tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/TARGET_LPC4088/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
  21 #define TCR_CNT_EN       0x00000001
  22 #define TCR_RESET        0x00000002
  23
  24 //  PORT ID, PWM ID, Pin function
  25 static const PinMap PinMap_PWM[] = {
  26     {P1_2,  PWM0_1, 3},
  27     {P1_3,  PWM0_2, 3},
  28     {P1_5,  PWM0_3, 3},
  29     {P1_6,  PWM0_4, 3},
  30     {P1_7,  PWM0_5, 3},
  31     {P1_11, PWM0_6, 3},
  32     {P1_18, PWM1_1, 2},
  33     {P1_20, PWM1_2, 2},
  34     {P1_21, PWM1_3, 2},
  35     {P1_23, PWM1_4, 2},
  36     {P1_24, PWM1_5, 2},
  37     {P1_26, PWM1_6, 2},
  38     {P2_0,  PWM1_1, 1},
  39     {P2_1,  PWM1_2, 1},
  40     {P2_2,  PWM1_3, 1},
  41     {P2_3,  PWM1_4, 1},
  42     {P2_4,  PWM1_5, 1},
  43     {P2_5,  PWM1_6, 1},
  44     {P3_16, PWM0_1, 2},
  45     {P3_17, PWM0_2, 2},
  46     {P3_18, PWM0_3, 2},
  47     {P3_19, PWM0_4, 2},
  48     {P3_20, PWM0_5, 2},
  49     {P3_21, PWM0_6, 2},
  50     {P3_24, PWM1_1, 2},
  51     {P3_25, PWM1_2, 2},
  52     {P3_26, PWM1_3, 2},
  53     {P3_27, PWM1_4, 2},
  54     {P3_28, PWM1_5, 2},
  55     {P3_29, PWM1_6, 2},
  56     {NC, NC, 0}
  57 };
  58
  59 static const uint32_t PWM_mr_offset[7] = {
  60     0x18, 0x1C, 0x20, 0x24, 0x40, 0x44, 0x48
  61 };
  62
  63 #define TCR_PWM_EN       0x00000008
  64 static unsigned int pwm_clock_mhz;
  65
  66 void pwmout_init(pwmout_t* obj, PinName pin) {
  67     // determine the channel
  68     PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
  69     MBED_ASSERT(pwm != (PWMName)NC);
  70
  71     obj->channel = pwm;
  72     obj->pwm = LPC_PWM0;
  73
  74     if (obj->channel > 6) { // PWM1 is used if pwm > 6
  75       obj->channel -= 6;
  76       obj->pwm = LPC_PWM1;
  77     }
  78
  79     obj->MR = (__IO uint32_t *)((uint32_t)obj->pwm + PWM_mr_offset[obj->channel]);
  80
  81     // ensure the power is on
  82     if (obj->pwm == LPC_PWM0) {
  83         LPC_SC->PCONP |= 1 << 5;
  84     } else {
  85         LPC_SC->PCONP |= 1 << 6;
  86     }
  87
  88     obj->pwm->PR = 0;                     // no pre-scale
  89
  90     // ensure single PWM mode
  91     obj->pwm->MCR = 1 << 1; // reset TC on match 0
  92
  93     // enable the specific PWM output
  94     obj->pwm->PCR |= 1 << (8 + obj->channel);
  95
  96     pwm_clock_mhz = PeripheralClock / 1000000;
  97
  98     // default to 20ms: standard for servos, and fine for e.g. brightness control
  99     pwmout_period_ms(obj, 20);
 100     pwmout_write    (obj, 0);
 101
 102     // Wire pinout
 103     pinmap_pinout(pin, PinMap_PWM);
 104 }
 105
 106 void pwmout_free(pwmout_t* obj) {
 107     // [TODO]
 108 }
 109
 110 void pwmout_write(pwmout_t* obj, float value) {
 111     if (value < 0.0f) {
 112         value = 0.0;
 113     } else if (value > 1.0f) {
 114         value = 1.0;
 115     }
 116
 117     // set channel match to percentage
 118     uint32_t v = (uint32_t)((float)(obj->pwm->MR0) * value);
 119
 120     // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout
 121     if (v == obj->pwm->MR0) {
 122         v++;
 123     }
 124
 125     *obj->MR = v;
 126
 127     // accept on next period start
 128     obj->pwm->LER |= 1 << obj->channel;
 129 }
 130
 131 float pwmout_read(pwmout_t* obj) {
 132     float v = (float)(*obj->MR) / (float)(obj->pwm->MR0);
 133     return (v > 1.0f) ? (1.0f) : (v);
 134 }
 135
 136 void pwmout_period(pwmout_t* obj, float seconds) {
 137     pwmout_period_us(obj, seconds * 1000000.0f);
 138 }
 139
 140 void pwmout_period_ms(pwmout_t* obj, int ms) {
 141     pwmout_period_us(obj, ms * 1000);
 142 }
 143
 144 // Set the PWM period, keeping the duty cycle the same.
 145 void pwmout_period_us(pwmout_t* obj, int us) {
 146     // calculate number of ticks
 147     uint32_t ticks = pwm_clock_mhz * us;
 148
 149     // set reset
 150     obj->pwm->TCR = TCR_RESET;
 151
 152     // set the global match register
 153     obj->pwm->MR0 = ticks;
 154
 155     // Scale the pulse width to preserve the duty ratio
 156     if (obj->pwm->MR0 > 0) {
 157         *obj->MR = (*obj->MR * ticks) / obj->pwm->MR0;
 158     }
 159
 160     // set the channel latch to update value at next period start
 161     obj->pwm->LER |= 1 << 0;
 162
 163     // enable counter and pwm, clear reset
 164     obj->pwm->TCR = TCR_CNT_EN | TCR_PWM_EN;
 165 }
 166
 167 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
 168     pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
 169 }
 170
 171 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
 172     pwmout_pulsewidth_us(obj, ms * 1000);
 173 }
 174
 175 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
 176     // calculate number of ticks
 177     uint32_t v = pwm_clock_mhz * us;
 178
 179     // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout
 180     if (v == obj->pwm->MR0) {
 181         v++;
 182     }
 183
 184     // set the match register value
 185     *obj->MR = v;
 186
 187     // set the channel latch to update value at next period start
 188     obj->pwm->LER |= 1 << obj->channel;
 189 }