ * Prescaler configured for timer/counter 0.
+ * If you want to change this value, you also need to change the TCCR0
+ * register.
*/
-#define MT_TC0_PRESCALER 256
+#define MT_TC0_PRESCALER 256L
/**
- * Configuration of the top of timer/counter 0.
+ * Top configured for timer/counter 0.
+ * If you want to change this value, you also need to change the TCCR0
+ * register.
*/
#define MT_TC0_TOP 255
/**
- * Configuration of the period timer/counter 0 (in millisecond).
+ * Period of timer/counter 0 (in millisecond).
*/
-#define MT_TC0_PERIOD ((1 / AC_FREQ / MT_TC0_PRESCALER * (MT_TC0_TOP + 1)) \
- * 1000)
+#define MT_TC0_PERIOD \
+ (1000 / (AC_FREQ / (MT_TC0_PRESCALER * (MT_TC0_TOP + 1))))
/**
* Initialize the main timer to 4.444 ms.
+ * This function setup the timer/counter 0 configuration register.
*/
void
main_timer_init (void);
@@ -62,6 +67,10 @@ main_timer_init (void);
* - 0 if we are on time (we have not reached overflow before calling this
* function).
* - 1 if we have already reached overflow.
+ * @warning if this function return 1, it means we are late and the main loop
+ * is lasting more than the time configured. Consequence, some important
+ * functions (like the chronometer for match duration) will not work
+ * correctly!
*/
uint8_t
main_timer_wait (void);