PIC32MX: Servo Control - Revision history

Andrew Long at 18:44, 9 February 2010

2010-02-09T18:44:07Z

← Older revision		Revision as of 13:44, 9 February 2010
Line 1:		Line 1:
	You can read about [[RC Servo Theory]].		You can read about [[RC Servo Theory]].

			Both of these codes can be used with 5 RC servos. The 20ms period is split into 5 x 4ms sections, 1 for each servo.
			=Servo Control with PWM=
			This example uses the PWM to control 5 RC servos. It only uses 1 timer.

			You can download RCservoSoftPWM.c for the PIC32 [[Media:RCservoSoftPWMPIC32.c \|here]].

			/********************************************************************
			RCServoSoftPWM.c
			This routine is for generating the code signals used to control rotor position
			for up to five little RC servos. An RC servo signal repeats every 20ms:
			High 300 to 2500 uS to indicate rotor position, and then Low. This sample code
			uses the output compare pins OC1 - OC5. It divides the 20ms into 5 x 4ms.
			A 4ms Timer is set up with Timer 2. The interrupt determines which pin to turn on
			at the given duty cycle. The other PWMs are set to zero duty cycle (off).

			Andrew Long
			Northwestern University
			2-2010

			********************************************************************/

			/ INCLUDES *****************************************************/
			#include <plib.h>
			#include "HardwareProfile.h"

			#define MIN_SERVO_DUTY 3000
			#define MAX_SERVO_DUTY 25000

			int RCservo[5]; // Desired high durations here 3000 - 25000 values give 0.3 mS
			// to 2.5 mS.
			int RCcount;

			int main(void)
			{
			// Configure the proper PB frequency and the number of wait states
			SYSTEMConfigPerformance(SYS_FREQ);

			INTEnableSystemMultiVectoredInt();

			// init the output compare modules
			// comment out the servos you do not want to use
			OpenOC1( OC_ON \| OC_TIMER2_SRC \| OC_PWM_FAULT_PIN_DISABLE, 0, 0);
			OpenOC2( OC_ON \| OC_TIMER2_SRC \| OC_PWM_FAULT_PIN_DISABLE, 0, 0);
			OpenOC3( OC_ON \| OC_TIMER2_SRC \| OC_PWM_FAULT_PIN_DISABLE, 0, 0);
			OpenOC4( OC_ON \| OC_TIMER2_SRC \| OC_PWM_FAULT_PIN_DISABLE, 0, 0);
			OpenOC5( OC_ON \| OC_TIMER2_SRC \| OC_PWM_FAULT_PIN_DISABLE, 0, 0);

			// init Timer2 mode and period (PR2)
			// Fpb = SYS_FREQ = 80Mhz (From configuration in bootloader code)
			// Timer Prescale = 8
			// PR2 = 0x9C3F = 39,999
			// interrupts every 4 ms
			// 4 ms = (PR2 + 1) * TMR Prescale / Fpb = (39999 + 1) * 8 / 80000000
			CloseTimer2();
			OpenTimer2( T2_ON \| T2_PS_1_8 \| T2_SOURCE_INT, 0x9C3F);
			ConfigIntTimer2(T2_INT_ON \| T2_INT_PRIOR_7);

			mT2SetIntPriority( 7); // set Timer2 Interrupt Priority
			mT2ClearIntFlag(); // clear interrupt flag
			mT2IntEnable(1); // enable timer2 interrupts

			int counter;
			while(1)
			{
			// This code ramps up each servo then starts over
			for (RCservo[0] = MIN_SERVO_DUTY; RCservo[0] < MAX_SERVO_DUTY; RCservo[0]+=1)
			{
			int i;
			for (i = 1; i < 5; i++)
			{
			RCservo[i] = RCservo[i-1] + 200;
			if (RCservo[i] > MAX_SERVO_DUTY) RCservo[i] -= MAX_SERVO_DUTY - MIN_SERVO_DUTY;

			//Put in short pause
			counter = 500;
			while(counter-- != 0);
			}
			}

			}
			CloseTimer2();
			CloseOC1();
			CloseOC2();
			CloseOC3();
			CloseOC4();
			CloseOC5();

			} //end main

			void __ISR( _TIMER_2_VECTOR, ipl7) T2Interrupt( void)
			{
			if (++RCcount >= 5) RCcount = 0; // 20mS cycle --> 5 interrupts

			// Set all PWM pins low -- comment out the pins you do not want
			SetDCOC1PWM(0);
			SetDCOC2PWM(0);
			SetDCOC3PWM(0);
			SetDCOC4PWM(0);
			SetDCOC5PWM(0);

			// Determine selected servo and set PWM
			switch(RCcount)
			{
			case 0: // comment out the pins you do not want
			SetDCOC1PWM(RCservo[RCcount]);
			break;
			case 1:
			SetDCOC2PWM(RCservo[RCcount]);
			break;
			case 2:
			SetDCOC3PWM(RCservo[RCcount]);
			break;
			case 3:
			SetDCOC4PWM(RCservo[RCcount]);
			break;
			case 4:
			SetDCOC5PWM(RCservo[RCcount]);
			break;
			}

			// clear interrupt flag and exit
			mT2ClearIntFlag();
			} // T2 Interrupt



	=Servo Control with Digital Output=		=Servo Control with Digital Output=

Andrew Long: /* Servo Control with Digital Output */

2010-02-09T18:39:34Z

Servo Control with Digital Output

← Older revision		Revision as of 13:39, 9 February 2010
Line 4:		Line 4:

	This example is based on the code from PIC18. It uses two timers and up to 5 digital outputs. The PWM pins can be saved for other motor controls.		This example is based on the code from PIC18. It uses two timers and up to 5 digital outputs. The PWM pins can be saved for other motor controls.

		⚫	You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.c \|here]].

	/********************************************************************		/********************************************************************
Line 139:		Line 141:
	mT3ClearIntFlag();		mT3ClearIntFlag();
	}		}


⚫	You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.c \|here]].

Andrew Long at 18:38, 9 February 2010

2010-02-09T18:38:30Z

← Older revision		Revision as of 13:38, 9 February 2010
Line 1:		Line 1:
	You can read about [[RC Servo Theory]].		You can read about [[RC Servo Theory]].

			=Servo Control with Digital Output=
	= Digital Output Example =

	This example is based on the code from PIC18. It uses two timers and up to 5 digital outputs. The PWM pins can be saved for other motor controls.		This example is based on the code from PIC18. It uses two timers and up to 5 digital outputs. The PWM pins can be saved for other motor controls.

Andrew Long: /* Digital Output Example */

2010-02-09T18:38:10Z

Digital Output Example

← Older revision		Revision as of 13:38, 9 February 2010
Line 94:		Line 94:
	{		{
	if (++RCcount >= 20) RCcount = 0; // 20mS cycle --> 20 interrupts		if (++RCcount >= 20) RCcount = 0; // 20mS cycle --> 20 interrupts


	if ((RCcount & 3) == 0) // on the 4mS boundaries turn all the pins low		if ((RCcount & 3) == 0) // on the 4mS boundaries turn all the pins low
	{		{

Andrew Long: /* Digital Output Example */

2010-02-09T18:37:45Z

Digital Output Example

← Older revision		Revision as of 13:37, 9 February 2010
Line 25:		Line 25:
	/ INCLUDES *****************************************************/		/ INCLUDES *****************************************************/
	#include "HardwareProfile.h"		#include "HardwareProfile.h"


	#define LOW 0		#define LOW 0
	#define HIGH 1		#define HIGH 1

Andrew Long: /* Digital Output Example */

2010-02-09T18:37:37Z

Digital Output Example

← Older revision		Revision as of 13:37, 9 February 2010
Line 20:		Line 20:
	1mS ISR, put it after this RC servo code, so as not to disturb our timing.		1mS ISR, put it after this RC servo code, so as not to disturb our timing.
	This code has been generated with reference to RCservoSoft.c from m.peshkin.		This code has been generated with reference to RCservoSoft.c from m.peshkin.

⚫	********************************************************************/

		⚫	********************************************************************/

	/ INCLUDES *****************************************************/		/ INCLUDES *****************************************************/
	#include "HardwareProfile.h"		#include "HardwareProfile.h"

Andrew Long at 18:37, 9 February 2010

2010-02-09T18:37:29Z

← Older revision		Revision as of 13:37, 9 February 2010
Line 1:		Line 1:
	You can read about [[RC Servo Theory]].		You can read about [[RC Servo Theory]].

			= Digital Output Example =
	You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.zip \|here]].

			This example is based on the code from PIC18. It uses two timers and up to 5 digital outputs. The PWM pins can be saved for other motor controls.

			/********************************************************************
			RCServoSoft.c a.long 2009-09-11
			This routine is for generating the code signals used to control rotor position
			for up to five little RC servos. An RC servo signal repeats every 20ms:
			High 300 to 2500 uS to indicate rotor position, and then Low. This sample code
			uses pins RD0 - RD4 but you can switch it to whichever pins (and as few) as you wish.
			This routine uses Timer 3 to generate the RC servo signals in semi-software.
			Timer2 and Timer3 can be used for hardware PWM, so you may be interested in changing
			the timer.

			We'll keep a 1KHz interrupt routine going with Timer2. This ISR sets all outputs
			low every 4mS. Using a Timer 3 ISR, we turn one of the five outputs high,
			every 300-2500 uS prior to the next 4mS boundary. If you have other stuff in the
			1mS ISR, put it after this RC servo code, so as not to disturb our timing.
			This code has been generated with reference to RCservoSoft.c from m.peshkin.

			********************************************************************/

			/ INCLUDES *****************************************************/
			#include "HardwareProfile.h"

			#define LOW 0
			#define HIGH 1

			// Define PIN_DX for output
			#define PIN_D0 LATDbits.LATD0
			#define PIN_D1 LATDbits.LATD1
			#define PIN_D2 LATDbits.LATD2
			#define PIN_D3 LATDbits.LATD3
			#define PIN_D4 LATDbits.LATD4

			int RCservo[5]; // Desired high durations here 375-3125 values give 0.3 mS
			// to 2.5 mS.
			int RCcount;
			int OneMStimer;

			int main(void)
			{
			int i;

			// Configure the proper PB frequency and the number of wait states
			SYSTEMConfigPerformance(SYS_FREQ);

			INTEnableSystemMultiVectoredInt();

			// Set PINS D0 - D4 as digital outputs
			LATD \|= 0x001F; TRISD &= 0xFFE0;

			// init Timer2 mode and period (PR2)
			// Fpb = SYS_FREQ = 80Mhz (From configuration in bootloader code)
			// Timer Prescale = 2
			// PR2 = 0x9C3F = 39,999
			// interrupts every 1 ms
			// 1 ms = (PR2 + 1) * TMR Prescale / Fpb = (39999 + 1) * 2 / 80000000
			CloseTimer2();
			OpenTimer2( T2_ON \| T2_PS_1_2 \| T2_SOURCE_INT, 0x9C3F);
			ConfigIntTimer2(T2_INT_ON \| T2_INT_PRIOR_5);

			// init Timer3 mode and period (PR3)
			// Fpb = SYS_FREQ = 80Mhz (From configuration in bootloader code)
			// Timer Prescale = 64
			// PR3 = 0xFFFF = 65535
			// Ticks every 0.8 uS = TMR Prescale / Fpb = 64 / 80000000
			CloseTimer3();
			OpenTimer3( T3_ON \| T3_PS_1_64 \| T3_SOURCE_INT, 0xFFFF);
			ConfigIntTimer3(T3_INT_ON \| T3_INT_PRIOR_6);

			while(1) // demo routine moves all five through their range of duty cycles
			{
			for (RCservo[0] = 375; RCservo[0] < 3125; RCservo[0]+=1)
			{
			for (i = 1; i < 5; i++)
			{
			RCservo[i] = RCservo[i-1] + 200;
			if (RCservo[i] > 3125) RCservo[i] -= 2750;
			}
			OneMStimer = 1;
			while(OneMStimer); // sweep slowly through available duty cycles
			// uses the 1 ms interrupt of Timer 2
			}
			}
			CloseTimer2();
			CloseTimer3();
			} //end main


			void __ISR(_TIMER_2_VECTOR,ipl5)Timer2Handler(void)
			{
			if (++RCcount >= 20) RCcount = 0; // 20mS cycle --> 20 interrupts

			if ((RCcount & 3) == 0) // on the 4mS boundaries turn all the pins low
			{
			PIN_D0 = LOW;
			PIN_D1 = LOW;
			PIN_D2 = LOW;
			PIN_D3 = LOW;
			PIN_D4 = LOW;

			WriteTimer3(60536 + RCservo[RCcount>>2]); // yes 60536, not 65536.
			// Go high 4000uS (5000 * 0.8uS) from now,
			// and sooner due to desired High period
			}

			// your ISR stuff goes here, after the RC part, so as not to disrupt the timing
			--OneMStimer;
			// clear interrupt flag and exit
			mT2ClearIntFlag();
			}

			void __ISR(_TIMER_3_VECTOR, ipl6)Timer3Handler(void) // this ISR is called when Timer 3
			// times out, to set one of the RC
			// servo output pins high
			{
			switch(RCcount>>2)
			{
			case 0: // comment out the pins you do not want
			PIN_D0 = HIGH;
			break;
			case 1:
			PIN_D1 = HIGH;
			break;
			case 2:
			PIN_D2 = HIGH;
			break;
			case 3:
			PIN_D3 = HIGH;
			break;
			case 4:
			PIN_D4 = HIGH;
			break;
			}
			// clear interrupt flag and exit
			mT3ClearIntFlag();
			}


			You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.c \|here]].

Andrew Long at 15:21, 28 August 2009

2009-08-28T15:21:21Z

← Older revision		Revision as of 10:21, 28 August 2009
Line 1:		Line 1:
	You can read about [[RC Servo Theory]].		You can read about [[RC Servo Theory]].

	You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.c \|here]].		You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.zip \|here]].

Andrew Long: New page: You can read about RC Servo Theory. You can download RCservoSoft.c for the PIC32 here.

2009-08-28T15:20:34Z

New page: You can read about RC Servo Theory. You can download RCservoSoft.c for the PIC32 here.

New page

You can read about [[RC Servo Theory]].

You can download RCservoSoft.c for the PIC32 [[Media:RCservoSoftPIC32.c |here]].