mbed library sources
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targets/hal/TARGET_NXP/TARGET_LPC15XX/pwmout_api.c
- Committer:
- mbed_official
- Date:
- 2014-07-08
- Revision:
- 250:a49055e7a707
- Parent:
- 234:37acebda271b
- Child:
- 251:de9a1e4ffd79
File content as of revision 250:a49055e7a707:
/* mbed Microcontroller Library * Copyright (c) 2006-2013 ARM Limited * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "mbed_assert.h" #include "pwmout_api.h" #include "cmsis.h" #include "pinmap.h" #include "mbed_error.h" static LPC_SCT0_Type *SCTs[4] = { (LPC_SCT0_Type*)LPC_SCT0, (LPC_SCT0_Type*)LPC_SCT1, (LPC_SCT0_Type*)LPC_SCT2, (LPC_SCT0_Type*)LPC_SCT3, }; // bit flags for used SCTs static unsigned char sct_used = 0; static int get_available_sct(void) { int i; for (i=0; i<4; i++) { if ((sct_used & (1 << i)) == 0) return i; } return -1; } void pwmout_init(pwmout_t* obj, PinName pin) { MBED_ASSERT(pin != (uint32_t)NC); int sct_n = get_available_sct(); if (sct_n == -1) { error("No available SCT"); } sct_used |= (1 << sct_n); obj->pwm = SCTs[sct_n]; obj->pwm_ch = sct_n; LPC_SCT0_Type* pwm = obj->pwm; // Enable the SCT clock LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << (obj->pwm_ch + 2)); // Clear peripheral reset the SCT: LPC_SYSCON->PRESETCTRL1 |= (1 << (obj->pwm_ch + 2)); LPC_SYSCON->PRESETCTRL1 &= ~(1 << (obj->pwm_ch + 2)); switch(obj->pwm_ch) { case 0: // SCT0_OUT0 LPC_SWM->PINASSIGN[7] &= ~0x0000FF00; LPC_SWM->PINASSIGN[7] |= (pin << 8); break; case 1: // SCT1_OUT0 LPC_SWM->PINASSIGN[8] &= ~0x000000FF; LPC_SWM->PINASSIGN[8] |= (pin); break; case 2: // SCT2_OUT0 LPC_SWM->PINASSIGN[8] &= ~0xFF000000; LPC_SWM->PINASSIGN[8] |= (pin << 24); break; case 3: // SCT3_OUT0 LPC_SWM->PINASSIGN[9] &= ~0x00FF0000; LPC_SWM->PINASSIGN[9] |= (pin << 16); break; default: break; } // Two 16-bit counters, autolimit pwm->CONFIG &= ~(0x1); pwm->CONFIG |= (1 << 17); // halt and clear the counter pwm->CTRL |= (1 << 2) | (1 << 3); // System Clock -> us_ticker (1)MHz pwm->CTRL &= ~(0x7F << 5); pwm->CTRL |= (((SystemCoreClock/1000000 - 1) & 0x7F) << 5); // Match reload register pwm->MATCHREL0 = 20000; // 20ms pwm->MATCHREL1 = (pwm->MATCHREL0 / 4); // 50% duty pwm->OUT0_SET = (1 << 0); // event 0 pwm->OUT0_CLR = (1 << 1); // event 1 pwm->EV0_CTRL = (1 << 12); pwm->EV0_STATE = 0xFFFFFFFF; pwm->EV1_CTRL = (1 << 12) | (1 << 0); pwm->EV1_STATE = 0xFFFFFFFF; // unhalt the counter: // - clearing bit 2 of the CTRL register pwm->CTRL &= ~(1 << 2); // default to 20ms: standard for servos, and fine for e.g. brightness control pwmout_period_ms(obj, 20); pwmout_write (obj, 0); } void pwmout_free(pwmout_t* obj) { // Disable the SCT clock LPC_SYSCON->SYSAHBCLKCTRL1 &= ~(1 << (obj->pwm_ch + 2)); sct_used &= ~(1 << obj->pwm_ch); } void pwmout_write(pwmout_t* obj, float value) { LPC_SCT0_Type* pwm = obj->pwm; if (value < 0.0f) { value = 0.0; } else if (value > 1.0f) { value = 1.0; } uint32_t t_on = (uint32_t)((float)(pwm->MATCHREL0) * value); pwm->MATCHREL1 = t_on; } float pwmout_read(pwmout_t* obj) { uint32_t t_off = obj->pwm->MATCHREL0; uint32_t t_on = obj->pwm->MATCHREL1; float v = (float)t_on/(float)t_off; return (v > 1.0f) ? (1.0f) : (v); } void pwmout_period(pwmout_t* obj, float seconds) { pwmout_period_us(obj, seconds * 1000000.0f); } void pwmout_period_ms(pwmout_t* obj, int ms) { pwmout_period_us(obj, ms * 1000); } // Set the PWM period, keeping the duty cycle the same. void pwmout_period_us(pwmout_t* obj, int us) { LPC_SCT0_Type* pwm = obj->pwm; uint32_t t_off = pwm->MATCHREL0; uint32_t t_on = pwm->MATCHREL1; float v = (float)t_on/(float)t_off; pwm->MATCHREL0 = (uint64_t)us; pwm->MATCHREL1 = (uint64_t)((float)us * (float)v); } void pwmout_pulsewidth(pwmout_t* obj, float seconds) { pwmout_pulsewidth_us(obj, seconds * 1000000.0f); } void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) { pwmout_pulsewidth_us(obj, ms * 1000); } void pwmout_pulsewidth_us(pwmout_t* obj, int us) { obj->pwm->MATCHREL1 = (uint64_t)us; }