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| 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 | + |
| 17 | +#include "pwmout_api.h" |
| 18 | +#include "cmsis.h" |
| 19 | +#include "pinmap.h" |
| 20 | +#include "error.h" |
| 21 | + |
| 22 | +#if DEVICE_PWMOUT |
| 23 | + |
| 24 | +#define SCT_CHANNELS 2 |
| 25 | + |
| 26 | +static const PinMap PinMap_PWM[] = { |
| 27 | + {P1_19, SCT0_0, 2}, |
| 28 | + {P2_2 , SCT0_1, 3}, |
| 29 | + {P2_7 , SCT0_2, 2}, |
| 30 | + {P1_13, SCT0_3, 2}, |
| 31 | + {P2_16, SCT1_0, 1}, |
| 32 | + {P2_17, SCT1_1, 1}, |
| 33 | + {P2_18, SCT1_2, 1}, |
| 34 | + {P2_19, SCT1_3, 1}, |
| 35 | + {NC , NC ,0} |
| 36 | +}; |
| 37 | + |
| 38 | + |
| 39 | +static LPC_SCT0_Type *SCTs[SCT_CHANNELS] = { |
| 40 | + (LPC_SCT0_Type*)LPC_SCT0, |
| 41 | + (LPC_SCT0_Type*)LPC_SCT1, |
| 42 | + |
| 43 | +}; |
| 44 | + |
| 45 | +// bit flags for used SCTs |
| 46 | +static unsigned char sct_used = 0; |
| 47 | + |
| 48 | +static int get_available_sct(void) { |
| 49 | + int i; |
| 50 | + for (i=0; i<SCT_CHANNELS; i++) { |
| 51 | + if ((sct_used & (1 << i)) == 0) |
| 52 | + return i; |
| 53 | + } |
| 54 | + return -1; |
| 55 | +} |
| 56 | + |
| 57 | +void pwmout_init(pwmout_t* obj, PinName pin) { |
| 58 | + // determine the SPI to use |
| 59 | + PWMName pwm_mapped = (PWMName)pinmap_peripheral(pin, PinMap_PWM); |
| 60 | + if (pwm_mapped == (uint32_t)NC) { |
| 61 | + error("PwmOut pin mapping failed"); |
| 62 | + } |
| 63 | + int sct_n = get_available_sct(); |
| 64 | + if (sct_n == -1) { |
| 65 | + error("No available SCT"); |
| 66 | + } |
| 67 | + |
| 68 | + sct_used |= (1 << sct_n); |
| 69 | + obj->pwm = SCTs[sct_n]; |
| 70 | + obj->pwm_ch = sct_n; |
| 71 | + |
| 72 | + // Enable the SCT clock |
| 73 | + LPC_SYSCON->SYSAHBCLKCTRL |= (1UL << 31); |
| 74 | + |
| 75 | + // Clear peripheral reset the SCT: |
| 76 | + LPC_SYSCON->PRESETCTRL |= (1 << (obj->pwm_ch + 9)); |
| 77 | + pinmap_pinout(pin, PinMap_PWM); |
| 78 | + LPC_SCT0_Type* pwm = obj->pwm; |
| 79 | + |
| 80 | + // Two 16-bit counters, autolimit |
| 81 | + pwm->CONFIG &= ~(0x1); |
| 82 | + pwm->CONFIG |= (1 << 17); |
| 83 | + |
| 84 | + // halt and clear the counter |
| 85 | + pwm->CTRL |= (1 << 2) | (1 << 3); |
| 86 | + |
| 87 | + // System Clock -> us_ticker (1)MHz |
| 88 | + pwm->CTRL &= ~(0x7F << 5); |
| 89 | + pwm->CTRL |= (((SystemCoreClock/1000000 - 1) & 0x7F) << 5); |
| 90 | + |
| 91 | + switch(pwm_mapped) { |
| 92 | + case SCT0_0: |
| 93 | + case SCT1_0: |
| 94 | + pwm->OUT0_SET = (1 << 0); // event 0 |
| 95 | + pwm->OUT0_CLR = (1 << 1); // event 1 |
| 96 | + break; |
| 97 | + case SCT0_1: |
| 98 | + case SCT1_1: |
| 99 | + pwm->OUT1_SET = (1 << 0); // event 0 |
| 100 | + pwm->OUT1_CLR = (1 << 1); // event 1 |
| 101 | + break; |
| 102 | + case SCT0_2: |
| 103 | + case SCT1_2: |
| 104 | + pwm->OUT2_SET = (1 << 0); // event 0 |
| 105 | + pwm->OUT2_CLR = (1 << 1); // event 1 |
| 106 | + break; |
| 107 | + case SCT0_3: |
| 108 | + case SCT1_3: |
| 109 | + pwm->OUT3_SET = (1 << 0); // event 0 |
| 110 | + pwm->OUT3_CLR = (1 << 1); // event 1 |
| 111 | + break; |
| 112 | + default: |
| 113 | + break; |
| 114 | + } |
| 115 | + // Event 0 : MATCH and MATCHSEL=0 |
| 116 | + pwm->EV0_CTRL = (1 << 12); |
| 117 | + pwm->EV0_STATE = 0xFFFFFFFF; |
| 118 | + // Event 1 : MATCH and MATCHSEL=1 |
| 119 | + pwm->EV1_CTRL = (1 << 12) | (1 << 0); |
| 120 | + pwm->EV1_STATE = 0xFFFFFFFF; |
| 121 | + |
| 122 | + // Match reload register |
| 123 | + pwm->MATCHREL0 = 20000; // 20ms |
| 124 | + pwm->MATCHREL1 = (pwm->MATCHREL0 / 4); // 50% duty |
| 125 | + |
| 126 | + // unhalt the counter: |
| 127 | + // - clearing bit 2 of the CTRL register |
| 128 | + pwm->CTRL &= ~(1 << 2); |
| 129 | + |
| 130 | + // default to 20ms: standard for servos, and fine for e.g. brightness control |
| 131 | + pwmout_period_ms(obj, 20); |
| 132 | + pwmout_write (obj, 0); |
| 133 | +} |
| 134 | + |
| 135 | +void pwmout_free(pwmout_t* obj) { |
| 136 | + sct_used &= ~(1 << obj->pwm_ch); |
| 137 | + if (sct_used == 0) { |
| 138 | + // Disable the SCT clock |
| 139 | + LPC_SYSCON->SYSAHBCLKCTRL &= ~(1UL << 31); |
| 140 | + } |
| 141 | +} |
| 142 | + |
| 143 | +void pwmout_write(pwmout_t* obj, float value) { |
| 144 | + if (value < 0.0f) { |
| 145 | + value = 0.0; |
| 146 | + } else if (value > 1.0f) { |
| 147 | + value = 1.0; |
| 148 | + } |
| 149 | + uint32_t t_off = obj->pwm->MATCHREL0 - (uint32_t)((float)(obj->pwm->MATCHREL0) * value); |
| 150 | + uint32_t t_on = (uint32_t)((float)(obj->pwm->MATCHREL0) * value); |
| 151 | + obj->pwm->MATCHREL1 = t_on; |
| 152 | +} |
| 153 | + |
| 154 | +float pwmout_read(pwmout_t* obj) { |
| 155 | + uint32_t t_off = obj->pwm->MATCHREL0; |
| 156 | + uint32_t t_on = obj->pwm->MATCHREL1; |
| 157 | + float v = (float)t_on/(float)t_off; |
| 158 | + return (v > 1.0f) ? (1.0f) : (v); |
| 159 | +} |
| 160 | + |
| 161 | +void pwmout_period(pwmout_t* obj, float seconds) { |
| 162 | + pwmout_period_us(obj, seconds * 1000000.0f); |
| 163 | +} |
| 164 | + |
| 165 | +void pwmout_period_ms(pwmout_t* obj, int ms) { |
| 166 | + pwmout_period_us(obj, ms * 1000); |
| 167 | +} |
| 168 | + |
| 169 | +// Set the PWM period, keeping the duty cycle the same. |
| 170 | +void pwmout_period_us(pwmout_t* obj, int us) { |
| 171 | + uint32_t t_off = obj->pwm->MATCHREL0; |
| 172 | + uint32_t t_on = obj->pwm->MATCHREL1; |
| 173 | + float v = (float)t_on/(float)t_off; |
| 174 | + obj->pwm->MATCHREL0 = (uint64_t)us; |
| 175 | + obj->pwm->MATCHREL1 = (uint64_t)((float)us * (float)v); |
| 176 | +} |
| 177 | + |
| 178 | +void pwmout_pulsewidth(pwmout_t* obj, float seconds) { |
| 179 | + pwmout_pulsewidth_us(obj, seconds * 1000000.0f); |
| 180 | +} |
| 181 | + |
| 182 | +void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) { |
| 183 | + pwmout_pulsewidth_us(obj, ms * 1000); |
| 184 | +} |
| 185 | + |
| 186 | +void pwmout_pulsewidth_us(pwmout_t* obj, int us) { |
| 187 | + obj->pwm->MATCHREL1 = (uint64_t)us; |
| 188 | +} |
| 189 | + |
| 190 | +#endif |
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