Kari Argillander
cb243c36a8
* Change MIT license texts to SPDX-License-Identifier SPDX-License-Identifier is much easier to understand and grep than license text so use that instead. * Change GPL exception license texts to SPDX-License-Identifier SPDX-License-Identifier is much easier to understand and grep than license text so use that instead. * Change misc license texts to SPDX-License-Identifier There are some external code in repo which are not licenses as most of the stuff in this repo. We still want every file to have SPDX identifier to easily grep licenses. * Add currently used license files Even though Bacnet-Stack is using SPDX identifiers we still need to give those license files with source. For this reason add all license files to license/ folder. SPDX has also files which would make same thing but this is style which example Linux kernel is using and it is quite clear so I choose that one for now. I choosed not yet bring CC-PDDC as that is not right license for those files. --------- Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>
133 lines
4.2 KiB
C
133 lines
4.2 KiB
C
/**************************************************************************
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*
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* Copyright (C) 2009 Steve Karg <skarg@users.sourceforge.net>
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*
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* SPDX-License-Identifier: MIT
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*
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*********************************************************************/
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#include <stdbool.h>
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#include <stdint.h>
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#include "hardware.h"
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#include "bacnet/basic/sys/mstimer.h"
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#ifndef F_CPU
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#error "F_CPU must be defined for Timer configuration."
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#endif
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/* Timer2 Prescaling: 1, 8, 32, 64, 128, 256, or 1024 */
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#define TIMER_MICROSECONDS 1000UL
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#define TIMER_TICKS(p) \
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(((((F_CPU) / (p)) / 1000UL) * (TIMER_MICROSECONDS)) / 1000UL)
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#define TIMER_TICKS_MAX 255UL
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/* adjust the prescaler for the processor clock */
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#if (TIMER_TICKS(1) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 1
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#elif (TIMER_TICKS(8) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 8
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#elif (TIMER_TICKS(32) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 32
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#elif (TIMER_TICKS(64) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 64
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#elif (TIMER_TICKS(128) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 128
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#elif (TIMER_TICKS(256) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 256
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#elif (TIMER_TICKS(1024) <= TIMER_TICKS_MAX)
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#define TIMER2_PRESCALER 1024
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#else
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#error "TIMER2: F_CPU too large for timer prescaler."
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#endif
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#define TIMER2_TICKS TIMER_TICKS(TIMER2_PRESCALER)
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/* Timer counts up from count to TIMER_TICKS_MAX and then signals overflow */
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#define TIMER2_COUNT (TIMER_TICKS_MAX - TIMER2_TICKS)
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/* counter for the the timer which wraps every 49.7 days */
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static volatile uint32_t Millisecond_Counter;
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/*************************************************************************
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* Description: Timer Interrupt Handler
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* Returns: nothing
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* Notes: none
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*************************************************************************/
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static inline void timer_interrupt_handler(void)
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{
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/* Set the counter for the next interrupt */
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TCNT2 = TIMER2_COUNT;
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Millisecond_Counter++;
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}
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/*************************************************************************
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* Description: Timer Interrupt Service Routine - Timer Overflowed!
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* Returns: none
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* Notes: Global interupts must be enabled
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*************************************************************************/
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ISR(TIMER2_OVF_vect)
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{
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timer_interrupt_handler();
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}
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/*************************************************************************
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* Description: returns the current millisecond count
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* Returns: none
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* Notes: This method only disables the timer overflow interrupt.
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*************************************************************************/
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unsigned long mstimer_now(void)
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{
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unsigned long timer_value; /* return value */
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/* Disable the overflow interrupt.
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Prevents value corruption that would happen if interrupted */
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BIT_CLEAR(TIMSK2, TOIE2);
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timer_value = Millisecond_Counter;
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/* Enable the overflow interrupt */
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BIT_SET(TIMSK2, TOIE2);
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return timer_value;
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}
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/*************************************************************************
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* Description: Initialization for Timer
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* Returns: none
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* Notes: none
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*************************************************************************/
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void mstimer_init(void)
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{
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/* Normal Operation */
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TCCR2A = 0;
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/* Timer2: prescale selections:
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CSn2 CSn1 CSn0 Description
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---- ---- ---- -----------
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0 0 0 No Clock Source
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0 0 1 No prescaling
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0 1 0 CLKt2s/8
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0 1 1 CLKt2s/32
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1 0 0 CLKt2s/64
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1 0 1 CLKt2s/128
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1 1 0 CLKt2s/256
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1 1 1 CLKt2s/1024
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*/
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#if (TIMER2_PRESCALER == 1)
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TCCR2B = _BV(CS20);
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#elif (TIMER2_PRESCALER == 8)
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TCCR2B = _BV(CS21);
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#elif (TIMER2_PRESCALER == 32)
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TCCR2B = _BV(CS21) | _BV(CS20);
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#elif (TIMER2_PRESCALER == 64)
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TCCR2B = _BV(CS22);
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#elif (TIMER2_PRESCALER == 128)
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TCCR2B = _BV(CS22) | _BV(CS20);
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#elif (TIMER2_PRESCALER == 256)
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TCCR2B = _BV(CS22) | _BV(CS21);
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#elif (TIMER2_PRESCALER == 1024)
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TCCR2B = _BV(CS22) | _BV(CS21) | _BV(CS20);
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#else
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#error Timer2 Prescale: Invalid Value
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#endif
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/* Clear any TOV Flag set when the timer overflowed - by setting! */
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BIT_SET(TIFR2, TOV2);
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/* Initial value */
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TCNT2 = TIMER2_COUNT;
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/* Enable the overflow interrupt */
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BIT_SET(TIMSK2, TOIE2);
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power_timer2_enable();
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}
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