mirror of https://github.com/ArduPilot/ardupilot
194 lines
6.6 KiB
C++
194 lines
6.6 KiB
C++
/*
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APM_RC.cpp - Radio Control Library for Ardupilot Mega. Arduino
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Code by Jordi Muñoz and Jose Julio. DIYDrones.com
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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RC Input : PPM signal on IC4 pin
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RC Output : 11 Servo outputs (standard 20ms frame)
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Methods:
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Init() : Initialization of interrupts an Timers
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OutpuCh(ch,pwm) : Output value to servos (range : 900-2100us) ch=0..10
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InputCh(ch) : Read a channel input value. ch=0..7
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GetState() : Returns the state of the input. 1 => New radio frame to process
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Automatically resets when we call InputCh to read channels
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*/
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#include "APM_RC.h"
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#include <avr/interrupt.h>
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#include "WProgram.h"
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#if !defined(__AVR_ATmega1280__)
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# error Please check the Tools/Board menu to ensure you have selected Arduino Mega as your target.
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#else
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// Variable definition for Input Capture interrupt
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volatile unsigned int ICR4_old;
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volatile unsigned char PPM_Counter=0;
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volatile unsigned int PWM_RAW[8] = {2400,2400,2400,2400,2400,2400,2400,2400};
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volatile unsigned char radio_status=0;
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/****************************************************
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Input Capture Interrupt ICP4 => PPM signal read
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****************************************************/
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ISR(TIMER4_CAPT_vect)
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{
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unsigned int Pulse;
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unsigned int Pulse_Width;
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Pulse=ICR4;
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if (Pulse<ICR4_old) // Take care of the overflow of Timer4 (TOP=40000)
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Pulse_Width=(Pulse + 40000)-ICR4_old; //Calculating pulse
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else
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Pulse_Width=Pulse-ICR4_old; //Calculating pulse
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if (Pulse_Width>8000) // SYNC pulse?
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PPM_Counter=0;
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else
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{
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PPM_Counter &= 0x07; // For safety only (limit PPM_Counter to 7)
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PWM_RAW[PPM_Counter++]=Pulse_Width; //Saving pulse.
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if (PPM_Counter >= NUM_CHANNELS)
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radio_status = 1;
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}
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ICR4_old = Pulse;
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}
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// Constructors ////////////////////////////////////////////////////////////////
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APM_RC_Class::APM_RC_Class()
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{
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}
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// Public Methods //////////////////////////////////////////////////////////////
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void APM_RC_Class::Init(void)
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{
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// Init PWM Timer 1
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pinMode(11,OUTPUT); // (PB5/OC1A)
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pinMode(12,OUTPUT); //OUT2 (PB6/OC1B)
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pinMode(13,OUTPUT); //OUT3 (PB7/OC1C)
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//Remember the registers not declared here remains zero by default...
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TCCR1A =((1<<WGM11)|(1<<COM1A1)|(1<<COM1B1)|(1<<COM1C1)); //Please read page 131 of DataSheet, we are changing the registers settings of WGM11,COM1B1,COM1A1 to 1 thats all...
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TCCR1B = (1<<WGM13)|(1<<WGM12)|(1<<CS11); //Prescaler set to 8, that give us a resolution of 0.5us, read page 134 of data sheet
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OCR1A = 3000; //PB5, none
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OCR1B = 3000; //PB6, OUT2
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OCR1C = 3000; //PB7 OUT3
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ICR1 = 40000; //50hz freq...Datasheet says (system_freq/prescaler)/target frequency. So (16000000hz/8)/50hz=40000,
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// Init PWM Timer 3
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pinMode(2,OUTPUT); //OUT7 (PE4/OC3B)
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pinMode(3,OUTPUT); //OUT6 (PE5/OC3C)
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pinMode(4,OUTPUT); // (PE3/OC3A)
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TCCR3A =((1<<WGM31)|(1<<COM3A1)|(1<<COM3B1)|(1<<COM3C1));
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TCCR3B = (1<<WGM33)|(1<<WGM32)|(1<<CS31);
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OCR3A = 3000; //PE3, NONE
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OCR3B = 3000; //PE4, OUT7
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OCR3C = 3000; //PE5, OUT6
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ICR3 = 40000; //50hz freq
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// Init PWM Timer 5
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pinMode(44,OUTPUT); //OUT1 (PL5/OC5C)
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pinMode(45,OUTPUT); //OUT0 (PL4/OC5B)
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pinMode(46,OUTPUT); // (PL3/OC5A)
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TCCR5A =((1<<WGM51)|(1<<COM5A1)|(1<<COM5B1)|(1<<COM5C1));
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TCCR5B = (1<<WGM53)|(1<<WGM52)|(1<<CS51);
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OCR5A = 3000; //PL3,
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OCR5B = 3000; //PL4, OUT0
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OCR5C = 3000; //PL5, OUT1
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ICR5 = 40000; //50hz freq
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// Init PPM input and PWM Timer 4
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pinMode(49, INPUT); // ICP4 pin (PL0) (PPM input)
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pinMode(7,OUTPUT); //OUT5 (PH4/OC4B)
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pinMode(8,OUTPUT); //OUT4 (PH5/OC4C)
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TCCR4A =((1<<WGM40)|(1<<WGM41)|(1<<COM4C1)|(1<<COM4B1)|(1<<COM4A1));
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//Prescaler set to 8, that give us a resolution of 0.5us
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// Input Capture rising edge
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TCCR4B = ((1<<WGM43)|(1<<WGM42)|(1<<CS41)|(1<<ICES4));
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OCR4A = 40000; ///50hz freq.
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OCR4B = 3000; //PH4, OUT5
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OCR4C = 3000; //PH5, OUT4
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//TCCR4B |=(1<<ICES4); //Changing edge detector (rising edge).
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//TCCR4B &=(~(1<<ICES4)); //Changing edge detector. (falling edge)
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TIMSK4 |= (1<<ICIE4); // Enable Input Capture interrupt. Timer interrupt mask
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}
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void APM_RC_Class::OutputCh(unsigned char ch, int pwm)
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{
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pwm=constrain(pwm,MIN_PULSEWIDTH,MAX_PULSEWIDTH);
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pwm<<=1; // pwm*2;
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switch(ch)
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{
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case 0: OCR5B=pwm; break; //ch0
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case 1: OCR5C=pwm; break; //ch1
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case 2: OCR1B=pwm; break; //ch2
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case 3: OCR1C=pwm; break; //ch3
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case 4: OCR4C=pwm; break; //ch4
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case 5: OCR4B=pwm; break; //ch5
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case 6: OCR3C=pwm; break; //ch6
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case 7: OCR3B=pwm; break; //ch7
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case 8: OCR5A=pwm; break; //ch8, PL3
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case 9: OCR1A=pwm; break; //ch9, PB5
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case 10: OCR3A=pwm; break; //ch10, PE3
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}
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}
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int APM_RC_Class::InputCh(unsigned char ch)
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{
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int result;
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int result2;
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// Because servo pulse variables are 16 bits and the interrupts are running values could be corrupted.
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// We dont want to stop interrupts to read radio channels so we have to do two readings to be sure that the value is correct...
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result = PWM_RAW[ch]>>1; // Because timer runs at 0.5us we need to do value/2
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result2 = PWM_RAW[ch]>>1;
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if (result != result2)
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result = PWM_RAW[ch]>>1; // if the results are different we make a third reading (this should be fine)
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// Limit values to a valid range
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result = constrain(result,MIN_PULSEWIDTH,MAX_PULSEWIDTH);
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radio_status=0; // Radio channel read
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return(result);
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}
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unsigned char APM_RC_Class::GetState(void)
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{
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return(radio_status);
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}
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// InstantPWM implementation
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// This function forces the PWM output (reset PWM) on Out0 and Out1 (Timer5). For quadcopters use
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void APM_RC_Class::Force_Out0_Out1(void)
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{
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if (TCNT5>5000) // We take care that there are not a pulse in the output
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TCNT5=39990; // This forces the PWM output to reset in 5us (10 counts of 0.5us). The counter resets at 40000
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}
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// This function forces the PWM output (reset PWM) on Out2 and Out3 (Timer1). For quadcopters use
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void APM_RC_Class::Force_Out2_Out3(void)
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{
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if (TCNT1>5000)
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TCNT1=39990;
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}
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// This function forces the PWM output (reset PWM) on Out6 and Out7 (Timer3). For quadcopters use
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void APM_RC_Class::Force_Out6_Out7(void)
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{
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if (TCNT3>5000)
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TCNT3=39990;
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}
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// make one instance for the user to use
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APM_RC_Class APM_RC;
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#endif // defined(ATMega1280)
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