app/test_ARMBoard_pwm/pwm.c

   1 /*
   2 *  C Implementation: pwm
   3 *
   4 * Description: configuration of PWM unit
   5 *
   6 *
   7 * Author: LAGARRIGUE <glagarri@etud.insa-toulouse.fr>, (C) 2005
   8 *
   9 * Copyright: See COPYING file that comes with this distribution
  10 *
  11 */
  12
  13
  14 #include <LPC210x.h>
  15 #include "config.h"
  16 #include "pwm.h"
  17
  18 #define MINFREQ  (PCLK/(0xFFFFFFFF))
  19
  20 /**
  21  * Initializes PWM frequency with match0 register
  22  * @param freq   frequency in Hz
  23  */
  24 void Init_PWM(int freq)
  25 {
  26     if ((freq <= PCLK) | (freq >= MINFREQ))
  27     {
  28         PWMPR  = 0x00000000;    //no prescaler
  29         PWMMCR = 0x00000002;    // on match with MATCH0 Register, reset the counter
  30         PWMMR0 = (int)(PCLK/(freq));
  31     }
  32
  33
  34 }
  35
  36 /**
  37  * Initilizes and sets the duty cycle of the desired pwm channel
  38  * @param channel   = channel number (1,2,3,4,5,6)
  39  * @param duty_cycle  = float between 0 and 1
  40  */
  41 void Set_PWM (int channel, float duty_cycle)
  42 {
  43         int Pwmmatch;
  44         Pwmmatch = (int) (duty_cycle * PWMMR0);
  45
  46
  47
  48         //PINSEL0 |= ...;                    /* Enable P0.7, 8 and P0.9 as alternate PWM outputs functions*/
  49         //PINSEL0 &= ...;
  50
  51         //PWMPCR = ...;                      /* single edge control only*/
  52
  53         //PWMMRX = 0x500;                           /* set falling edge of PWM channel X       */
  54
  55         //PWMLER = 0x..;                             /* enable shadow latch for match 1 - 6   */
  56
  57
  58         switch (channel)
  59     {
  60
  61
  62         case 1 :
  63             PWMMR1 =Pwmmatch;
  64                 PWMPCR |= 0x0200;
  65                 PWMLER |= 0x02;
  66                 PINSEL0 |= 0x00000002;
  67                 PINSEL0 &= 0xFFFFFFFE;
  68                 break;
  69
  70         case 2 :
  71                 PWMMR2 =Pwmmatch;
  72                 PWMPCR |= 0x0400;
  73                 PWMLER |= 0x04;
  74                 PINSEL0 |= 0x00008000;
  75                 PINSEL0 &= 0xFFFFBFFF;
  76                 break;
  77
  78         case 3 :
  79             PWMMR3 =Pwmmatch;
  80                 PWMPCR |= 0x0800;
  81                 PWMLER |= 0x08;
  82                 PINSEL0 |= 0x00000008;
  83                 PINSEL0 &= 0xFFFFFFFB;
  84                 break;
  85         case 4 :
  86             PWMMR4 =Pwmmatch;
  87                 PWMPCR |= 0x1000;
  88                 PWMLER |= 0x10;
  89                 PINSEL0 |= 0x00020000;
  90                 PINSEL0 &= 0xFFFEFFFF;
  91                 break;
  92
  93         case 5 :
  94             PWMMR5 =Pwmmatch;
  95                 PWMPCR |= 0x2000;
  96                 PWMLER |= 0x20;
  97                 PINSEL1 |= 0x00000400;
  98                 PINSEL1 &= 0xFFFFF7FF;
  99                 break;
 100
 101         case 6 :
 102                 PWMMR6 =Pwmmatch;
 103                 PWMPCR |= 0x4000;
 104                 PWMLER |= 0x40;
 105                 PINSEL0 |= 0x00080000;
 106                 PINSEL0 &= 0xFFFBFFFF;
 107                 break;
 108
 109
 110     }
 111
 112 }
 113
 114
 115 /**
 116  * Resets the counter and runs the PWM unit
 117  * @param
 118  */
 119 void Run_PWM (void)
 120 {
 121     PWMTCR = 0x2;                      /* Reset counter and prescaler           */
 122     PWMTCR = 0x9;                      /* enable counter and PWM, release counter from reset */
 123 }
 124
 125
 126 /**
 127  * Stops PWM unit and resets the timer
 128  * @param
 129  */
 130 void Stop_PWM (void)
 131 {
 132     int i;
 133     for (i=1 ; i < 7 ; i++)
 134         {
 135             Set_PWM (i, 0);
 136         }
 137     PWMTCR = 0x2;
 138 }