/* * Author: Yevgeniy Kiveisha * Copyright (c) 2014 Intel Corporation. * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include #include #include #include #include "servo.h" using namespace upm; Servo::Servo (int pin) { mraa_result_t error = MRAA_SUCCESS; m_minPulseWidth = MIN_PULSE_WIDTH; m_maxPulseWidth = MAX_PULSE_WIDTH; m_maxPeriod = MAX_PERIOD; m_maxAngle = 180.0; m_servoPin = pin; m_pwmServoContext = mraa_pwm_init (m_servoPin); m_currAngle = 180; setAngle (0); } Servo::~Servo () { mraa_pwm_close (m_pwmServoContext); } /* * X = between (MIN_PULSE_WIDTH , MAX_PULSE_WIDTH) * * X usec * _______ * |_______________________________________ * 20000 usec * * Max period can be only 7968750(nses) which is ~8(msec) * so the servo wil not work as expected. * */ mraa_result_t Servo::setAngle (int angle) { if (m_pwmServoContext == NULL) { std::cout << "PWM context is NULL" << std::endl; return MRAA_ERROR_UNSPECIFIED; } if (angle > m_maxAngle || angle < 0) { return MRAA_ERROR_UNSPECIFIED; } int period = (m_maxPulseWidth - m_minPulseWidth) / m_maxAngle; int cycles = (int)(100.0 * (abs (m_currAngle - angle) / m_maxAngle)); // int cycles = (int)(100.0 * ((float)angle / (float)m_maxAngle)); mraa_pwm_enable (m_pwmServoContext, 1); for (int cycle = 0; cycle < cycles; cycle++) { mraa_pwm_period_us (m_pwmServoContext, m_maxPeriod); mraa_pwm_pulsewidth_us (m_pwmServoContext, calcPulseTraveling(angle)); } mraa_pwm_enable (m_pwmServoContext, 0); std::cout << "angle = " << angle << " ,pulse = " << calcPulseTraveling(angle) << ", cycles " << cycles << std::endl; m_currAngle = angle; } /* * Calculating relative pulse time to the value. * */ int Servo::calcPulseTraveling (int value) { // if bigger than the boundaries if (value > m_maxAngle) { return m_maxPulseWidth; } // if less than the boundaries if (value < 0) { return m_minPulseWidth; } // the conversion return (int) ((float)m_minPulseWidth + ((float)value / m_maxAngle) * ((float)m_maxPulseWidth - (float)m_minPulseWidth)); } void Servo::setMinPulseWidth (int width) { m_minPulseWidth = width; } void Servo::setMaxPulseWidth (int width) { m_maxPulseWidth = width; } void Servo::setMaxPeriod (int width) { m_maxPeriod = width; } int Servo::getMinPulseWidth () { return m_minPulseWidth; } int Servo::getMaxPulseWidth () { return m_maxPulseWidth; } int Servo::getMaxPeriod () { return m_maxPeriod; }