93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
/*
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Paparazzi mcu0 timer functions
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Copied from autopilot (autopilot.sf.net) thanx alot Trammell
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Copyright (C) 2002 Trammell Hudson <hudson@rotomotion.com>
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Copyright (C) 2003 Pascal Brisset, Antoine Drouin
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This file is part of paparazzi.
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paparazzi is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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paparazzi is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with paparazzi; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA.
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*/
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#ifndef TIMER_H
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#define TIMER_H
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#include "std.h"
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#include <arch/signal.h>
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#include <arch/io.h>
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/*
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Enable Timer1 (16-bit) running at Clk/1 for the global system
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clock. This will be used for computing the servo pulse widths,
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PPM decoding, etc.
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Low frequency periodic tasks will be signaled by timer 0
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running at Clk/1024. For 16 Mhz clock, this will be every
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262144 microseconds, or 61 Hz.
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*/
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static inline void timer_init( void )
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{
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/* Timer0: Modem clock is started in modem.h in ctc mode*/
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/* Timer1 @ Clk/1: System clock, ppm and servos */
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TCCR1A = 0x00;
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TCCR1B = 0x01;
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/* Timer2 @ Clk/1024: Periodic clock */
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TCCR2 = 0x05;
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}
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/*
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Retrieve the current time from the global clock in Timer1,
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disabling interrupts to avoid stomping on the TEMP register.
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If interrupts are already off, the non_atomic form can be used.
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*/
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static inline uint16_t
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timer_now( void )
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{
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return TCNT1;
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}
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static inline uint16_t
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timer_now_non_atomic( void )
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{
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return TCNT1L;
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}
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/*
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Periodic tasks occur when Timer2 overflows. Check and unset
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the overflow bit. We cycle through four possible periodic states,
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so each state occurs every 30 Hz.
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*/
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static inline bool_t
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timer_periodic( void )
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{
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if ( !bit_is_set( TIFR, TOV2 ) )
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return FALSE;
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TIFR = 1 << TOV2;
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return TRUE;
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}
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#endif
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