Class Library for reading hobby servos and detecting invalid or disconnected channels
Dependents: MadPulseCntrl Emaxx_Navigation Emaxx_Navigation_Dynamic_HIL Madpulse_Speed_Control_temp ... more
ServoIn.cpp
00001 // Uses Timer to read servo pulse on single input pin 00002 // J. Bradshaw 20140925 00003 /* Copyright (c) 2015, jbradshaw (http://mbed.org) 00004 * 00005 * Permission is hereby granted, free of charge, to any person obtaining a copy 00006 * of this software and associated documentation files (the "Software"), to deal 00007 * in the Software without restriction, including without limitation the rights 00008 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 00009 * copies of the Software, and to permit persons to whom the Software is 00010 * furnished to do so, subject to the following conditions: 00011 * 00012 * The above copyright notice and this permission notice shall be included in 00013 * all copies or substantial portions of the Software. 00014 * 00015 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 00016 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 00017 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 00018 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 00019 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 00020 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 00021 * THE SOFTWARE. 00022 * 00023 */ 00024 #include "mbed.h" 00025 #include "ServoIn.h" 00026 00027 ServoIn::ServoIn(PinName pin): _interrupt(pin), _pin(pin){ // create the InterruptIn on the pin specified to ServoIn 00028 _interrupt.rise(this, &ServoIn::PulseRead); // attach PulseRead function of this ServoIn instance 00029 00030 _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); // the member function, and interval (15ms) 00031 pulseMeasure.start(); 00032 if(_pin) 00033 _pulseFlag = 1; 00034 else 00035 _pulseFlag = 0; 00036 servoPulse = 0; 00037 servoPulseMax = 2100; 00038 servoPulseMin = 900; 00039 _t_state=0; 00040 } 00041 00042 //function to read the servo pulse duration 00043 void ServoIn::PulseRead() { 00044 if(!_pulseFlag){ //if the flag is low, was waiting for high input interrupt 00045 this->pulseMeasure.reset(); //reset the timer 00046 _interrupt.fall(this, &ServoIn::PulseRead); 00047 _pulseFlag = 1; //set the pulse input flag 00048 } 00049 else{ 00050 servoPulse = pulseMeasure.read_us(); 00051 if(servoPulse < this->servoPulseMax){ 00052 _interrupt.rise(this, &ServoIn::PulseRead); 00053 _pulseFlag = 0; 00054 } 00055 else{ 00056 _pulseFlag = 1; //set the pulse input flag 00057 } 00058 } 00059 _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); //setup interrupt for 15ms 00060 _t_state=0; //re-zero t-state 00061 } 00062 00063 00064 int ServoIn::read(void){ 00065 return servoPulse; 00066 } 00067 00068 float ServoIn::readCalPulse(void){ 00069 servoPulseOffset = ((float)servoPulseMax + (float)servoPulseMin) / 2.0; 00070 servoPulseScale = 1.0 / (((float)servoPulseMax - (float)servoPulseMin) / 2.0); 00071 00072 float pulseCal = ((float)servoPulse-servoPulseOffset)*servoPulseScale; 00073 if((pulseCal > 1.5) || (pulseCal < -1.5)) 00074 return 0.0; 00075 00076 return ((float)servoPulse-servoPulseOffset)*servoPulseScale; 00077 } 00078 00079 void ServoIn::timeoutTest(void){ 00080 if(!_t_state){ 00081 _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); 00082 _t_state=1; //toggle t_sate (15ms has elapsed without servo edge 00083 } 00084 else{ //30 ms has elapsed without a valid servo pulse 00085 _pulseFlag = 0; 00086 _t_state=0; 00087 servoPulse = 0; 00088 _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); 00089 } 00090 } 00091
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