AN957

AN957
Sensored BLDC Motor Control Using dsPIC30F2010
Author:
Stan D’Souza
Microchip Technology
INTRODUCTION
The dsPIC30F2010 is a 28-pin 16-bit MCU specifically
designed for embedded motor control applications. AC
Induction Motors (ACIM), Brushless DC (BLDC) and
DC are some typical motor types for which the
dsPIC30F2010 has been specifically designed. Some
of the key features on the dsPIC30F2010 are:
• 6 independent or 3 complementary pairs of
dedicated Motor Control PWM outputs.
• 6 input, 500Ksps ADC with up to 4 simultaneous
sampling capability.
• Multiple serial communications: UART, I2C™ and
SPI
• Small package: 6 x 6 mm QFN for embedded
control applications
• DSP engine for fast response in control loops.
In this application note we discuss how the
dsPIC30F2010 is used to control a sensored BLDC
motor. Please refer to AN901 for details on how BLDC
motors operate and general information on what needs
to be done to run and control BLDC motors. This
application note discusses the specific implementation
using the dsPIC30F2010. It touches only briefly on
BLDC motor details
BLDC MOTORS
BLDC motors are basically inside-out DC motors. In a
DC motor the stator is a permanent magnet. The rotor
has the windings, which are excited with a current. The
current in the rotor is reversed to create a rotating or
moving electric field by means of a split commutator
and brushes. On the other hand, in a BLDC motor the
windings are on the stator and the rotor is a permanent
magnet. Hence the term inside-out DC motor.
To make the rotor turn, there must be a rotating electric
field. Typically a three-phase BLDC motor has three
stator phases that are excited two at a time to create a
rotating electric field. This method is fairly easy to
implement, but to prevent the permanent magnet rotor
from getting locked with the stator, the excitation on the
stator must be sequenced in a specific manner while
knowing the exact position of the rotor magnets.
Position information can be gotten by either a shaft
 2004 Microchip Technology Inc.
encoder or, more often, by Hall effect sensors that
detect the rotor magnet position. For a typical threephase, sensored BLDC motor there are six distinct
regions or sectors in which two specific windings are
excited. These are as shown in Figure 1.
FIGURE 1:
HALL R
BLDC COMMUTATION
DIAGRAM
60o
HALL Y
HALL B
FIRING Q3,Q5Q1,Q5Q1,Q6Q2,Q6Q2,Q4Q3,Q4Q3,Q5Q1,Q5Q1,Q6
HALL STATE 5
4
6
2
3
1
5
4
6
RYB
By reading the Hall effect sensors, a 3-bit code can be
obtained with values ranging from 1 to 6. Each code
value represents a sector on which the rotor is
presently located. Each code value, therefore, gives us
information on which windings need to be excited. Thus
a simple lookup table can be used by the program to
determine which two specific windings to excite and,
thus, turn the rotor.
Note that state ‘0’ and ‘7’ are invalid states for Hall
effect sensors. Software should check for these values
and appropriately disable the PWM.
Change Notification Inputs
Taking this technique a step further, the Hall effect
sensors can be connected to dsPIC30F2010 inputs
that detect a change (Change Notification (CN) inputs).
An input change on these pins generates an interrupt.
In the CN Interrupt Service Routine (ISR) the user
application program reads the Hall effect sensor value
and uses it to generate an offset in the lookup table for
driving the windings of the BLDC motor.
DS00957A-page 1
AN957
MOTOR CONTROL PULSE WIDTH
MODULATION (MCPWM)
Using the above method, you can get full speed
rotation of the BLDC motor. However, to get variable
speed of the BLDC motor, you must apply a variable
voltage to the terminals of the windings. Putting this in
digital terms, the variable voltage can be obtained by
different duty cycles of a PWM signal going to the
windings of the BLDC motor.
The dsPIC30F2010 has six PWM outputs that can be
driven with the PWM signal. As shown in Figure 2, the
three windings can be driven ON High, driven ON Low
or not driven at all by using six switches, IGBTs or
MOSFETs. When one leg of the winding is connected
for example, to the high side, the variable duty cycle
signal PWM can be injected on the low side driver. This
has the same effect as having a PWM signal on the
high side and connecting the low side to VSS or GND.
When driving the PWM signal, low side drivers are
preferred over high side drivers.
FIGURE 2:
BEMF SENSING
HARDWARE EXAMPLE
z
=
Q1
Q3
B
R
VDC
z
PWM is provided by the dsPIC30F2010’s dedicated
Motor Control (MC) PWM. The MCPWM module has
been designed specifically for motor control
applications. (Please refer to Figure 3 as you follow this
discussion of the MCPWM module.)
The MCPWM has a dedicated 16-bit PTMR time base
register. This timer is incremented by a user defined
clock tick, which can be as low as TCY. The user also
decides the period required for the PWM by selecting a
value and loading it in the PTPER registers. The PTMR
is compared to the PTPER value at every TCY. When
there is a match, a new period is started.
The duty cycle is controlled similarly, by loading a value
in the three duty cycle registers. Unlike the period compare, the value in the duty cycle register is compared at
every TCY/2 interval (i.e., twice as fast as the period
compare). If there is a match between the PTMR value
and the PDCx value, then the corresponding duty cycle
output is driven low or high as dictated by the PWM
mode selected. The three outputs from the duty cycle
compare are channeled to a complementary output
pair where one output is high while the other is low, and
vice versa. The two outputs can also be configured as
independent outputs. When driven as complementary
outputs, a dead time can be inserted between the time
the high level goes low and the low level goes high.
This dead time is hardware configured and has a
minimum value of TCY. Dead time insertion prevents
inadvertent shoot-thru in output drivers.
z
Q4
z
Q6
Y
DS00957A-page 2
 2004 Microchip Technology Inc.
AN957
FIGURE 3:
PWM BLOCK DIAGRAM
PWMCON1
PWM Enable and Mode SFRs
PWMCON2
DTCON1
Dead Time Control SFR
FLTACON
FLTA Pin Control SFR
OVDCON
PWM Manual
Control SFR
PWM Generator #3
16-bit Data Bus
PDC3 Buffer
PDC3
Comparator
PWM Generator
#2
PTMR
PWM3H
Channel 3 Dead Time
Generator and
Override Logic
Channel 2 Dead Time
Generator and
Override Logic
PWM3L
Output
Driver
Block
PWM2H
PWM2L
Comparator
PWM Generator
#1
PTPER
Channel 1 Dead Time
Generator and
Override Logic
PWM1H
PWM1L
FLTA
PTPER Buffer
PTCON
Comparator
SEVTDIR
SEVTCMP
Special Event
Postscaler
Special Event Trigger
PTDIR
PWM time base
Note: Details of PWM Generator #1 and #2 not shown for clarity.
 2004 Microchip Technology Inc.
DS00957A-page 3
AN957
There are several modes in which the MCPWM module
can be configured. Edge aligned output is probably the
most common mode. Figure 4 depicts the operation of
an edge aligned PWM. At the start of the period, the
outputs are all driven high. As the PTMR increments, a
match with the duty cycle registers causes the corresponding duty cycle output to go low thereby marking
the end of the duty cycle. The PTMR match with
PTPER register caused a new period to start and all
outputs go high to start a whole new cycle.
FIGURE 4:
EDGE-ALIGNED PWM
New duty cycle loaded from PDCx
Depending on the value in the OVDCON register, the
user can select which pin gets the PWM signal and
which pin is driven active or inactive. When controlling
the BLDC sensored motor it is necessary to excite two
winding pairs depending on where the rotor is located
and dictated by the value of the hall sensors. In the CN
Interrupt Service routine the hall sensors are read and
then the value of the sensors is used as an offset in a
lookup table which corresponds to the value which will
be loaded in the OVDCON register. Table 1 and
Figure 5 show how different values are loaded in the
OVDCON register depending on which sector the rotor
is located in and thereby which windings need to be
excited.
TABLE 1:
PTPER
PDC1
PDC2
PTMR value
0
PWM1H
PWM OUTPUT OVERRIDE
EXAMPLE
State
OVDCON<15:8>
OVDCON<7:0>
1
2
3
4
00000011b
00110000b
00111100b
00001111b
00000000b
00000000b
00000000b
00000000b
Duty Cycle
FIGURE 5:
PWM2H
PWM OUTPUT OVERRIDE
EXAMPLE
Period
STATE
1
The other modes that the MCPWM can be set up for
are center-aligned PWM and single-shot PWM. These
modes are not discussed here because they were not
used for controlling the BLDC motor. For details on
these modes, please refer to the dsPIC30F Family
Reference Manual (DS70046).
The important feature of the MCPWM used in this
application is the Override Control. The Override
Control is the last stage of the MCPWM module. It
allows the user to directly write to the OVDCON
register and control the output pins. The OVDCON register has two 6 bit fields in it. Each of the six bit fields
corresponds to an output pin. The high byte portion of
the OVDCON register, determines if the corresponding
output pin is driven by a PWM signal (when set to 1) or
(when set to 0) driven Active/Inactive by the corresponding bit field in the low byte portion of the
OVDCON register. This feature allows the user to have
PWM signals available, but not driving, at all output
stages of the pins. For BLDC motors, the same value is
written to all PDCx registers.
DS00957A-page 4
2
3
4
PWM3H
PWM3L
PWM2H
PWM2L
PWM1H
PWM1L
Note:
Switching times between states 1-4 are controlled
by user software. The state switch is controlled by
writing a new value to OVDCON. The PWM
outputs are operated in the independent mode for
this example.
 2004 Microchip Technology Inc.
AN957
HARDWARE DESCRIPTION
FIRMWARE DESCRIPTION
The block diagram in Figure 6 depicts how the BLDC
motor is driven using a dsPIC30F2010. For a detailed
schematic please refer to Appendix C.
Two firmware programs are included in Appendix A
and Appendix B to illustrate the methods described in
the Application Note. One program uses open-loop
speed control. The other uses proportional and integral
feedback for closed loop speed control.
FIGURE 6:
HARDWARE BLOCK
DIAGRAM
dsPIC30F2010
BLDC
PWM3H
PWM3L
PWM2H
PWM2L
PWM1H
PWM1L
MOSFET
Drive
Circuit
AN2
Demand
CN5
CN6
CN7
Hall Effect Sensor Feedback
The six MCPWM outputs are connected to three
MOSFET driver pairs (IR2101S), which in turn are
connected to six MOSFETs (IRFR2407). These
MOSFETs are connected in a three-phase bridge
format to the three BLDC motor windings. In the current
implementation, the maximum MOSFET voltage is 70
Volts, and the maximum MOSFET current is 18 Amps.
It is important to note that adequate heat dissipation
must be provided if the maximum capabilities are being
used. MOSFET drivers also require a higher voltage
(15V) to operate, so this voltage level needs to be provided. The motor is a 24V BLDC motor so the DC+ to
DC- bus voltage is 24V. A regulated 5V is provided to
drive the dsPIC30F2010. The three Hall effect sensor
inputs are connected to input pins that have Change
Notification circuits associated with them. These inputs
are enabled along with their interrupt. If a change
occurs on any of these three pins, an interrupt is generated. To provide a speed demand, a potentiometer is
connected to an ADC input (RB2).
To start and stop the motor, a push button switch is
provided at RC14. To provide some current feedback to
the motor, a low value resistor (25 milliohms) is connected between the DC- bus voltage and ground or
Vss. The voltage generated by this resistor is amplified
by an external op amp(MCP6002) and fed to an ADC
input (RB1).
 2004 Microchip Technology Inc.
The open-loop method is generally not practical for
actual applications. It is included here primarily to
illustrate the BLDC motor drive methodology.
Open-Loop Control
In open-loop control, the MCPWM directly controls
motor speed based on the voltage input from the Speed
Pot. After initializing the MCPWM, ADC, Ports and the
Change Notification inputs, the program waits for an
activation signal (e.g., a key press) to indicate a start
(see Figure 7). When the key is pressed, the Hall
sensors are read. Based on their value, a corresponding value is retrieved from the table and written to the
OVDCON. At this point the motor starts spinning.
FIGURE 7:
OPEN-LOOP FLOW
Start
Initialize MCPWM, ADC &
Ports
No
Key Pressed?
Yes
Read Hall Effect Sensors;
Load OVDCON with
TableLoState
No
Demand Pot Read?
Yes
Load PDCx with
Demand Value
No
Key Pressed?
Yes
Stop MCPWM using OVDCON
DS00957A-page 5
AN957
At first the duty cycle value is held at a default 50%. On
the very next loop of main program, however, the
potentiometer is read and its value (i.e., the correct
demand value) is inserted as the duty cycle. This determines the speed of the motor. The higher the duty cycle
value the faster the motor will spin. The speed is
controlled by the voltage control pot, as shown in
Figure 8.
FIGURE 8:
OPEN VOLTS CONTROL
MODE
BLDC
Motor
Voltage
Demand
dsPIC®
MCPWM
The Hall effect sensors are connected to the Change
Notification Pin. The CN interrupt is enabled. As the
rotor spins, the position of the rotor magnet changes,
and the rotor enters a different sector. Each new position is signaled by a CN Interrupt. In the CN Interrupt
routine, which is shown in Figure 9, the Hall effect
sensors are read and based on the value, a table
lookup value is got and written to the OVDCON
register. This action will insure that the correct windings
are excited in the right sector and the motor will
continue to spin.
Closed-Loop Control
In the closed-loop control version of the firmware, the
main difference is that the pot is used for setting the
demand. The control loop provides Proportional and
Integral (PI) control of the speed. To measure the
actual speed, TMR3 is used as a timer to gate a complete electrical cycle. Since we are using a 10-pole
motor, five electrical cycles result in one mechanical
cycle. If T seconds is the time for one electrical cycle
then the speed S = 60/(P/2*T) rpm, where P is the
number of poles of the motor. The control is as shown
in Figure 10. A closed-loop control flow chart is shown
in Figure 11.
FIGURE 10:
CLOSED VOLTS CONTROL
MODE
Motor
Demand
+
-
Σ
dsPIC®
MCPWM
Speed PI
Controller
Calculated Motor Speed
FIGURE 11:
CLOSED-LOOP CONTROL
FLOW
Start
FIGURE 9:
CN INTERRUPT FLOW
Start
Initialize MCPWM, ADC
and Ports
No
Read Hall Effect Sensors
Key Pressed?
Yes
Get TableLoState Value
Read Hall Effect Sensors;
Load OVDCON with
TableLoState
Load OVDCON
No
Actual Speed Read?
End
Yes
Phase Advance
For details on Phase Advance and how to implement,
please refer to AN901.
Calculate Proportional and
Integral Speed Errors *
No
Key Pressed?
Yes
Stop MCPWM using
OVDCON
* PDCx = KP(Proportional Speed Error) + KI(Integral Speed Error)
DS00957A-page 6
 2004 Microchip Technology Inc.
AN957
CONCLUSION
REFERENCES
The dsPIC30F2010 is well suited for closed-loop
control of a sensored BLDC motor. The peripherals and
DSP engine provide an excellent bandwidth for a
sensored BLDC applications with sufficient code space
available for the customer’s application program.
• AN885 – Brushless DC (BLDC) Motor
Fundamentals
• AN901 – Using the dsPIC30F for Sensorless
BLDC Control
• AN857 – Brushless DC Motor Control Made Easy
• AN889 – Brushless DC Motor Control Using
PIC18FXX31 MCUs
 2004 Microchip Technology Inc.
DS00957A-page 7
AN957
APPENDIX A:
SOURCE CODE LISTING FOR OPEN-LOOP CONTROL
This appendix contains the source code listing for open-loop control.
Software License Agreement
The software supplied herewith by Microchip Technology Incorporated (the “Company”) is intended and supplied to you, the
Company’s customer, for use solely and exclusively with products manufactured by the Company.
The software is owned by the Company and/or its supplier, and is protected under applicable copyright laws. All rights are reserved.
Any use in violation of the foregoing restrictions may subject the user to criminal sanctions under applicable laws, as well as to civil
liability for the breach of the terms and conditions of this license.
THIS SOFTWARE IS PROVIDED IN AN “AS IS” CONDITION. NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR
SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
//--------------------------------------------------------------------------------//
Software License Agreement
//
// The software supplied herewith by Microchip Technology Incorporated
// (the “Company”) is intended and supplied to you, the Company’s customer,
// for use solely and exclusively with products manufacture by the Company.
// The software is owned by the Company and/or its supplier, and is protected under
// applicable copyright laws. All rights are reserved. Any use in violation of the
// foregoing restrictions may subject the user to criminal sanctions under applicable
// laws, as well as to civil liability for the breach of the terms and conditions of
// this license.
//
// THIS SOFTWARE IS PROVIDED IN AN “AS IS” CONDITION. NO WARRANTIES, WHETHER EXPRESS,
// IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
// THE COMPANY SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR
// CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
//--------------------------------------------------------------------------------// File: ClosedLoopSenBLDC.c
//
// Written By:Stan D'Souza, Microchip Technology
//
// The following files should be included in the MPLAB project:
//
//
ClosedLoopSenBLDC.c-- Main source code file
//
p30f2010.gld-- Linker script file
//
//
//--------------------------------------------------------------------//
// Revision History
//
// 10/01/04 -- first version
//---------------------------------------------------------------------/*************************************************************
Low side driver table is as below. In this StateLoTable,
the Low side driver is PWM while the high side driver is
either on or off. This table is used in this exercise
*************************************************************/
unsigned int StateLoTable[] = {0x0000, 0x0210, 0x2004, 0x0204,
0x0801, 0x0810, 0x2001, 0x0000};
/****************************************************************
Interrupt vector for Change Notification CN5, 6 and 7 is as below.
When a Hall sensor changes states, an interrupt will be caused
which will vector to the routine below.
The user has to then read the PORTB, mask bits 3, 4 and 5,
shift and adjust the value to read as 1, 2 ... 6. This
value is then used as an offset in the lookup table StateLoTable
to determine the value loaded in the OCDCON register
*****************************************************************/
DS00957A-page 8
 2004 Microchip Technology Inc.
AN957
void _ISR _CNInterrupt(void)
{
IFS0bits.CNIF = 0;
// clear flag
HallValue = PORTB & 0x0038;
// mask RB3,4 & 5
HallValue = HallValue >> 3;
// shift right 3 times
OVDCON = StateLoTable[HallValue];
}
/*********************************************************************
The ADC interrupt loads the PDCx registers with the demand pot value.
This is only done when the motor is running.
*********************************************************************/
void _ISR _ADCInterrupt(void)
{
IFS0bits.ADIF = 0;
if (Flags.RunMotor)
{
PDC1 = ADCBUF0;
PDC2 = PDC1;
PDC3 = PDC1;
}
}
// get value ...
// and load all three PWMs ...
// duty cycles
int main(void)
{
LATE = 0x0000;
TRISE = 0xFFC0;
// PWMs are outputs
CNEN1 = 0x00E0;
// CN5,6 and 7 enabled
CNPU1 = 0x00E0;
// enable internal pullups
IFS0bits.CNIF = 0;
// clear CNIF
IEC0bits.CNIE = 1;
// enable CN interrupt
InitMCPWM();
InitADC10();
while(1)
{
while (!S2);
// wait for start key hit
while (S2)
// wait till key is released
DelayNmSec(10);
// read hall position sensors on PORTB
HallValue = PORTB & 0x0038;
// mask RB3,4 & 5
HallValue = HallValue >> 3;
// shift right to get value 1, 2 ... 6
OVDCON = StateLoTable[HallValue]; // Load the overide control register
PWMCON1 = 0x0777;
// enable PWM outputs
Flags.RunMotor = 1;
// set flag
while (Flags.RunMotor)
// while motor is running
if (S2)
// if S2 is pressed
{
PWMCON1 = 0x0700;
// disable PWM outputs
OVDCON = 0x0000;
// overide PWM low.
Flags.RunMotor = 0;
// reset run flag
while (S2)
// wait for key release
DelayNmSec(10);
}
} // end of while (1)
}
 2004 Microchip Technology Inc.
DS00957A-page 9
AN957
/*******************************************************************
Below is the code required to setup the ADC registers for :
1. 1 channel conversion (in this case RB2/AN2)
2. PWM trigger starts conversion
3. Pot is connected to CH0 and RB2
4. Manual Stop Sampling and start converting
5. Manual check of Conversion complete
*********************************************************************/
void InitADC10(void)
{
ADPCFG = 0xFFF8;
ADCON1 = 0x0064;
ADCON2 = 0x0200;
ADCHS = 0x0002;
ADCON3 = 0x0080;
IFS0bits.ADIF = 0;
IEC0bits.ADIE = 1;
ADCON1bits.ADON = 1;
}
//
//
//
//
//
//
all PORTB = Digital;RB0 to RB2 = analog
PWM starts conversion
simulataneous sample 4 channels
Connect RB2/AN2 as CH0 = pot ..
ch1 = Vbus, Ch2 = Motor, Ch3 = pot
Tad = internal RC (4uS)
// turn ADC ON
/********************************************************************
InitMCPWM, intializes the PWM as follows:
1. FPWM = 16000 hz
2. Independant PWMs
3. Control outputs using OVDCON
4. Set Duty Cycle with the ADC value read from pot
5. Set ADC to be triggered by PWM special trigger
*********************************************************************/
void InitMCPWM(void)
{
PTPER = FCY/FPWM - 1;
PWMCON1 = 0x0700;
OVDCON = 0x0000;
PDC1 = 100;
PDC2 = 100;
PDC3 = 100;
SEVTCMP = PTPER;
PWMCON2 = 0x0F00;
PTCON = 0x8000;
// disable PWMs
// allow control using OVD
// init PWM 1, 2 and 3 to 100
// 16 postscale values
// start PWM
}
//--------------------------------------------------------------------// This is a generic 1ms delay routine to give a 1mS to 65.5 Seconds delay
// For N = 1 the delay is 1 mS, for N = 65535 the delay is 65,535 mS.
// Note that FCY is used in the computation. Please make the necessary
// Changes(PLLx4 or PLLx8 etc) to compute the right FCY as in the define
// statement above.
void DelayNmSec(unsigned int N)
{
unsigned int j;
while(N--)
for(j=0;j < MILLISEC;j++);
}
DS00957A-page 10
 2004 Microchip Technology Inc.
AN957
APPENDIX B:
SOURCE CODE LISTING FOR CLOSED LOOP CONTROL
This appendix contains the source code listing for closed loop control.
//--------------------------------------------------------------------------------//
Software License Agreement
//
// The software supplied herewith by Microchip Technology Incorporated
// (the “Company”) is intended and supplied to you, the Company’s customer,
// for use solely and exclusively with products manufacture by the Company.
// The software is owned by the Company and/or its supplier, and is protected under
// applicable copyright laws. All rights are reserved. Any use in violation of the
// foregoing restrictions may subject the user to criminal sanctions under applicable
// laws, as well as to civil liability for the breach of the terms and conditions of
// this icense.
//
// THIS SOFTWARE IS PROVIDED IN AN “AS IS” CONDITION. NO WARRANTIES, WHETHER EXPRESS,
// IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
// THE COMPANY SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR
// CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
//--------------------------------------------------------------------------------// File: ClosedLoopSenBLDC.c
//
// Written By:Stan D'Souza, Microchip Technology
//
// The following files should be included in the MPLAB project:
//
//
ClosedLoopSenBLDC.c-- Main source code file
//
p30f2010.gld-- Linker script file
//
//--------------------------------------------------------------------// Revision History
//
// 10/01/04 -- first version
//--------------------------------------------------------------------//***************************************************************************
ClosedLoopSenBLDC.c is a sensored Closed Loop Control for a BLDC motor.
The task consists of the following:
Sense changes in the Hall Sensors connected to CN5,6 & 7 (PortB)
During the CNInterrupt, read the sensors input by reading PortB
Mask and determine the state of the position 1, 2, ... 6.
Use the StateLoTable and the lookup table provided to determine the
Overload Control Register value. Set the OVDCON to this value.
The PWM is initialized to generate independant continuous PWMs.
The value of the Pot REF is used to determine the demand or desired
speed of the Motor. The desired speed value is then used with the
actual speed value to determine the Proportional Speed Error and the
Integral Speed Error. With these two values the new DutyCycle is determined
as: NewDutyCycle = Kp*(Portportional Speed Error) + Ki*(Integral Speed Error)
All 3 PWM Duty cycles are then loaded with the NewDutyCycloe 10-bit value.
The FPWM = 16000hz
The ADC is setup for a PWM trigger to start the conversion
********************************************************************************/
 2004 Microchip Technology Inc.
DS00957A-page 11
AN957
#define __dsPIC30F2010__
#include "c:\pic30_tools\support\h\p30F2010.h"
#define
#define
#define
#define
#define
#define
FCY 10000000// xtal = 5.0Mhz; PLLx8
MILLISEC FCY/10000// 1 mSec delay constant
FPWM 16000
Ksp1200
Ksi10
RPMConstant60*(FCY/256)
#define S2!PORTCbits.RC14
void
void
void
void
void
void
void
InitTMR3(void);
InitADC10(void);
AverageADC(void);
DelayNmSec(unsigned int N);
InitMCPWM(void);
CalculateDC(void);
GetSpeed(void);
struct {
}
unsigned RunMotor : 1;
unsigned Minus : 1;
unsigned unused : 14;
Flags;
unsigned int HallValue;
int Speed;
unsigned int Timer3;
unsigned char Count;
unsigned char SpeedCount;
int DesiredSpeed;
int ActualSpeed;
int SpeedError;
int DutyCycle;
int SpeedIntegral;
//*************************************************************
Low side driver table is as below. In this StateLoTable,
the Low side driver is PWM while the high side driver is
either on or off. This table is used in this exercise
*************************************************************/
unsigned int StateLoTable[] = {0x0000, 0x1002, 0x0420, 0x0402,
0x0108, 0x1008, 0x0120, 0x0000};
/****************************************************************
Interrupt vector for Change Notification CN5, 6 and 7 is as below.
When a Hall sensor changes states, an interrupt will be caused which
will vector to the routine below.
The user has to then read the PORTB, mask bits 3, 4 and 5,
shift and adjust the value to read as 1, 2 ... 6. This
value is then used as an offset in the lookup table StateLoTable
to determine the value loaded in the OCDCON register
*****************************************************************/
DS00957A-page 12
 2004 Microchip Technology Inc.
AN957
void _ISR _CNInterrupt(void)
{
IFS0bits.CNIF = 0;
//
HallValue = PORTB & 0x0038;
//
HallValue = HallValue >> 3;
//
OVDCON = StateLoTable[HallValue];//
}
clear flag
mask RB3,4 & 5
shift right 3 times
Load the overide control register
/*********************************************************************
The ADC interrupt loads the DesiredSpeed variable with the demand pot
value. This is then used to determing the Speed error. When the motor
is not running, the PDC values use the direct Demand value from the pot.
*********************************************************************/
void _ISR _ADCInterrupt(void)
{
IFS0bits.ADIF = 0;
DesiredSpeed = ADCBUF0;
if (!Flags.RunMotor)
{
PDC1 = ADCBUF0;
// get value ...
PDC2 = PDC1;
// and load all three PWMs ...
PDC3 = PDC1;
// duty cycles
}
}
/************************************************************************
The main routine controls the initialization, and the keypress to start
and stop the motor.
************************************************************************/
int main(void)
{
LATE = 0x0000;
TRISE = 0xFFC0;
// PWMs are outputs
CNEN1 = 0x00E0;
// CN5,6 and 7 enabled
CNPU1 = 0x00E0;
// enable internal pullups
IFS0bits.CNIF = 0;
// clear CNIF
IEC0bits.CNIE = 1;
// enable CN interrupt
SpeedError = 0;
SpeedIntegral = 0;
InitTMR3();
InitMCPWM();
InitADC10();
while(1)
{
while (!S2);
// wait for start key hit
while (S2)
// wait till key is released
DelayNmSec(10);
// read hall position sensors on PORTB
HallValue = PORTB & 0x0038;
// mask RB3,4 & 5
HallValue = HallValue >> 3;
// shift right to get value 1, 2 ... 6
OVDCON = StateLoTable[HallValue];// Load the overide control register
PWMCON1 = 0x0777;
// enable PWM outputs
Flags.RunMotor = 1;
// set flag
T3CON = 0x8030;
// start TMR3
while (Flags.RunMotor)
// while motor is running
if (!S2)
// if S2 is not pressed
 2004 Microchip Technology Inc.
DS00957A-page 13
AN957
{
if (HallValue == 1)
{
HallValue = 0xFF;
if (++Count == 5)
//IF in sector 1
// force a new value as a sector
// do this for 5 electrical revolutions or 1
// mechanical revolution for a 10 pole motor
{
Timer3 = TMR3;// read latest tmr3 value
TMR3 = 0;
Count = 0;
GetSpeed();// determine spped
}
}
}
}
else
// else S2 is pressed to stop motor
{
PWMCON1 = 0x0700;// disable PWM outputs
OVDCON = 0x0000; // overide PWM low.
Flags.RunMotor = 0;// reset run flag
while (S2)// wait for key release
DelayNmSec(10);
}
// end of while (1)
}
/*******************************************************************
Below is the code required to setup the ADC registers for :
1. 1 channel conversion (in this case RB2/AN2)
2. PWM trigger starts conversion
3. Pot is connected to CH0 and RB2
4. Manual Stop Sampling and start converting
5. Manual check of Conversion complete
*********************************************************************/
void InitADC10(void)
{
ADPCFG = 0xFFF8;
ADCON1 = 0x0064;
ADCON2 = 0x0000;
ADCHS = 0x0002;
ADCON3 = 0x0080;
IFS0bits.ADIF = 0;
IEC0bits.ADIE = 1;
ADCON1bits.ADON = 1;
}
DS00957A-page 14
//
//
//
//
//
//
//
all PORTB = Digital;RB0 to RB2 = analog
PWM starts conversion
sample CH0 channel
Connect RB2/AN2 as CH0 = pot.
Tad = internal RC (4uS)
clear flag
enable interrupt
// turn ADC ON
 2004 Microchip Technology Inc.
AN957
/********************************************************************
InitMCPWM, intializes the PWM as follows:
1. FPWM = 16000 hz
2. Independant PWMs
3. Control outputs using OVDCON
4. Set Duty Cycle using PI algorithm and Speed Error
5. Set ADC to be triggered by PWM special trigger
*********************************************************************/
void InitMCPWM(void)
{
PTPER = FCY/FPWM - 1;
PWMCON1 = 0x0700;
OVDCON = 0x0000;
PDC1 = 100;
PDC2 = 100;
PDC3 = 100;
SEVTCMP = PTPER;
PWMCON2 = 0x0F00;
PTCON = 0x8000;
// disable PWMs
// allow control using OVD
// init PWM 1, 2 and 3 to 100
// special trigger is 16 period values
// 16 postscale values
// start PWM
}
/************************************************************************
Tmr3 is used to determine the speed so it is set to count using Tcy/256
*************************************************************************/
void InitTMR3(void)
{
T3CON = 0x0030;
TMR3 = 0;
PR3 = 0x8000;
}
// internal Tcy/256 clock
/************************************************************************
GetSpeed, determins the exact speed of the motor by using the value in
TMR3 for every mechanical cycle.
*************************************************************************/
void GetSpeed(void)
{
if (Timer3 > 23000)
// if TMR3 is large ignore reading
return;
if (Timer3 > 0)
Speed = RPMConstant/(long)Timer3;// get speed in RPM
ActualSpeed += Speed;
ActualSpeed = ActualSpeed >> 1;
if (++SpeedCount == 1)
{SpeedCount = 0;CalculateDC();}
}
 2004 Microchip Technology Inc.
DS00957A-page 15
AN957
/*****************************************************************************
CalculateDC, uses the PI algorithm to calculate the new DutyCycle value which
will get loaded into the PDCx registers.
****************************************************************************/
void CalculateDC(void)
{
DesiredSpeed = DesiredSpeed*3;
Flags.Minus = 0;
if (ActualSpeed > DesiredSpeed)
SpeedError = ActualSpeed - DesiredSpeed;
else
{
SpeedError = DesiredSpeed - ActualSpeed;
Flags.Minus = 1;
}
SpeedIntegral += SpeedError;
if (SpeedIntegral > 9000)
SpeedIntegral = 0;
DutyCycle = (((long)Ksp*(long)SpeedError + (long)Ksi*(long)SpeedIntegral) >> 12);
DesiredSpeed = DesiredSpeed/3;
if (Flags.Minus)
DutyCycle = DesiredSpeed + DutyCycle;
else DutyCycle = DesiredSpeed - DutyCycle;
if (DutyCycle < 100)
DutyCycle = 100;
if (DutyCycle > 1250)
{DutyCycle = 1250;SpeedIntegral = 0;}
PDC1 = DutyCycle;
PDC2 = PDC1;
PDC3 = PDC1;
}
//--------------------------------------------------------------------// This is a generic 1ms delay routine to give a 1mS to 65.5 Seconds delay
// For N = 1 the delay is 1 mS, for N = 65535 the delay is 65,535 mS.
// Note that FCY is used in the computation. Please make the necessary
// Changes(PLLx4 or PLLx8 etc) to compute the right FCY as in the define
// statement above.
void DelayNmSec(unsigned int N)
{
unsigned int j;
while(N--)
for(j=0;j < MILLISEC;j++);
}
DS00957A-page 16
 2004 Microchip Technology Inc.
SCHEMATICS
FIGURE C-1:
MOTOR CONTROL SCHEMATIC 1
This appendix contains schematic diagrams for using the dsPIC30F2010 to control a sensored BLDC motor.
APPENDIX C:
AN957
 2004 Microchip Technology Inc.
DS00957A-page 17
FIGURE C-2:
DS00957A-page 18
VB 8
HO 7
VS 6
VB 8
HO 7
VS 6
VCC 1
LO 5
COM 4
VCC 1
LO 5
COM 4
VB 8
HO 7
VS 6
VCC 1
LO 5
COM 4
2 HIN
3 LIN
2 HIN
3 LIN
2 HIN
3 LIN
MOTOR CONTROL SCHEMATIC 2
AN957
 2004 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
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Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
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MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
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RELATED TO THE INFORMATION, INCLUDING BUT NOT
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Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
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AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL,
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are registered trademarks of Microchip Technology
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Programming, ICSP, ICEPIC, Migratable Memory, MPASM,
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PICLAB, PICtail, PowerCal, PowerInfo, PowerMate,
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SmartTel and Total Endurance are trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2004, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
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Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
 2004 Microchip Technology Inc.
DS00957A-page 19
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DS00957A-page 20
 2004 Microchip Technology Inc.
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