root / freemodbus / port / porttimer.c @ 20e5429c
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1 | 20e5429c | Tom Mullins | /*
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2 | * FreeModbus Libary: ATMega168 Port
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3 | * Copyright (C) 2006 Christian Walter <wolti@sil.at>
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4 | *
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5 | * This library is free software; you can redistribute it and/or
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6 | * modify it under the terms of the GNU Lesser General Public
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7 | * License as published by the Free Software Foundation; either
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8 | * version 2.1 of the License, or (at your option) any later version.
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9 | *
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10 | * This library is distributed in the hope that it will be useful,
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 | * Lesser General Public License for more details.
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14 | *
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15 | * You should have received a copy of the GNU Lesser General Public
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16 | * License along with this library; if not, write to the Free Software
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17 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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18 | *
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19 | * File: $Id: porttimer.c,v 1.4 2006/09/03 11:53:10 wolti Exp $
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20 | */
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21 | |||
22 | /* ----------------------- AVR includes -------------------------------------*/
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23 | #include <avr/io.h> |
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24 | #include <avr/interrupt.h> |
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25 | #include <avr/signal.h> |
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26 | |||
27 | /* ----------------------- Platform includes --------------------------------*/
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28 | #include "port.h" |
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29 | |||
30 | /* ----------------------- Modbus includes ----------------------------------*/
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31 | #include "mb.h" |
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32 | #include "mbport.h" |
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33 | |||
34 | /* ----------------------- Defines ------------------------------------------*/
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35 | #define MB_TIMER_PRESCALER ( 1024UL ) |
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36 | #define MB_TIMER_TICKS ( F_CPU / MB_TIMER_PRESCALER )
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37 | #define MB_50US_TICKS ( 20000UL ) |
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38 | |||
39 | /* ----------------------- Static variables ---------------------------------*/
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40 | static USHORT usTimerOCRADelta;
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41 | static USHORT usTimerOCRBDelta;
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42 | |||
43 | /* ----------------------- Start implementation -----------------------------*/
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44 | BOOL |
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45 | xMBPortTimersInit( USHORT usTim1Timerout50us ) |
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46 | { |
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47 | /* Calculate overflow counter an OCR values for Timer1. */
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48 | usTimerOCRADelta = |
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49 | ( MB_TIMER_TICKS * usTim1Timerout50us ) / ( MB_50US_TICKS ); |
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50 | |||
51 | TCCR1A = 0x00;
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52 | TCCR1B = 0x00;
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53 | TCCR1C = 0x00;
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54 | |||
55 | vMBPortTimersDisable( ); |
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56 | |||
57 | return TRUE;
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58 | } |
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59 | |||
60 | |||
61 | inline void |
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62 | vMBPortTimersEnable( ) |
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63 | { |
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64 | TCNT1 = 0x0000;
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65 | if( usTimerOCRADelta > 0 ) |
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66 | { |
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67 | TIMSK1 |= _BV( OCIE1A ); |
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68 | OCR1A = usTimerOCRADelta; |
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69 | } |
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70 | |||
71 | TCCR1B |= _BV( CS12 ) | _BV( CS10 ); |
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72 | } |
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73 | |||
74 | inline void |
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75 | vMBPortTimersDisable( ) |
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76 | { |
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77 | /* Disable the timer. */
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78 | TCCR1B &= ~( _BV( CS12 ) | _BV( CS10 ) ); |
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79 | /* Disable the output compare interrupts for channel A/B. */
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80 | TIMSK1 &= ~( _BV( OCIE1A ) ); |
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81 | /* Clear output compare flags for channel A/B. */
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82 | TIFR1 |= _BV( OCF1A ) ; |
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83 | } |
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84 | |||
85 | SIGNAL( SIG_OUTPUT_COMPARE1A ) |
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86 | { |
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87 | ( void )pxMBPortCBTimerExpired( );
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88 | } |
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89 |