tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC82X/pwmout_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #include "mbed_assert.h"
  17 #include "pwmout_api.h"
  18 #include "cmsis.h"
  19 #include "pinmap.h"
  20 #include "mbed_error.h"
  21
  22 #if DEVICE_PWMOUT
  23
  24 // bit flags for used SCTs
  25 static unsigned char sct_used = 0;
  26
  27 static int get_available_sct()
  28 {
  29     int i;
  30     for (i = 0; i < 4; i++) {
  31         if ((sct_used & (1 << i)) == 0)
  32             return i;
  33     }
  34     return -1;
  35 }
  36
  37 void pwmout_init(pwmout_t* obj, PinName pin)
  38 {
  39     MBED_ASSERT(pin != (uint32_t)NC);
  40
  41     int sct_n = get_available_sct();
  42     if (sct_n == -1) {
  43         error("No available SCT");
  44     }
  45
  46     sct_used |= (1 << sct_n);
  47
  48     obj->pwm =  (LPC_SCT_Type*)LPC_SCT;
  49     obj->pwm_ch = sct_n;
  50
  51     LPC_SCT_Type* pwm = obj->pwm;
  52
  53     // Enable the SCT clock
  54     LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 8);
  55
  56     // Clear peripheral reset the SCT:
  57     LPC_SYSCON->PRESETCTRL |=  (1 << 8);
  58
  59     switch(sct_n) {
  60         case 0:
  61             // SCT_OUT0
  62             LPC_SWM->PINASSIGN[7] &= ~0xFF000000;
  63             LPC_SWM->PINASSIGN[7] |= ((pin >> PIN_SHIFT) << 24);
  64             break;
  65         case 1:
  66             // SCT_OUT1
  67             LPC_SWM->PINASSIGN[8] &= ~0x000000FF;
  68             LPC_SWM->PINASSIGN[8] |= (pin >> PIN_SHIFT);
  69             break;
  70         case 2:
  71             // SCT2_OUT2
  72             LPC_SWM->PINASSIGN[8] &= ~0x0000FF00;
  73             LPC_SWM->PINASSIGN[8] |= ((pin >> PIN_SHIFT) << 8);
  74             break;
  75         case 3:
  76             // SCT3_OUT3
  77             LPC_SWM->PINASSIGN[8] &= ~0x00FF0000;
  78             LPC_SWM->PINASSIGN[8] |= ((pin >> PIN_SHIFT) << 16);
  79             break;
  80         default:
  81             break;
  82     }
  83
  84     // Unified 32-bit counter, autolimit
  85     pwm->CONFIG |= ((0x3 << 17) | 0x01);
  86
  87     // halt and clear the counter
  88     pwm->CTRL |= (1 << 2) | (1 << 3);
  89
  90     // System Clock -> us_ticker (1)MHz
  91     pwm->CTRL &= ~(0x7F << 5);
  92     pwm->CTRL |= (((SystemCoreClock/1000000 - 1) & 0x7F) << 5);
  93
  94     pwm->OUT[sct_n].SET = (1 << ((sct_n * 2) + 0));
  95     pwm->OUT[sct_n].CLR = (1 << ((sct_n * 2) + 1));
  96
  97     pwm->EVENT[(sct_n * 2) + 0].CTRL  = (1 << 12) | ((sct_n * 2) + 0);  // match event
  98     pwm->EVENT[(sct_n * 2) + 0].STATE = 0xFFFFFFFF;
  99     pwm->EVENT[(sct_n * 2) + 1].CTRL  = (1 << 12) | ((sct_n * 2) + 1);
 100     pwm->EVENT[(sct_n * 2) + 1].STATE = 0xFFFFFFFF;
 101
 102     // unhalt the counter:
 103     //    - clearing bit 2 of the CTRL register
 104     pwm->CTRL &= ~(1 << 2);
 105
 106     // default to 20ms: standard for servos, and fine for e.g. brightness control
 107     pwmout_period_ms(obj, 20);
 108     pwmout_write    (obj, 0);
 109 }
 110
 111 void pwmout_free(pwmout_t* obj)
 112 {
 113     // Disable the SCT clock
 114     LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 8);
 115     sct_used &= ~(1 << obj->pwm_ch);
 116 }
 117
 118 void pwmout_write(pwmout_t* obj, float value)
 119 {
 120     if (value < 0.0f) {
 121         value = 0.0;
 122     } else if (value > 1.0f) {
 123         value = 1.0;
 124     }
 125     uint32_t t_on = (uint32_t)((float)(obj->pwm->MATCHREL[obj->pwm_ch * 2]) * value);
 126     obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] = t_on;
 127 }
 128
 129 float pwmout_read(pwmout_t* obj)
 130 {
 131     uint32_t t_off = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 0];
 132     uint32_t t_on  = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1];
 133     float v = (float)t_on/(float)t_off;
 134     return (v > 1.0f) ? (1.0f) : (v);
 135 }
 136
 137 void pwmout_period(pwmout_t* obj, float seconds)
 138 {
 139     pwmout_period_us(obj, seconds * 1000000.0f);
 140 }
 141
 142 void pwmout_period_ms(pwmout_t* obj, int ms)
 143 {
 144     pwmout_period_us(obj, ms * 1000);
 145 }
 146
 147 // Set the PWM period, keeping the duty cycle the same.
 148 void pwmout_period_us(pwmout_t* obj, int us)
 149 {
 150     uint32_t t_off = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 0];
 151     uint32_t t_on  = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1];
 152     float v = (float)t_on/(float)t_off;
 153     obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 0] = (uint32_t)us;
 154     obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] = (uint32_t)((float)us * (float)v);
 155 }
 156
 157 void pwmout_pulsewidth(pwmout_t* obj, float seconds)
 158 {
 159     pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
 160 }
 161
 162 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms)
 163 {
 164     pwmout_pulsewidth_us(obj, ms * 1000);
 165 }
 166
 167 void pwmout_pulsewidth_us(pwmout_t* obj, int us)
 168 {
 169     obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] = (uint32_t)us;
 170 }
 171
 172 #endif