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 Class Library
This class library uses external interrupts with timer functions to read servos pulses on mbed input pins.
ServoIn Library usage example
#include "mbed.h" #include "ServoIn.h" DigitalOut led1(LED1); ServoIn servoIn1(p15); ServoIn servoIn2(p14); Serial pc(USBTX, USBRX); // tx, rx int main() { pc.baud(921600); //Fast baud rate while(1) { led1 = 1; wait(0.05); led1 = 0; wait(0.05); pc.printf("servo pulse: CH1=%5dus CH2=%5dus\r\n", servoIn1.read(), servoIn2.read()); } }
ServoIn.cpp@4:379f9ab5cb4b, 2016-08-04 (annotated)
- Committer:
- jebradshaw
- Date:
- Thu Aug 04 15:46:31 2016 +0000
- Revision:
- 4:379f9ab5cb4b
- Parent:
- 3:19c8eaf905e9
- Child:
- 5:598ccee73ed3
Added digital pin and constructor initial state test
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
jebradshaw | 0:98a3b6fbd242 | 1 | // Uses Timer to read servo pulse on single input pin |
jebradshaw | 0:98a3b6fbd242 | 2 | // J. Bradshaw 20140925 |
jebradshaw | 0:98a3b6fbd242 | 3 | /* Copyright (c) 2015, jbradshaw (http://mbed.org) |
jebradshaw | 0:98a3b6fbd242 | 4 | * |
jebradshaw | 0:98a3b6fbd242 | 5 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
jebradshaw | 0:98a3b6fbd242 | 6 | * of this software and associated documentation files (the "Software"), to deal |
jebradshaw | 0:98a3b6fbd242 | 7 | * in the Software without restriction, including without limitation the rights |
jebradshaw | 0:98a3b6fbd242 | 8 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
jebradshaw | 0:98a3b6fbd242 | 9 | * copies of the Software, and to permit persons to whom the Software is |
jebradshaw | 0:98a3b6fbd242 | 10 | * furnished to do so, subject to the following conditions: |
jebradshaw | 0:98a3b6fbd242 | 11 | * |
jebradshaw | 0:98a3b6fbd242 | 12 | * The above copyright notice and this permission notice shall be included in |
jebradshaw | 0:98a3b6fbd242 | 13 | * all copies or substantial portions of the Software. |
jebradshaw | 0:98a3b6fbd242 | 14 | * |
jebradshaw | 0:98a3b6fbd242 | 15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
jebradshaw | 0:98a3b6fbd242 | 16 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
jebradshaw | 0:98a3b6fbd242 | 17 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
jebradshaw | 0:98a3b6fbd242 | 18 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
jebradshaw | 0:98a3b6fbd242 | 19 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
jebradshaw | 0:98a3b6fbd242 | 20 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
jebradshaw | 0:98a3b6fbd242 | 21 | * THE SOFTWARE. |
jebradshaw | 0:98a3b6fbd242 | 22 | * |
jebradshaw | 0:98a3b6fbd242 | 23 | */ |
jebradshaw | 0:98a3b6fbd242 | 24 | #include "mbed.h" |
jebradshaw | 0:98a3b6fbd242 | 25 | #include "ServoIn.h" |
jebradshaw | 0:98a3b6fbd242 | 26 | |
jebradshaw | 4:379f9ab5cb4b | 27 | ServoIn::ServoIn(PinName pin): _interrupt(pin), _pin(pin){ // create the InterruptIn on the pin specified to ServoIn |
jebradshaw | 0:98a3b6fbd242 | 28 | _interrupt.rise(this, &ServoIn::PulseRead); // attach PulseRead function of this ServoIn instance |
jebradshaw | 4:379f9ab5cb4b | 29 | |
jebradshaw | 1:b7cc6da72d09 | 30 | _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); // the member function, and interval (15ms) |
jebradshaw | 0:98a3b6fbd242 | 31 | pulseMeasure.start(); |
jebradshaw | 4:379f9ab5cb4b | 32 | if(_pin) |
jebradshaw | 4:379f9ab5cb4b | 33 | _pulseFlag = 1; |
jebradshaw | 4:379f9ab5cb4b | 34 | else |
jebradshaw | 4:379f9ab5cb4b | 35 | _pulseFlag = 0; |
jebradshaw | 0:98a3b6fbd242 | 36 | servoPulse = 0; |
jebradshaw | 3:19c8eaf905e9 | 37 | servoPulseMax = 2100; |
jebradshaw | 3:19c8eaf905e9 | 38 | servoPulseMin = 900; |
jebradshaw | 3:19c8eaf905e9 | 39 | _t_state=0; |
jebradshaw | 0:98a3b6fbd242 | 40 | } |
jebradshaw | 0:98a3b6fbd242 | 41 | |
jebradshaw | 0:98a3b6fbd242 | 42 | //function to read the servo pulse duration |
jebradshaw | 0:98a3b6fbd242 | 43 | void ServoIn::PulseRead() { |
jebradshaw | 0:98a3b6fbd242 | 44 | if(!_pulseFlag){ //if the flag is low, was waiting for high input interrupt |
jebradshaw | 0:98a3b6fbd242 | 45 | this->pulseMeasure.reset(); //reset the timer |
jebradshaw | 0:98a3b6fbd242 | 46 | _interrupt.fall(this, &ServoIn::PulseRead); |
jebradshaw | 0:98a3b6fbd242 | 47 | _pulseFlag = 1; //set the pulse input flag |
jebradshaw | 0:98a3b6fbd242 | 48 | } |
jebradshaw | 0:98a3b6fbd242 | 49 | else{ |
jebradshaw | 0:98a3b6fbd242 | 50 | servoPulse = pulseMeasure.read_us(); |
jebradshaw | 0:98a3b6fbd242 | 51 | _interrupt.rise(this, &ServoIn::PulseRead); |
jebradshaw | 0:98a3b6fbd242 | 52 | _pulseFlag = 0; |
jebradshaw | 1:b7cc6da72d09 | 53 | } |
jebradshaw | 1:b7cc6da72d09 | 54 | _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); //setup interrupt for 15ms |
jebradshaw | 1:b7cc6da72d09 | 55 | _t_state=0; //re-zero t-state |
jebradshaw | 0:98a3b6fbd242 | 56 | } |
jebradshaw | 0:98a3b6fbd242 | 57 | |
jebradshaw | 0:98a3b6fbd242 | 58 | |
jebradshaw | 0:98a3b6fbd242 | 59 | int ServoIn::read(void){ |
jebradshaw | 0:98a3b6fbd242 | 60 | return servoPulse; |
jebradshaw | 1:b7cc6da72d09 | 61 | } |
jebradshaw | 1:b7cc6da72d09 | 62 | |
jebradshaw | 3:19c8eaf905e9 | 63 | float ServoIn::readCalPulse(void){ |
jebradshaw | 3:19c8eaf905e9 | 64 | servoPulseOffset = ((float)servoPulseMax + (float)servoPulseMin) / 2.0; |
jebradshaw | 3:19c8eaf905e9 | 65 | servoPulseScale = 1.0 / (((float)servoPulseMax - (float)servoPulseMin) / 2.0); |
jebradshaw | 3:19c8eaf905e9 | 66 | |
jebradshaw | 3:19c8eaf905e9 | 67 | float pulseCal = ((float)servoPulse-servoPulseOffset)*servoPulseScale; |
jebradshaw | 3:19c8eaf905e9 | 68 | if((pulseCal > 1.5) || (pulseCal < -1.5)) |
jebradshaw | 3:19c8eaf905e9 | 69 | return 0.0; |
jebradshaw | 3:19c8eaf905e9 | 70 | |
jebradshaw | 3:19c8eaf905e9 | 71 | return ((float)servoPulse-servoPulseOffset)*servoPulseScale; |
jebradshaw | 3:19c8eaf905e9 | 72 | } |
jebradshaw | 3:19c8eaf905e9 | 73 | |
jebradshaw | 1:b7cc6da72d09 | 74 | void ServoIn::timeoutTest(void){ |
jebradshaw | 1:b7cc6da72d09 | 75 | if(!_t_state){ |
jebradshaw | 1:b7cc6da72d09 | 76 | _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); |
jebradshaw | 1:b7cc6da72d09 | 77 | _t_state=1; //toggle t_sate (15ms has elapsed without servo edge |
jebradshaw | 1:b7cc6da72d09 | 78 | } |
jebradshaw | 1:b7cc6da72d09 | 79 | else{ //30 ms has elapsed without a valid servo pulse |
jebradshaw | 1:b7cc6da72d09 | 80 | _pulseFlag = 0; |
jebradshaw | 1:b7cc6da72d09 | 81 | _t_state=0; |
jebradshaw | 1:b7cc6da72d09 | 82 | servoPulse = 0; |
jebradshaw | 1:b7cc6da72d09 | 83 | _validPulseTimeout.attach(this, &ServoIn::timeoutTest, 0.015); |
jebradshaw | 1:b7cc6da72d09 | 84 | } |
jebradshaw | 1:b7cc6da72d09 | 85 | } |
jebradshaw | 1:b7cc6da72d09 | 86 |