mirror of https://github.com/ARMmbed/mbed-os.git
294 lines
7.8 KiB
C
294 lines
7.8 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2006-2013 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "mbed_assert.h"
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#include "pwmout_api.h"
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#include "cmsis.h"
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#include "pinmap.h"
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#include "mbed_error.h"
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static LPC_SCT0_Type *SCTs[4] = {
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(LPC_SCT0_Type*)LPC_SCT0,
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(LPC_SCT0_Type*)LPC_SCT1,
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(LPC_SCT0_Type*)LPC_SCT2,
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(LPC_SCT0_Type*)LPC_SCT3,
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};
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// Pinmap used for testing only
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static const PinMap PinMap_PWM_testing[] = {
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{P0_0, 0, 0},
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{P0_1, 0, 0},
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{P0_2, 0, 0},
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{P0_3, 0, 0},
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{P0_4, 0, 0},
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{P0_5, 0, 0},
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{P0_6, 0, 0},
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{P0_7, 0, 0},
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{P0_8, 0, 0},
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{P0_9, 0, 0},
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{P0_10, 0, 0},
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{P0_11, 0, 0},
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{P0_12, 0, 0},
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{P0_13, 0, 0},
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{P0_14, 0, 0},
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{P0_15, 0, 0},
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{P0_16, 0, 0},
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{P0_17, 0, 0},
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{P0_18, 0, 0},
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{P0_19, 0, 0},
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{P0_20, 0, 0},
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{P0_21, 0, 0},
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{P0_22, 0, 0},
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{P0_23, 0, 0},
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{P0_24, 0, 0},
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{P0_25, 0, 0},
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{P0_26, 0, 0},
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{P0_27, 0, 0},
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{P0_28, 0, 0},
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{P0_29, 0, 0},
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{P0_30, 0, 0},
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{P0_31, 0, 0},
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{P1_0, 0, 0},
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{P1_1, 0, 0},
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{P1_2, 0, 0},
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{P1_3, 0, 0},
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{P1_4, 0, 0},
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{P1_5, 0, 0},
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{P1_6, 0, 0},
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{P1_7, 0, 0},
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{P1_8, 0, 0},
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{P1_9, 0, 0},
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{P1_10, 0, 0},
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{P1_11, 0, 0},
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{P1_12, 0, 0},
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{P1_13, 0, 0},
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{P1_14, 0, 0},
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{P1_15, 0, 0},
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{P1_16, 0, 0},
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{P1_17, 0, 0},
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{P1_18, 0, 0},
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{P1_19, 0, 0},
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{P1_20, 0, 0},
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{P1_21, 0, 0},
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{P1_22, 0, 0},
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{P1_23, 0, 0},
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{P1_24, 0, 0},
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{P1_25, 0, 0},
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{P1_26, 0, 0},
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{P1_27, 0, 0},
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{P1_28, 0, 0},
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{P1_29, 0, 0},
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{P1_30, 0, 0},
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{P1_31, 0, 0},
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{P2_0, 0, 0},
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{P2_1, 0, 0},
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{P2_2, 0, 0},
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{P2_3, 0, 0},
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{P2_4, 0, 0},
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{P2_5, 0, 0},
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{P2_6, 0, 0},
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{P2_7, 0, 0},
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{P2_8, 0, 0},
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{P2_9, 0, 0},
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{P2_10, 0, 0},
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{P2_11, 0, 0},
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{P2_12, 0, 0},
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{NC, NC, 0}
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};
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// bit flags for used SCTs
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static unsigned char sct_used = (1 << 3);
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static int get_available_sct(void) {
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int i;
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for (i=0; i<4; i++) {
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if ((sct_used & (1 << i)) == 0)
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return i;
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}
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return -1;
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}
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void pwmout_init(pwmout_t* obj, PinName pin) {
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MBED_ASSERT(pin != (uint32_t)NC);
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int sct_n = get_available_sct();
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if (sct_n == -1) {
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error("No available SCT");
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}
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sct_used |= (1 << sct_n);
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obj->pwm = SCTs[sct_n];
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obj->pwm_ch = sct_n;
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LPC_SCT0_Type* pwm = obj->pwm;
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// Enable the SCT clock
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LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << (obj->pwm_ch + 2));
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// Clear peripheral reset the SCT:
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LPC_SYSCON->PRESETCTRL1 |= (1 << (obj->pwm_ch + 2));
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LPC_SYSCON->PRESETCTRL1 &= ~(1 << (obj->pwm_ch + 2));
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switch(obj->pwm_ch) {
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case 0:
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// SCT0_OUT0
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LPC_SWM->PINASSIGN[7] &= ~0x0000FF00;
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LPC_SWM->PINASSIGN[7] |= (pin << 8);
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break;
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case 1:
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// SCT1_OUT0
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LPC_SWM->PINASSIGN[8] &= ~0x000000FF;
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LPC_SWM->PINASSIGN[8] |= (pin);
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break;
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case 2:
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// SCT2_OUT0
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LPC_SWM->PINASSIGN[8] &= ~0xFF000000;
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LPC_SWM->PINASSIGN[8] |= (pin << 24);
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break;
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case 3:
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// SCT3_OUT0
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LPC_SWM->PINASSIGN[9] &= ~0x00FF0000;
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LPC_SWM->PINASSIGN[9] |= (pin << 16);
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break;
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default:
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break;
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}
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// Unified 32-bit counter, autolimit
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pwm->CONFIG |= ((0x3 << 17) | 0x01);
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// halt and clear the counter
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pwm->CTRL |= (1 << 2) | (1 << 3);
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pwm->OUT0_SET = (1 << 0); // event 0
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pwm->OUT0_CLR = (1 << 1); // event 1
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// Resolve conflicts on output 0 to set output
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// This allows duty cycle = 1.0 to work, where the MATCH registers for set and clear are equal
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pwm->RES = 0x01;
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pwm->EV0_CTRL = (1 << 12);
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pwm->EV0_STATE = 0xFFFFFFFF;
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pwm->EV1_CTRL = (1 << 12) | (1 << 0);
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pwm->EV1_STATE = 0xFFFFFFFF;
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// default to 20ms: standard for servos, and fine for e.g. brightness control
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pwmout_period_ms(obj, 20);
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pwmout_write (obj, 0);
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}
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void pwmout_free(pwmout_t* obj) {
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// Disable the SCT clock
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LPC_SYSCON->SYSAHBCLKCTRL1 &= ~(1 << (obj->pwm_ch + 2));
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sct_used &= ~(1 << obj->pwm_ch);
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}
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void pwmout_write(pwmout_t* obj, float value) {
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LPC_SCT0_Type* pwm = obj->pwm;
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if (value < 0.0f) {
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value = 0.0;
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} else if (value > 1.0f) {
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value = 1.0;
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}
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uint32_t t_on = (uint32_t)((float)(pwm->MATCHREL0 + 1) * value);
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if (t_on > 0) {
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pwm->MATCHREL1 = t_on - 1;
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// Un-halt the timer and ensure the new pulse-width takes immediate effect if necessary
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if (pwm->CTRL & (1 << 2)) {
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pwm->MATCH1 = pwm->MATCHREL1;
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pwm->CTRL &= ~(1 << 2);
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}
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} else {
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// Halt the timer and force the output low
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pwm->CTRL |= (1 << 2) | (1 << 3);
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pwm->OUTPUT = 0x00000000;
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}
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}
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float pwmout_read(pwmout_t* obj) {
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LPC_SCT0_Type* pwm = obj->pwm;
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uint32_t t_off = pwm->MATCHREL0 + 1;
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uint32_t t_on = (!(pwm->CTRL & (1 << 2))) ? pwm->MATCHREL1 + 1 : 0;
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float v = (float)t_on/(float)t_off;
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return (v > 1.0f) ? (1.0f) : (v);
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}
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void pwmout_period(pwmout_t* obj, float seconds) {
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pwmout_period_us(obj, seconds * 1000000.0f);
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}
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void pwmout_period_ms(pwmout_t* obj, int ms) {
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pwmout_period_us(obj, ms * 1000);
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}
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// Set the PWM period, keeping the duty cycle the same.
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void pwmout_period_us(pwmout_t* obj, int us) {
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LPC_SCT0_Type* pwm = obj->pwm;
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uint32_t t_off = pwm->MATCHREL0 + 1;
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uint32_t t_on = (!(pwm->CTRL & (1 << 2))) ? pwm->MATCHREL1 + 1 : 0;
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float v = (float)t_on/(float)t_off;
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uint32_t period_ticks = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000);
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uint32_t pulsewidth_ticks = period_ticks * v;
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pwm->MATCHREL0 = period_ticks - 1;
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if (pulsewidth_ticks > 0) {
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pwm->MATCHREL1 = pulsewidth_ticks - 1;
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// Un-halt the timer and ensure the new period & pulse-width take immediate effect if necessary
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if (pwm->CTRL & (1 << 2)) {
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pwm->MATCH0 = pwm->MATCHREL0;
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pwm->MATCH1 = pwm->MATCHREL1;
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pwm->CTRL &= ~(1 << 2);
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}
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} else {
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// Halt the timer and force the output low
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pwm->CTRL |= (1 << 2) | (1 << 3);
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pwm->OUTPUT = 0x00000000;
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// Ensure the new period will take immediate effect when the timer is un-halted
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pwm->MATCH0 = pwm->MATCHREL0;
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}
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}
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void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
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pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
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}
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void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
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pwmout_pulsewidth_us(obj, ms * 1000);
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}
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void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
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LPC_SCT0_Type* pwm = obj->pwm;
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if (us > 0) {
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pwm->MATCHREL1 = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000) - 1;
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// Un-halt the timer and ensure the new pulse-width takes immediate effect if necessary
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if (pwm->CTRL & (1 << 2)) {
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pwm->MATCH1 = pwm->MATCHREL1;
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pwm->CTRL &= ~(1 << 2);
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}
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} else {
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// Halt the timer and force the output low
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pwm->CTRL |= (1 << 2) | (1 << 3);
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pwm->OUTPUT = 0x00000000;
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}
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}
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const PinMap *pwmout_pinmap()
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{
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return PinMap_PWM_testing;
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}
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