Steve Karg
4781582204
* Changed ATmega168 example for ATmega328 on Arduino Uno R3 with DFR0259 RS485 shield. Added ADC interface from BDK port and mapped to some AV objects. Removed MS/TP MAC address DIP switch GPIO and moved MS/TP configuration to AV objects. Added AV units property. Added some Uno R3 Digital Inputs and outputs mapped to some BV. Added AVR EEPROM from BDK port and mapped some non-volatile data including MAC address and max manager and baud rate, device ID and names and description and location.
102 lines
2.8 KiB
C
102 lines
2.8 KiB
C
/**
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* @brief This module handles the 1 millisecond timer for the mstimer library
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* @author Steve Karg <skarg@users.sourceforge.net>
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* @date 2007
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* @copyright SPDX-License-Identifier: MIT
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*/
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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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/* Prescaling: 1, 8, 64, 256, 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 TIMER0_PRESCALER 1
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#elif (TIMER_TICKS(8) <= TIMER_TICKS_MAX)
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#define TIMER0_PRESCALER 8
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#elif (TIMER_TICKS(64) <= TIMER_TICKS_MAX)
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#define TIMER0_PRESCALER 64
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#elif (TIMER_TICKS(256) <= TIMER_TICKS_MAX)
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#define TIMER0_PRESCALER 256
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#elif (TIMER_TICKS(1024) <= TIMER_TICKS_MAX)
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#define TIMER0_PRESCALER 1024
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#else
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#error "TIMER0: F_CPU too large for timer prescaler."
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#endif
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#define TIMER0_TICKS TIMER_TICKS(TIMER0_PRESCALER)
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/* Timer counts up from count to TIMER_TICKS_MAX and then signals overflow */
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#define TIMER0_COUNT (TIMER_TICKS_MAX - TIMER0_TICKS)
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/* millisecond time counter */
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static volatile unsigned long Millisecond_Counter;
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/* Configure the Timer */
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void mstimer_init(void)
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{
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/* Normal Operation */
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TCCR1A = 0;
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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 CLKio/8
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0 1 1 CLKio/64
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1 0 0 CLKio/256
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1 0 1 CLKio/1024
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1 1 0 Falling Edge of T0 (external)
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1 1 1 Rising Edge of T0 (external)
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*/
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#if (TIMER0_PRESCALER == 1)
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TCCR0B = _BV(CS00);
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#elif (TIMER0_PRESCALER == 8)
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TCCR0B = _BV(CS01);
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#elif (TIMER0_PRESCALER == 64)
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TCCR0B = _BV(CS01) | _BV(CS00);
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#elif (TIMER0_PRESCALER == 256)
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TCCR0B = _BV(CS02);
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#elif (TIMER0_PRESCALER == 1024)
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TCCR0B = _BV(CS02) | _BV(CS00);
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#else
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#error Timer0 Prescale: Invalid Value
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#endif
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/* Clear any TOV1 Flag set when the timer overflowed */
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BIT_CLEAR(TIFR0, TOV0);
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/* Initial value */
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TCNT0 = TIMER0_COUNT;
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/* Enable the overflow interrupt */
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BIT_SET(TIMSK0, TOIE0);
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/* Clear the Power Reduction Timer/Counter0 */
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BIT_CLEAR(PRR, PRTIM0);
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}
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/* Timer interupt */
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/* note: Global interupts must be enabled - sei() */
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/* Timer Overflowed! Increment the time. */
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ISR(TIMER0_OVF_vect)
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{
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/* Set the counter for the next interrupt */
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TCNT0 = TIMER0_COUNT;
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/* Overflow Flag is automatically cleared */
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/* Update the global timer */
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Millisecond_Counter++;
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}
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/**
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* Get the current time in milliseconds
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* @return milliseconds
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*/
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unsigned long mstimer_now(void)
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{
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unsigned long milliseconds;
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BIT_CLEAR(TIMSK0, TOIE0);
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milliseconds = Millisecond_Counter;
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BIT_SET(TIMSK0, TOIE0);
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return milliseconds;
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}
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