From 55b33a20a69479219745172575c4504acd52730d Mon Sep 17 00:00:00 2001 From: schodet Date: Wed, 29 Sep 2004 21:07:25 +0000 Subject: Initial revision --- n/asserv/src/pwm.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 n/asserv/src/pwm.c (limited to 'n/asserv/src/pwm.c') diff --git a/n/asserv/src/pwm.c b/n/asserv/src/pwm.c new file mode 100644 index 0000000..84791d4 --- /dev/null +++ b/n/asserv/src/pwm.c @@ -0,0 +1,92 @@ +/* pwm.c */ +/* {{{ + * + * Copyright (C) 2004 Nicolas Schodet + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Contact : + * Web: http://perso.efrei.fr/~schodet/ + * Email: + * }}} */ +#include "pwm.h" +#include + +/* +AutoDec */ +/* -AutoDec */ + +inline void +pwm_init (void) +{ + /* No timer/counter interrupt. */ + //TIMSK = 0; + //ETIMSK = 0; + /* Phase correct PWM, TOP = 0xff, OC1B & OC1C with positive logic. + f_IO without prescaler. + Fpwm = f_IO / (2 * prescaler * TOP) = 28912 Hz. */ + TCCR1A = _BV (COM1B1) | _BV (COM1C1) | _BV (WGM10); + TCCR1B = _BV (CS10); + /* Enable pwm and direction outputs in DDRB. */ + DDRB |= _BV (7) | _BV (6) | _BV (3) | _BV (2); +} + +static inline int16_t +pwm_preproc (int16_t v) +{ + v = (v >> 2) + ((v >> 1) & 1); + /*if (v > 0) + v += 0x0f; + else if (v < 0) + v -= 0x0f;*/ + if (v > 255) + return 255; + else if (v < -255) + return -255; + else + return v; +} + +inline void +pwm_set_left (int16_t v) +{ + v = pwm_preproc (v); + if (v < 0) + { + PORTB &= ~_BV (2); + OCR1B = -v; + } + else + { + PORTB |= _BV (2); + OCR1B = v; + } +} + +inline void +pwm_set_right (int16_t v) +{ + v = pwm_preproc (v); + if (v < 0) + { + PORTB |= _BV (3); + OCR1C = -v; + } + else + { + PORTB &= ~_BV (3); + OCR1C = v; + } +} + -- cgit v1.2.3