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Added pre-compiler logic for configuring the Timer pre-scaler for any given CPU frequency.

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This commit is contained in:
skarg
2010-08-26 17:43:25 +00:00
parent 0dcc38b020
commit e49263915f
1 changed files with 26 additions and 7 deletions
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bacnet-stack/ports/bdk-atxx4-mstp/timer2.c
+26 -7
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@@ -26,14 +26,33 @@
#include "hardware.h"
#include "timer.h"
/* Timer2 Prescaling: 1, 8, 32, 64, 128, 256, or 1024 */
#define TIMER2_PRESCALER 128
/* Count: Timer counts up to 0xFF and then signals overflow */
#define TIMER2_TICKS (F_CPU/TIMER2_PRESCALER/1000)
#if (TIMER2_TICKS > 0xFF)
#error Timer2 Prescaler value is too small
#ifndef F_CPU
#error "F_CPU must be defined for Timer configuration."
#endif
#define TIMER2_COUNT (0xFF-TIMER2_TICKS)
/* Timer2 Prescaling: 1, 8, 32, 64, 128, 256, or 1024 */
#define TIMER_TICKS(p) (F_CPU/(p)/1000)
#define TIMER_TICKS_MAX 0xff
/* adjust the prescaler for the processor clock */
#if (TIMER_TICKS(1) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 1
#elif (TIMER_TICKS(8) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 8
#elif (TIMER_TICKS(32) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 32
#elif (TIMER_TICKS(64) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 64
#elif (TIMER_TICKS(128) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 128
#elif (TIMER_TICKS(256) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 256
#elif (TIMER_TICKS(1024) <= TIMER_TICKS_MAX)
#define TIMER2_PRESCALER 1024
#else
#error "TIMER2: F_CPU too large for timer prescaler."
#endif
#define TIMER2_TICKS TIMER_TICKS(TIMER2_PRESCALER)
/* Timer counts up from count to TIMER_TICKS_MAX and then signals overflow */
#define TIMER2_COUNT (TIMER_TICKS_MAX-TIMER2_TICKS)
/* counter for the the timer which wraps every 49.7 days */
static volatile uint32_t Millisecond_Counter;