ETC DRM022

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3-Phase BLDC Drive
Control with
Hall Sensors
Reference Design
Designer Reference
Manual
M68HC08
Microcontrollers
DRM022/D
Rev. 1, 03/2003
MOTOROLA.COM/SEMICONDUCTORS
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3-Phase BLDC Drive Control
with Hall Sensors Reference
Design
Designer Reference Manual — Rev 1
by: Jiri Ryba, Petr Stekl
Motorola Czech Systems Laboratories
Roznov pod Radhostem, The Czech Republic
DRM022 — Rev 1
Designer Reference Manual
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Revision history
To provide the most up-to-date information, the revision of our
documents on the World Wide Web will be the most current. Your printed
copy may be an earlier revision. To verify you have the latest information
available, refer to:
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The following revision history table summarizes changes contained in
this document. For your convenience, the page number designators
have been linked to the appropriate location.
Revision history
Date
Revision
Level
January,
2003
1
Description
Initial revision
Page
Number(s)
N/A
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
List of Sections
Section 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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Section 2. System Description. . . . . . . . . . . . . . . . . . . . . 15
Section 3. Hardware Design. . . . . . . . . . . . . . . . . . . . . . . 23
Section 4. Software Design . . . . . . . . . . . . . . . . . . . . . . . 37
Section 5. Application Setup . . . . . . . . . . . . . . . . . . . . . . 47
Appendix A. References. . . . . . . . . . . . . . . . . . . . . . . . . . 61
Appendix B. Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
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List of Sections
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Table of Contents
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Section 1. Introduction
1.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.2
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.3
Brief Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4
68HC908MR32 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Section 2. System Description
2.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
2.2
Application Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3
Brushless DC Motor Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4
Digital Control of BLDC Motor . . . . . . . . . . . . . . . . . . . . . . . . . 19
Section 3. Hardware Design
3.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
3.2
Hardware Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3
MC68HC908MR32 Control Board . . . . . . . . . . . . . . . . . . . . . . 25
3.4
3-Ph BLDC Low Voltage Power Stage . . . . . . . . . . . . . . . . . . . 27
3.5
EVM Motor Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.6
Optoisolation Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.7
3-Phase AC BLDC High Voltage Power Stage. . . . . . . . . . . . . 33
3.8
Hardware Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Section 4. Software Design
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Table of Contents
4.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
4.2
Software Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.3
Software Data Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4
Software Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.5
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
4.6
Main Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.7
Application Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.8
PC Master Software (Remote) Operating Mode. . . . . . . . . . . . 45
Section 5. Application Setup
5.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
5.2
Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.3
Hardware Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.4
Software Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.5
Executing the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Appendix A. References
Appendix B. Glossary
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
List of Tables
Table
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2-1
2-2
3-1
3-2
3-3
3-4
3-5
3-6
5-1
5-2
Title
Page
Vector to sensor code assignment . . . . . . . . . . . . . . . . . . . . . . 21
Commutation table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Electrical Characteristics of the Control Board . . . . . . . . . . . . . 27
Electrical Characteristics of the
3-Ph BLDC Low Voltage Power Stage . . . . . . . . . . . . . . . . . . . 29
Electrical Characteristics of the EVM Motor Board. . . . . . . . . . 30
Characteristics of the BLDC motor . . . . . . . . . . . . . . . . . . . . . . 31
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Electrical Characteristics of Power Stage. . . . . . . . . . . . . . . . . 35
MCHC908MR32 Board Jumper Settings . . . . . . . . . . . . . . . . . 51
Motor Application States. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
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List of Tables
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
List of Figures
Figure
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2-1
2-2
2-3
2-4
3-1
3-2
3-3
3-4
3-5
4-1
4-2
5-1
5-2
5-3
5-4
5-5
5-6
5-7
Title
Page
System Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
BLDC Motor - Cross Section . . . . . . . . . . . . . . . . . . . . . . . . . . 17
BLDC Motor - Back EMF and Magnetic Flux,
Hall Sensor Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Three phase voltage system applied to a BLDC motor . . . . . . 20
H/W System configuration for low voltage motor . . . . . . . . . . . 24
H/W System configuration for high voltage motor . . . . . . . . . . 25
MC68HC908MR32 Control Board . . . . . . . . . . . . . . . . . . . . . . 26
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3-Phase AC High Voltage Power Stage . . . . . . . . . . . . . . . . . . 34
Main Data Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Application State Machine Diagram . . . . . . . . . . . . . . . . . . . . . 44
H/W System Configuration for low voltage motor . . . . . . . . . . . 49
H/W System Configuration for high voltage motor . . . . . . . . . . 50
MC68HC908MR32 Jumper Reference. . . . . . . . . . . . . . . . . . . 51
Target Build Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
MC68HC908MR32 Board - Control Elements . . . . . . . . . . . . . 55
USER LEDs, PWM LEDs, and RESET . . . . . . . . . . . . . . . . . . 55
PC Master Control Window . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
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List of Figures
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Section 1. Introduction
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1.1 Contents
1.2
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.3
Brief Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4
68HC908MR32 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2 Overview
This reference design describes a 3-phase 4-quadrant sensor BLDC
motor drive, which can run in both a speed open loop and a speed closed
loop. The application is designed for MC68HC908MRxx family
dedicated to motor control applications. This reference design includes
a description of the Motorola 68HC908MR32 features, basic motor
theory, system design concept, hardware implementation, and software
design including the PC Master visualization tool.
1.3 Brief Description
The position of the motor is sensed by the Hall sensors. The BLDC
algorithm sets the proper voltage vector on the BLDC motor with respect
to the sensed position. The amplitude of voltage is set according to
required speed and actual load. When the amplitude reaches the
maximum, the BLDC motor is de-excited by advancing the voltage
vector to further increase the speed.
The concept of the application allows both closed and open-loop speed
control. It serves as an example of a sensor BLDC motor control system
using Motorola’s M68HC08 Family. It also illustrates the usage of
dedicated motor control on chip peripherals.
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Introduction
This BLDC motor control application with Hall sensors can operate in
two modes:
•
Manual operating mode
•
PC master software (remote) operating mode
1.4 68HC908MR32 Features
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The Motorola MR32 family members are well suited for digital motor
control. These MCUs offer many dedicated peripherals such as a Pulse
Width Modulation (PWM) module, Analog-to-Digital Converter (ADC),
Timers, Serial communication interface (SCI), on-board Flash and RAM.
A typical member of the family, the 68HC908MR32, provides the
following peripheral blocks:
•
12-bit, 6-channel center-aligned or edge-aligned Pulse Width
Modulator module with optional Independent and Complementary
mode
•
32Kbytes of on-chip electrically erasable in-circuit programmable
Read Only Memory (FLASH EPROM)
•
768 bytes of on-chip Random Access Memory (RAM)
•
Ten channels 10-bit Analog-to-Digital Converters (ADC) with
multiplexed inputs
•
Two 16-bits 2-channel timer modules
•
Serial communications interface module (SCI)
•
Clock generator module (CGM)
•
Computer Operating Properly (COP) watchdog timer
•
Low-voltage inhibit (LVI) module with software selectable trip
points
•
Software-programmable, Phase Lock Loop-based frequency
synthesizer for the core clock
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Introduction
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Section 2. System Description
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2.1 Contents
2.2
Application Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3
Brushless DC Motor Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4
Digital Control of BLDC Motor . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2 Application Features
The control strategy is designed to optimally utilize features of controller
68HC908MR32. The application provides following properties:
•
voltage control of BLDC motor
•
position sensing using 3 Hall sensors
•
closed or open speed loop operation
•
both directions of rotation
•
Hall sensors identification algorithm
•
field weakening to achieve higher speed
•
manual (speed pot, start-stop switch) / PC master control (RS 232)
•
over and under voltage protection
•
over current protection
•
PC master software
•
memory requirements
– RAM 187 Bytes
– Flash 6198 Bytes
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System Description
The system is designed to drive a 3-phase BLDC motor. The MCU runs
the main control algorithm. According to the user interface input and
feedback signals, it generates 3-phase PWM output signals for the
motor inverter. A standard system concept is chosen for the drive see
Figure 2-1
68HC908MRxx
YELLOW
RED
CONTROL
STRATEGY
DC
Line
PWM
COMMUTATION
HANDLER
EVM
MOTOR
BOARD
AC
TIMER
GREEN
PORT C
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PC MASTER
RS232
u
α
PI
CONTROLLER
Angle
PORT F
SPEED POT
ADC
u
BLDC
POSITION
SENSORS
ω
CLOSE LOOP
SENSOR DET.
SPEED
CALCULATION
IRQ
PORT E
FW/REV
PORT A
START/STOP
EOR
Figure 2-1. System Concept
The control process is as follows:
The state of the switches is scanned periodically. The Hall Sensor
signals are scanned in the interrupt, which is called on each coming
edge of any Hall Sensor signal. Also new voltage vector is applied to the
BLDC motor. This process is called commutation. If the motor is
de-excited advancing of the voltage vector is required. In this case the
voltage vector for following sensor state is applied with appropriate delay
made by preset counter.
The speed PI controller is calculated independently in the timer interrupt
every 10ms. Output of the controller is required motor voltage. If running
in open loop control the controller is not used the Speed pot position is
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System Description
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System Description
Brushless DC Motor Theory
used to set required motor voltage. The measured speed of the motor is
calculated from sensor edge period. Since the three phase motor is
used, the three last periods are add to eliminate angle error between the
sensors. Then using of edges from same sensor is secured for speed
calculation.
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Undervoltage protection of the DC Bus is sensed during the control
process and is performed by software.
The application also contains PC master software, which supports
communication between the target microcontroller and PC via an RS232
serial interface. This tool allows access to any memory location of the
target processor in real time. The programmer can debug an application,
as well as remotely control the application, using a user-friendly
graphical environment running on a PC.
2.3 Brushless DC Motor Theory
A brushless DC (BLDC) motor is a rotating electric machine where the
stator is a classic three-phase stator like that of an induction motor and
the rotor has surface-mounted permanent magnets (see Figure 2-2)
Stator
Stator winding
(in slots)
Shaft
Rotor
Air gap
Permanent magnets
Figure 2-2. BLDC Motor - Cross Section
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In this respect, the BLDC motor is equivalent to a reversed DC
commutator motor, in which the magnet rotates while the conductors
remain stationary. In the DC commutator motor, the current polarity is
altered by the commutator and brushes. On the contrary, in the
brushless DC motor, the polarity reversal is performed by power
transistors switching in synchronization with the rotor position.
Therefore, BLDC motors often incorporate either internal or external
position sensors to sense the actual rotor position or the position can be
detected without sensors.
The presented application uses three Hall Sensors to sense actual
position. The Hall Sensors’ signals together give the six output values.
These outputs are read by MCU and the corresponding output voltage is
generated by PWM outputs (see Figure 2-3).
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System Description
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System Description
Digital Control of BLDC Motor
Psi_A
Psi_B
Psi_C
Ui_A
Ui_B
Ui_C
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Atop
Btop
Cbot
Ctop
Abot
Bbot
Ui_AB
Ui_AB
150,0
Ui_BC
Ui_BC
Ui_CA
Ui_CA
100,0
50,0
0,0
0,0000
0,0200
0,0400
0,0600
0,0800
0,1000
0,1200
0,1400
0,1600
0,1800
0,2000
-50,0
-100,0
-150,0
Pos_A
Pos_B
Pos_C
Figure 2-3. BLDC Motor - Back EMF and Magnetic Flux,
Hall Sensor Outputs
2.4 Digital Control of BLDC Motor
The brushless DC motor (BLDC motor) is also known as an
electronically commuted motor. There are no brushes on the rotor and
the commutation is performed electronically at certain rotor positions.
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System Description
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The three phase voltage system (see Figure 2-4) with a rectangular
shape is used to create a rotational torque.
electrical
angle
Figure 2-4. Three phase voltage system applied to a BLDC motor
This easily created shape of applied voltage ensures the simplicity of
control of a drive. The rotor position must be known in order to align
energized phases with the rotor’s permanent magnetic field. The
alignment is very important because it results in proper commutation in
the PWM inverter where the voltage level is reduced by chopping. In this
condition the motor behaves as a DC motor and runs at the best working
point. The simplicity of control and good performance makes this motor
a natural choice for low-cost and high-efficiency applications. There are
many methods how to provide alignment between rotor position and
commutation events. The presented application use Hall sensors to
sense the commutation events.
2.4.1 Commutation Algorithm
The commutation algorithm provides the generation of a rotational field
according to rotor position.
This algorithm uses the Hall sensors to obtain the rotor position. The Hall
sensor consists of three sensors (Sensor A, Sensor B, Sensor C). The
HC908MR32 control board contains EOR logic, which reflect change of
any sensor to the one output. This output is connected to the channel 2
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System Description
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System Description
Digital Control of BLDC Motor
of timer A. The timer channel is set to catch edges of the input signal and
call interrupt routine, which provides commutation algorithm. In the
interrupt the current state of all sensors is read. These sensors comprise
six states (001, 010, 011, 100, 101, 110). Each state corresponds to
actual rotor position, which determines required direction of voltage
vector. The value of sensors state is used as a pointer to the vector table
(see Table 2-1), which is used to call appropriate commutation function.
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Table 2-1. Vector to sensor code assignment
Hall Sensor A
Hall Sensor B
Hall Sensor C
Rotor Position
0
0
0
None
0
0
1
120
0
1
0
0
0
1
1
60
1
0
0
240
1
0
1
180
1
1
0
300
1
1
1
None
The angle of rotor position represents magnetic flux vector in the middle
between edge for clockwise and counter clockwise rotation, while the
phase A is placed to real axis. It means that zero degree is obtained
when the flux of phase A is in the positive maximum. From the rotor
position the voltage vector is calculated according to required direction
and speed. Then appropriate commutation function is called. The PWM
switching schema is in the commutation table (see Table 2-2). For
details on commutation algorith see section 4.4.8 Commutation
Algorithm.
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System Description
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Table 2-2. Commutation table
Voltage Vector
(required)
Phase A
Phase B
Phase C
30
+VDCB
NC
-VDCB
90
NC
+VDCB
-VDCB
150
-VDCB
+VDCB
NC
210
-VDCB
NC
+VDCB
270
NC
-VDCB
+VDCB
330
+VDCB
-VDCB
NC
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Section 3. Hardware Design
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3.1 Contents
3.2
Hardware Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3
MC68HC908MR32 Control Board . . . . . . . . . . . . . . . . . . . . . . 25
3.4
3-Ph BLDC Low Voltage Power Stage . . . . . . . . . . . . . . . . . . . 27
3.5
EVM Motor Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.6
Optoisolation Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.7
3-Phase AC BLDC High Voltage Power Stage. . . . . . . . . . . . . 33
3.8
Hardware Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2 Hardware Configuration
The motor control system is designed to drive the 3-phase BLDC motor
in a speed closed loop using a 68HC908MR32 microcontroller. The
system can be configured to run with different motors. System
configuration for low voltage motors consists of:
•
Motorola MC68HC908MR32 control board
•
3-phase BLDC low voltage power stage or EVM motor board
•
3-phase BLDC motor with Hall sensors
The system configuration is shown in the Figure 3-1
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Hardware Design
40w flat
ribbon
cable
U1
U3
J5
U2
12V DC
Freescale Semiconductor, Inc...
J2
Hall sensor cable
M1
U1 – 68HC908MR32 MC Board
U2 –3-Ph Low Voltage BLDC Power Stage or Evaluation
Motor Board
U3 – 68HC908MR32 Daughter Board
M1 – 3 phase BLDC Motor
Figure 3-1. H/W System configuration for low voltage motor
The system configuration for high voltage motors consists of:
•
Motorola MC68HC908MR32 control board
•
Optoisolation board
•
3-phase AC/BLDC high voltage power stage
•
3-phase BLDC motor with Hall sensors
The system configuration is shown in the Figure 3-2.
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Hardware Design
MC68HC908MR32 Control Board
40w flat
ribbon
cable
U1
J5
U4
12 V DC
U2
40w flat
ribbon
cable
U3
230/115 V
AC
Freescale Semiconductor, Inc...
J2
Hall sensor cable
M1
U1 – 68HC908MR32 MC Board
U2 –Optoisolation Board
U3 –3-Ph High Voltage AC/BLDC Power Stage
U4 – 68HC908MR32 Daughter Board
M1 – 3 phase BLDC Motor
Figure 3-2. H/W System configuration for high voltage motor
3.3 MC68HC908MR32 Control Board
Motorola’s embedded motion control series MR32 motor control board is
designed to provide control signals for 3-phase ac induction, 3-phase
brushless dc (BLDC), and 3-phase switched reluctance (SR) motors. In
combination with one of the embedded motion control series power
stages, and an optoisolation board, it provides a software development
platform that allows algorithms to be written and tested without the need
to design and build hardware. With software supplied on the CD-ROM,
the control board supports a wide variety of algorithms for ac induction,
SR, and BLDC motors. User control inputs are accepted from
START/STOP, FWD/REV switches, and a SPEED potentiometer
located on the control board. Alternately, motor commands can be
entered via a PC and transmitted over a serial cable to DB-9 connector.
Output connections and power stage feedback signals are grouped
together on 40-pin ribbon cable connector. Motor feedback signals can
be connected to Hall sensor/encoder connector. Power is supplied
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through the 40-pin ribbon cable from the optoisolation board or
low-voltage power stage.
The control board is designed to run in two configurations. It can be
connected to an M68EM08MR32 emulator via an M68CBL08A
impedance matched ribbon cable, or it can operate using the daughter
board. The M68EM08MR32 emulator board may be used in either an
MMDS05/08 or MMEVS05/08 emulation system.
TERMINAL
I/F
OPTOISOLATED
RS-232 I/F
FORWARD/REVERSE
SWITCH
TACHOMETER
INPUT
START/STOP
SWITCH
EMULATOR/
PROCESSOR
CONNECTOR
dc POWER
12 Vdc
SPEED
POT
REGULATED
POWER SUPPLY
HALL EFFECT
INPUTS (3)
RESET
SWITCH
CONFIG.
JUMPERS
Freescale Semiconductor, Inc...
Figure 3-3 shows a block diagram of the board’s circuitry.
(2) OPTION
SWITCHES
PWM LEDs (6)
OPTO/POWER DRIVER I/O CONNECTOR
OVERCURRENT/
OVERVOLTAGE
INPUTS
BACK EMF
INPUTS
CURRENT/TEMP
SENSE INPUTS
PWM (6)
OUTPUTS
40-PIN RIBBON
CONNECTOR
MISC. POWER AND
CONTROL I/O
Figure 3-3. MC68HC908MR32 Control Board
The electrical characteristics in Table 3-1 apply to operation at 25°C.
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3-Ph BLDC Low Voltage Power Stage
Table 3-1. Electrical Characteristics of the Control Board
Symb
ol
Min
Type
Max
Units
dc power supply voltage(1)
Vdc
10.8
12
16.5
V
Quiescent current
ICC
—
80
—
mA
Min logic 1 input voltage
(MR32)
VIH
2.0
—
—
V
Max logic 0 input voltage
(MR32)
VIL
—
—
0.8
V
Propagation delay
(Hall sensor/encoder input)
tdly
—
—
500
ns
Analog input range
VIn
0
—
5.0
V
—
—
9600
Baud
—
—
20
mA
Freescale Semiconductor, Inc...
Characteristic
RS-232 connection speed
PWM sink current
IPK
1. When operated and powered separately from other Embedded Motion Control tool set
products
3.4 3-Ph BLDC Low Voltage Power Stage
Motorola’s embedded motion control series low-voltage (LV) brushless
DC (BLDC) power stage is designed to run 3-ph. BLDC and PM
Synchronous motors. It operates from a nominal 12-volt motor supply,
and delivers up to 30 amps of rms motor current from a dc bus that can
deliver peak currents up to 46 amps. In combination with one of
Motorola’s embedded motion control series control boards, it provides a
software development platform that allows algorithms to be written and
tested, without the need to design and build a power stage. It supports a
wide variety of algorithms for controlling BLDC motors and PM
Synchronous motors.
Input connections are made via 40-pin ribbon cable connector J13.
Power connections to the motor are made with fast-on connectors J16,
J17, and J18. They are located along the back edge of the board, and
are labeled Phase A, Phase B, and Phase C. Power requirements are
met with a 12-volt power supply that has a 10- to 16-volt tolerance.
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Fast-on connectors J19 and J20 are used for the power supply. J19 is
labeled +12V and is located on the back edge of the board. J20 is
labeled 0V and is located along the front edge. Current measuring
circuitry is set up for 50 amps full scale. Both bus and phase leg currents
are measured. A cycle by cycle overcurrent trip point is set at 46 amps.
Freescale Semiconductor, Inc...
The LV BLDC power stage has both a printed circuit board and a power
substrate. The printed circuit board contains MOSFET gate drive
circuits, analog signal conditioning, low-voltage power supplies, and
some of the large passive power components. This board also has a
68HC705JJ7 microcontroller used for board configuration and
identification. All of the power electronics that need to dissipate heat are
mounted on the power substrate. This substrate includes the power
MOSFETs, brake resistors, current-sensing resistors, bus capacitors,
and temperature sensing diodes. Figure 3-4 shows a block diagram.
POWER
INPUT
BIAS
POWER
BRAKE
MOSFET
POWER MODULE
SIGNALS
TO/FROM
CONTROL
BOARD
GATE
DRIVERS
TO
MOTOR
PHASE CURRENT
PHASE VOLTAGE
BUS CURRENT
BUS VOLTAGE
MONITOR
BOARD
ID BLOCK
ZERO CROSS
BACK-EMF SENSE
Figure 3-4. Block Diagram
The electrical characteristics in Table 3-2 apply to operation at 25°C with
a 12-Vdc supply voltage.
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EVM Motor Board
Table 3-2. Electrical Characteristics of the
3-Ph BLDC Low Voltage Power Stage
Symb
ol
Min
Typ
Max
Units
Motor Supply Voltage
Vac
10
12
16
V
Quiescent current
ICC
—
175
—
mA
Min logic 1 input voltage
VIH
2.0
—
—
V
Max logic 0 input voltage
VIL
—
—
0.8
V
VOut
0
—
3.3
V
Bus current sense voltage
ISense
—
33
—
mV/A
Bus voltage sense voltage
VBus
—
60
—
mV/V
IPK
—
—
46
A
Continuous output current
IRMS
—
—
30
A
Brake resistor dissipation
(continuous)
PBK
—
—
50
W
Brake resistor dissipation
(15 sec pk)
PBK(Pk
—
—
100
W
—
—
85
W
Freescale Semiconductor, Inc...
Characteristic
Analog output range
Peak output current
(300 ms)
Total power dissipation
)
Pdiss
3.5 EVM Motor Board
Motorola’s embedded motion control series EVM motor board is a
12-volt, 4-amp, surface-mount power stage that is shipped with an MCG
IB23810-H1 brushless dc motor. In combination with one of the
embedded motion control series control boards, it provides a software
development platform that allows algorithms to be written and tested
without the need to design and build a power stage. It supports
algorithms that use Hall sensors, encoder feedback, and back EMF
(electromotive force) signals for sensorless control.
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The EVM motor board does not have overcurrent protection that is
independent of the control board, so some care in its setup and use is
required if a lower impedance motor is used. With the motor that is
supplied in the kit, the power output stage will withstand a full-stall
condition without the need for overcurrent protection. Current measuring
circuitry is set up for 4 amps full scale. In a 25οC ambient operation at up
to 6 amps continuous RMS output current is within the board’s thermal
limits.
Freescale Semiconductor, Inc...
Input connections are made via 40-pin ribbon cable connector J1. Power
connections to the motor are made on output connector J2. Phase A,
phase B, and phase C are labeled on the board. Power requirements are
met with a single external 12-Vdc, 4-amp power supply. Two connectors,
labeled J3 and J4, are provided for the 12-volt power supply. J3 and J4
are located on the front edge of the board. Power is supplied to one or
the other, but not both. The electrical characteristics in Table 3-3 apply
to operation at 25°C and a 12-Vdc power supply voltage.
Table 3-3. Electrical Characteristics of the EVM Motor Board
Symb
ol
Min
Typ
Max
Units
Power Supply Voltage
Vdc
10
12
16
V
Quiescent Current
ICC
—
50
—
mA
Min Logic 1 Input Voltage
VIH
2.4
—
—
V
Max Logic 0 Input Voltage
VIL
—
—
0.8
V
Input Resistance
RIn
—
10
—
kΩ
Analog Output Range
VOut
0
—
3.3
V
Bus Current Sense Voltage
ISense
—
412
—
mV/A
Bus Voltage Sense Voltage
VBus
—
206
—
mV/V
Power MOSFET On
Resistance
RDS(O
—
32
40
MΩ
RMS Output Current
IM
—
—
6
A
Pdiss
—
—
5
W
Characteristic
Total Power Dissipation
n)
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Optoisolation Board
The EVM Motor Board is shipped with an MCG IB23810-H1 brushless
dc motor. The motor characteristics in Table 3-4 apply to operation at
25°C.
Table 3-4. Characteristics of the BLDC motor
Characteristic
Freescale Semiconductor, Inc...
Terminal Voltage
Symb
ol
Min
Typ
Max
Units
Vt
—
—
60
V
—
5000
—
RPM
Speed @ Vt
Torque Constant
Kt
—
0.08
—
Nm/A
Voltage Constant
Ke
—
8.4
—
V/kRP
M
Winding Resistance
Rt
—
2.8
—
Ω
Winding Inductance
L
—
8.6
—
mH
Continuous Current
Ics
—
—
2
A
Peak Current
Ips
—
—
5.9
A
Inertia
Jm
—
0.075
—
kgcm2
—
—
3.6
°C/W
Thermal Resistance
3.6 Optoisolation Board
Motorola’s embedded motion control series optoisolation board links
signals from a controller to a high-voltage power stage. The board
isolates the controller, and peripherals that may be attached to the
controller, from dangerous voltages that are present on the power stage.
The optoisolation board’s galvanic isolation barrier also isolates control
signals from high noise in the power stage and provides a noise-robust
systems architecture.
Signal translation is virtually one-for-one. Gate drive signals are passed
from controller to power stage via high-speed, high dv/dt, digital
optocouplers. Analog feedback signals are passed back through
HCNR201 high-linearity analog optocouplers. Delay times are typically
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250 ns for digital signals, and 2 µs for analog signals. Grounds are
separated by the optocouplers’ galvanic isolation barrier.
Freescale Semiconductor, Inc...
Both input and output connections are made via 40-pin ribbon cable
connectors. The pin assignments for both connectors are the same. For
example, signal PWM_AT appears on pin 1 of the input connector and
also on pin 1 of the output connector. In addition to the usual motor
control signals, an MC68HC705JJ7CDW serves as a serial link, which
allows controller software to identify the power board.
Power requirements for controller side circuitry are met with a single
external 12-Vdc power supply. Power for power stage side circuitry is
supplied from the power stage through the 40-pin output connector.
The electrical characteristics in Table 3-5 apply to operation at 25°C,
and a 12-Vdc power supply voltage.
Table 3-5. Electrical Characteristics
Characteristic
Symbol
Min
Typ
Max
Units
Notes
Power Supply Voltage
Vdc
10
12
30
V
Quiescent Current
ICC
70(1)
200(2)
500(3)
mA
dc/dc converter
Min Logic 1 Input Voltage
VIH
2.0
—
—
V
HCT logic
Max Logic 0 Input Voltage
VIL
—
—
0.8
V
HCT logic
Analog Input Range
VIn
0
—
3.3
V
Input Resistance
RIn
—
10
—
kΩ
Analog Output Range
VOut
0
—
3.3
V
Digital Delay Time
tDDLY
—
0.25
—
µs
Analog Delay Time
tADLY
—
2
—
µs
1. Power supply powers optoisolation board only.
2. Current consumption of optoisolation board plus DSP EMV board (powered from this power supply)
3. Maximum current handled by dc/dc converters
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3-Phase AC BLDC High Voltage Power Stage
3.7 3-Phase AC BLDC High Voltage Power Stage
Freescale Semiconductor, Inc...
Motorola’s embedded motion control series high-voltage (HV) ac power
stage is a 180-watt (one-fourth horsepower), 3-phase power stage that
will operate off of dc input voltages from 140 to 230 volts and ac line
voltages from 100 to 240 volts. In combination with one of the embedded
motion control series control boards and an optoisolation board, it
provides a software development platform that allows algorithms to be
written and tested without the need to design and build a power stage. It
supports a wide variety of algorithms for both ac induction and brushless
dc (BLDC) motors.
Input connections are made via 40-pin ribbon cable connector J14.
Power connections to the motor are made on output connector J13.
Phase A, phase B, and phase C are labeled PH_A, Ph_B, and Ph_C on
the board. Power requirements are met with a single external 140- to
230-volt dc power supply or an ac line voltage. Either input is supplied
through connector J11. Current measuring circuitry is set up for 2.93
amps full scale. Both bus and phase leg currents are measured. A
cycle-by-cycle over-current trip point is set at 2.69 amps.
The high-voltage ac power stage has both a printed circuit board and a
power substrate. The printed circuit board contains IGBT gate drive
circuits, analog signal conditioning, low-voltage power supplies, power
factor control circuitry, and some of the large, passive, power
components. All of the power electronics which need to dissipate heat
are mounted on the power substrate. This substrate includes the power
IGBTs, brake resistors, current sensing resistors, a power factor
correction MOSFET, and temperature sensing diodes. Figure 3-4
shows a block diagram.
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HV POWER
INPUT
SWITCH MODE
POWER SUPPLY
3-PHASE IGBT
POWER MODULE
SIGNALS
TO/FROM
CONTROL
BOARD
Freescale Semiconductor, Inc...
PFC CONTROL
dc BUS BRAKE
3-PHASE AC
TO
MOTOR
GATE
DRIVERS
PHASE CURRENT
PHASE VOLTAGE
BUS CURRENT
BUS VOLTAGE
MONITOR
BOARD
ID BLOCK
ZERO CROSS
BACK-EMF SENSE
Figure 3-5. 3-Phase AC High Voltage Power Stage
The electrical characteristics in Table 3-6 apply to operation at 25°C with
a 160-Vdc power supply voltage.
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Hardware Documentation
Table 3-6. Electrical Characteristics of Power Stage
Freescale Semiconductor, Inc...
Characteristic
Symbol
Min
Typ
Max
Units
dc input voltage
Vdc
140
160
230
V
ac input voltage
Vac
100
208
240
V
Quiescent current
ICC
—
70
—
mA
Min logic 1 input voltage
VIH
2.0
—
—
V
Max logic 0 input voltage
VIL
—
—
0.8
V
Input resistance
RIn
—
10 kΩ
—
Analog output range
VOut
0
—
3.3
V
Bus current sense voltage
ISense
—
563
—
mV/A
Bus voltage sense voltage
VBus
—
8.09
—
mV/V
Peak output current
IPK
—
—
2.8
A
Brake resistor dissipation
(continuous)
PBK
—
—
50
W
Brake resistor dissipation
(15 sec pk)
PBK(Pk)
—
—
100
W
Pdiss
—
—
85
W
Total power dissipation
3.8 Hardware Documentation
All the system parts are supplied and documented according to the
following references:
•
U1 - MC68HC908MR32 Control Board:
– supplied as: ECCTR908MR32
– described in: Motorola Embedded Motion Control
MC68HC908MR32 Control Board User’s Manual
MEMCMR32CBUM/D
•
U2 - 3 ph AC/BLDC Low Voltage Power Stage
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– described in: Motorola Embedded Motion Control 3-Phase
BLDC Low-Voltage Power Stage User’s Manual
MEMC3PBLDCLVUM/D
•
or - Evaluation Motor Board
– described in: Motorola Embedded Motion Control Evaluation
Motor Board User’s Manual
•
or - 3 ph AC/BLDC High Voltage Power Stage
Freescale Semiconductor, Inc...
– supplied in kit with Optoisolation Board as:
ECOPTHIVACBLDC
– described in: Motorola Embedded Motion Control 3-Phase AC
BLDC High-Voltage Power Stage User’s Manual
MEMC3PBLDCPSUM/D
•
U4 - Optoisolation Board
– supplied with 3 ph AC/BLDC High Voltage Power Stage as:
ECOPTHIVACBLDC
– or supplied alone as: ECOPT - optoisolation board
– described in: Motorola Embedded Motion Optoisolation Board
User’s Manual MEMCOBUM/D
Detailed descriptions of individual boards can be found in
comprehensive User’s Manuals belonging to each board. The manuals
are available on the Motorola web. The User’s Manual incorporates the
schematic of the board, description of individual function blocks and a bill
of materials. An individual board can be ordered from Motorola as a
standard product.
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Section 4. Software Design
Freescale Semiconductor, Inc...
4.1 Contents
4.2
Software Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.3
Software Data Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4
Software Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.5
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
4.6
Main Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.7
Application Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.8
PC Master Software (Remote) Operating Mode. . . . . . . . . . . . 45
4.2 Software Design
This section describes the design process of control algorithm, and of
the software blocks implemented in the drive.
4.3 Software Data Flow
The control algorithm of closed loop drive for the 3-Phase BLDC Motor
with Hall sensors is described in Figure 4-1. The inputs are desired
omega from speed pot (Manual Control), or from external control (SCI)
and Hall sensor signals (Hall Sensors). The output is a three phase
PWM signal (PWM Generation).
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Manual
Control
SCI
Hall
Sensor
PC master process
Sensor Edge
Detection
Rotor Position
Detection
Period Calculation
omega_desired
rotorPosition
Freescale Semiconductor, Inc...
SensorPhasePeriod
Speed Ramp
Speed Calculation
omega_reqRMP_mech
omega_actual_mech
Speed Controller
speedControllerOutput
Motor Voltage
Calculation
Commutation Delay
Calculation
CommutationDelay
Commutation
u_phase
vectorActual
Voltage Vector
Generation
PWM
Generation
Figure 4-1. Main Data Flow
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Software Processes
4.4 Software Processes
Freescale Semiconductor, Inc...
4.4.1 PC Master Process
A small program is resident in the MR32 that communicates with the PC
master software running on the PC. It controls data exchange between
the application and the Serial Communication Interface (SCI). The
module enables read and write to the CPU RAM and reading the whole
CPU memory. It provides a remote control interface to the application.
For control actions provided see section 4.8 PC Master Software
(Remote) Operating Mode.
4.4.2 Sensor Edge Detection
Each incoming edge on the signal from Hall sensors causes an interrupt
on channel 2 of timer A. The interrupt routine provides a calculation of a
commutation period, detection of a rotor position and it handles
commutation.
4.4.3 Period Calculation
Period calculation is executed in the interrupt routine called by input
capture interrupt on channel 2 of Timer A. The captured value from the
timer A channel register is read. The commutation period is calculated
as a difference between actual and last captured values. Since the three
phase motor is used, the three last periods are add to eliminate angle
error between the sensors. Then using of edges from same sensor is
secured for speed calculation. The actual captured valued is stored for
period calculation in next interrupt call.
4.4.4 Rotor Position Detection
Rotor position detection is executed in the interrupt routine called by
input capture interrupt on the channel 2 of Timer A. It reads the current
state of the Hall sensors. These sensors comprise six states (001, 010,
011, 100, 101, 110). Each state corresponds to actual rotor position.
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The value of sensors state is used as a pointer to the vector table
see Table 2-1, which is used to determine actual rotor position.
The actual rotor position is compared with the position in the last call and
the direction of rotation is determined.
4.4.5 Speed Calculation
Freescale Semiconductor, Inc...
The measured speed omega_actual_mech is calculated every 10ms
in the overflow interrupt of timer B (EQ 4-1.).
speedScale
omega_actual_mech = -----------------------------------------------CommutationPeriod
(EQ 4-1.)
where
•
speedScale is a constant representing the speed scale and the
number of pole pairs.
•
CommutationPeriod is the Hall sensors period
The measured speed can be updated only when the edge on the Hall
sensor signal is detected. The long distance between the Hall sensor
signal edges in the motor speeds could cause speed fluctuations of the
motor.
4.4.6 Speed Controller
The scaled PI controller is used for the speed closed loop. The controller
is called every 10ms. Actual and required speed are inputs to the
controller. Output of the controller sets the level of voltage applied to the
motor. The controller constants were tuned experimentally. Because the
speed update depends on actual motor speed, the speed controller
constants have to be changed according to the maximum measured
speed, to achieve the best result.
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Software Processes
4.4.7 Speed Ramp
The Speed Ramp decreases the rate of required speed variation. It is
called every 10 ms. The maximum rate of change is determined by a
variable called speedIncrement.
4.4.8 Commutation Algorithm
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This algorithm performs BLDC motor commutation. Based on the
scanned actual rotor position it calculates new voltage vector angle.
With six-step control we get a total of six possible stator flux vectors. The
stator flux vector must be changed at a certain rotor position. The Hall
sensors generate three signals that also comprise six states. Each of
Hall sensors’ states corresponds to certain stator flux vector.
The algorithm differs for commutation when the motor is fully excited, i.e.
motor speed is below nominal value, and when the de-excitation is
performed, i.e. field weakening region.
When the motor is fully excited it is necessary to keep the angle between
stator and rotor flux close to 90° for proper operation. To control speed
of the motor we are adjusting d.c. voltage level applied to the motor. This
control technique is called “a voltage control”.
The commutation is repeated per each 60 electrical degrees. That
means there is no possibility of keeping the angle between the rotor flux
and the stator flux precisely at 90°. From the rotor position the new
voltage vector angle is calculated according to required direction. For
positive direction of rotation 90° is added to the rotor position. For
negative direction 90° is subtracted. According to the calculated angle
appropriate voltage vector is generated (see Table 2-2). Note that the
voltage vectors in the table are shifted 30° from Hall sensor position. As
a result we generate voltage vector shifted 120° from the rotor position.
Then, during the whole period the angle of voltage vector remains
unchanged. That means the real angle varies from 60° to 120°.
A field weakening of the motor may be required to extend the full speed
range. The BLDC motor can be field-weakened by increasing the angle
between motor voltage and rotor flux. If the motor is de-excited
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advancing of the voltage vector is required. In de-excitation, speed of the
motor is controlled by adjusting the voltage vector angle. The level of d.c.
voltage applied to the motor remains constant. In this case the voltage
vector is advanced 150° from the rotor position and applied with
appropriate delay. The delay is made by preset counter on channel 0 of
timer A. This control technique is called “an angle control”.
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4.4.9 Commutation Delay Calculation
This algorithm calculates the CommutationDelay required for
de-excitation. The delay is calculated from the required motor speed.
4.4.10 Motor Voltage Calculation
This algorithm calculates the d.c. voltage level applied to the motor. It is
calculated from the required motor speed. The calculated value is stored
to the variable u_phase.The PWM module is set to run in
complementary center aligned mode. The PWM frequency is 16 kHz.
4.4.11 Voltage Vector Generation
The algorithm writes the required voltage vector to the PWM value
registers. The inputs to the algorithm are required voltage vector angle
and motor voltage level. Based on the inputs appropriate duty cycle
values are written to the PWM value registers.
4.4.12 Under and Over Voltage Protection
The DC bus voltage is scanned using ADC. The sensed value is
compared with minimum and maximum voltage limits. If the limits are
exceeded the fault flag is set.
In case of over voltage an external hardware connected to the FAULT1
pin of the microcontroller provides a rising edge. It causes an FAULT1
interrupt. The interrupt routine disables PWM output and sets a fault flag.
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Interrupts
4.4.13 Over Current Protection
In case of over current an external hardware connected to the FAULT2
pin of the microcontroller provides a rising edge. It causes an FAULT2
interrupt. The interrupt routine disables PWM output and sets a fault flag.
4.5 Interrupts
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The interrupt handlers have the following functions:
•
Timer A, channel 2, input capture - provides a rotor position
detection, commutation period calculation and commutation
process
•
Timer A, channel 0, output on compare - provides a commutation
delay in case of de-excitation.
•
Timer B, overflow - provides a time base, speed calculation, speed
ramp, speed controller, motor voltage calculation, switch
debounce service, LED control and starts the AD conversion.
•
PWM reload - updates PWM value registers with actual values.
•
ADC conversion complete - reads DC Bus voltage and check the
voltage limits
•
PWM fault 1 - handles an over voltage, disables PWM module and
sets the fault flag
•
PWM fault 2 - handles an over current, disables PWM module and
sets the fault flag
•
SCI - PC master software communication
4.6 Main Program
The main program routine is entered after reset. It provides an
initialization of the microcontroller. After initialization the application
enters an infinite background loop, where the application state machine
is executed.
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The application can be in one of four states. The application states are
shown in Figure 4-2.. The diagram shows the states and transition
conditions.
Init State
HW_DETECTED = 1
PC_CHANGE_MODE = 0
START = 0
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FAULT_FLAG = 1
PC_CHANGE_MODE = 1
Fault State
FAULT_FLAG = 1
Stop State
START = 0
START = 1
FAULT_FLAG = 1
Run State
Figure 4-2. Application State Machine Diagram
4.7 Application Initialization
During initialization phase following actions are done:
•
Chip peripherals are initialized (PLL module, PWM module, Timer
modules, ADC module, SCI module, GPIO ports etc.) For
peripheral initialization see appconfig.h file.
•
State of the control board switches is read, used LEDs are
initialized.
•
DC-bus voltage check for undervoltage
•
Hardware identification is done
•
Interrupts are enabled
After initialization the infinite background loop is entered. Application
enters INIT state.
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PC Master Software (Remote) Operating Mode
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In INIT state following actions are done:
•
The application is designed to run with a different motors.
Parameters of the application corresponding to the detected
hardware are set.
•
Request for operation mode is checked
•
Hall sensor Identification is performed if it is allowed.
•
Application waits for start
4.7.1 Hall Sensor Identification
Hall sensor identification can be executed during initialization of the
motor. It is enabled if the switch SW2 - 2 is in ON position.
The sensor identification is done each time before motor is started. The
sensor identification algorithm will make a table with rotor positions
assigned for each Hall sensor code.
If the Hall sensor identification is disabled, the table for a default
arrangement is used.
4.8 PC Master Software (Remote) Operating Mode
The drive is controlled remotely from a PC via an RS-232 physical
interface. The manual control is ignored and all required values are
controlled from PC.
The actions controlled in PC master operating mode are:
•
Start/Stop control
•
Motor speed setpoint
•
Close Loop/Open Loop operation
•
Motor rotation direction control (CW/CCW)
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PC master software displays the following information on a control page:
•
Applied voltage
•
Required voltage
•
Speed
•
Direction
•
RUN/STOP switch status
•
Close Loop/Open Loop operation status
•
Application mode (manual/remote control)
The other variables can be viewed in the variables section.
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Section 5. Application Setup
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5.1 Contents
5.2
Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.3
Hardware Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.4
Software Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.5
Executing the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.2 Warning
This application operates in an environment that includes dangerous
voltages and rotating machinery.
Be aware that the application power stage and optoisolation board are
not electrically isolated from the mains voltage - they are live with risk of
electric shock when touched.
An isolation transformer should be used when operating off an ac power
line. If an isolation transformer is not used, power stage grounds and
oscilloscope grounds are at different potentials, unless the oscilloscope
is floating. Note that probe grounds and, therefore, the case of a floated
oscilloscope are subjected to dangerous voltages.
The user should be aware that:
Before moving scope probes, making connections, etc., it is generally
advisable to power down the high-voltage supply.
To avoid inadvertently touching live parts, use plastic covers.
When high voltage is applied, using only one hand for operating the test
setup minimizes the possibility of electrical shock.
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Operation in lab setups that have grounded tables and/or chairs should
be avoided.
Wearing safety glasses, avoiding ties and jewelry, using shields, and
operation by personnel trained in high-voltage lab techniques are also
advisable.
Power transistors, the PFC coil, and the motor can reach temperatures
hot enough to cause burns.
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When powering down; due to storage in the bus capacitors, dangerous
voltages are present until the power-on LED is off..
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Hardware Setup
5.3 Hardware Setup
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The motor control system is designed to drive the 3-phase BLDC motor
in a speed closed loop using a 68HC908MR32 microcontroller. The
system configuration for low voltage motors consists of:
•
Motorola MC68HC908MR32 control board
•
3-phase BLDC low voltage power stage or EVM motor board
•
3-phase BLDC motor with Hall sensors
•
12 V DC Power supply
•
Serial cables to PC
The system configuration is shown in the Figure 5-1.
40w flat
ribbon
cable
U1
U3
J5
U2
12V DC
J2
Hall sensor cable
M1
U1 – 68HC908MR32 MC Board
U2 –3-Ph Low Voltage BLDC Power Stage or Evaluation
Motor Board
U3 – 68HC908MR32 Daughter Board
M1 – 3 phase BLDC Motor
Figure 5-1. H/W System Configuration for low voltage motor
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The system configuration for high voltage motors consists of:
•
Motorola MC68HC908MR32 control board
•
Optoisolation board
•
3-phase AC/BLDC high voltage power stage
•
3-phase BLDC motor with Hall sensors
•
12V DC Power supply
•
230/115V AC Power Supply
•
Serial cables to PC
The system configuration is shown in the Figure 5-2.
40w flat
ribbon
cable
U1
U4
J5
12 V DC
U2
40w flat
ribbon
cable
U3
230/115 V
AC
J2
Hall sensor cable
M1
U1 – 68HC908MR32 MC Board
U2 –Optoisolation Board
U3 –3-Ph High Voltage AC/BLDC Power Stage
U4 – 68HC908MR32 Daughter Board
M1 – 3 phase BLDC Motor
Figure 5-2. H/W System Configuration for high voltage motor
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Application Setup
Hardware Setup
5.3.1 Controller Board Jumper Settings
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To execute the 3-phase BLDC motor control application with Hall
sensors, the MC68HC908MR32 control board requires the jumper
settings shown in Figure 5-3 and Table 5-1
Figure 5-3. MC68HC908MR32 Jumper Reference
NOTE:
The JP2 jumper must be connected
Table 5-1. MCHC908MR32 Board Jumper Settings
Jumper Group
Comment
JP1
Tacho
JP2
Encoder / Hall Sensor
JP3
BEMF_z_c
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No connection
1–2
No connection
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Table 5-1. MCHC908MR32 Board Jumper Settings
Jumper Group
Comment
Connections
JP4
PFC_z_c
No connection
JP5
PFC_PWM
No connection
JP7
GND_Connection
1–2
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5.4 Software Setup
5.4.1 Required Software Tools
The application requires then following software development tools:
•
Metrowerks1CodeWarrior®2 for MC68HC08 microcontrollers
version 1.2 or later.
•
PC master software version 1.2.0.11 or later
5.4.2 Application Files
The application files are distributed in compressed zip-file:
3ph_bldc_hs_sa.zip. Unconpress the files to the folder on your hard
drive. The 3-phase BLDC motor control application with Hall sensors is
composed of the following files:
•
3ph_bldc_hs_sa.mcp, application project file
•
sources\3ph_bldc_hs.c, main program
•
sources\3ph_bldc_hs.h, main program header file
•
sources\appconfig.h, application configuration file for static
periphery configuration
•
prms\hc908mr32.prm, linker parameters file
1. Metrowerks® and the Metrowerks logo are registered trademarks of Metrowerks, Inc., a wholly
owned subsidiary of Motorola, Inc.
2. CodeWarrior® is a registered trademark of Metrowerks, Inc., a wholly owned subsidiary of
Motorola, Inc.
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Software Setup
•
pcmaster\3ph_bldc_hs.pmp, PC master software file
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Besides the application specific files listed above the application is
distributed with peripheral drivers and algorithms placed in following
folders:
•
config peripheral start-up code
•
drivers and drivers\highlevel - peripheral and high-level drivers
•
algorithms - general motor control algorithms
5.4.3 Building the Application
To build this application, open the 3ph_bldc_hs_sa.mcp project file and
execute the Make command; see Figure 5-4. This will build and link
BLDC motor control application with Hall sensors along with all needed
Metrowerks libraries.
Figure 5-4. Target Build Selection
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5.5 Executing the Application
To execute the 3ph BLDC motor control application with Hall sensors,
select Project\Debug in the CodeWarrior IDE, followed by the Run
command. For more help with these commands, refer to the
CodeWarrior tutorial documentation in the following file located in the
CodeWarrior installation directory:
Freescale Semiconductor, Inc...
<...>\info\CodeWarrior\IDE_User_Guide.pdf
If the MMDS target is selected, CodeWarrior will automatically download
the program to MMDS05/08 emulator.
5.5.1 Application Operating Modes
This 3-phase BLDC motor control application with Hall sensors can
operate in two modes:
1. Manual operating mode
2. PC master software (remote) operating mode
5.5.1.1 Manual Operating Mode
Refer to MC68HC908MR32 control board shown in Figure 5-5 and
Figure 5-6 for this description:
•
START/STOP switch (SW3) - start/stop of the motor
•
SPEED potentiometer (P1) - set motor speed
•
FORWARD/REVERSE switch (SW4) - motor direction control
•
Fault POT Overvoltage - set level of overvoltage fault
•
Fault POT Overcurrent - set level of overcurrent fault
•
Combined switch SW2 functions:
– 1 - open/closed loop operation (ON - closed loop on)
– 2 - Hall sensor identification (ON - identification on)
•
USER LED - indicates status of the drive, for detaliled description
see Table 5-2.
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Application Setup
Executing the Application
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Speed
Speed
potentiometer
Potentiometer
Fault
Fault POT
POT
Over-Voltage
Over-Voltage
Fault POT
POT
Fault
Over-Current
Over-Current
Forward
Reverse
Forward // Reverse
Switch
SW4
switch SW4
Start
Stop
Start / Stop
Switch
SW3
switch SW3
Figure 5-5. MC68HC908MR32 Board - Control Elements
Figure 5-6. USER LEDs, PWM LEDs, and RESET
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Table 5-2. Motor Application States
Application
State
Motor
State
Green
LED State
Yellow
LED State
Red
LED State
Stopped
Stopped
Blinking at a
frequency of 2 Hz
—
—
Running
Spinning
On
—
—
Running
De-excitation
On
On
—
Fault
(under voltage,
sensor fault)
Stopped
Blinking at a
frequency of 8 Hz
—
—
Critical Fault
(over voltage,
over current)
Stopped
Blinking at a
frequency of 8 Hz
—
On
5.5.1.2 PC Master (Remote) Operating Mode
The drive is controlled remotely from a PC via an RS-232 physical
interface. Even if in remote operating mode the drive can be
stopped with RUN/STOP switch on cotroller board. This feature
enables to stop the application safely at any time.
The actions controlled in PC master operating mode are:
•
Start/Stop control
•
Motor speed setpoint
•
Motor rotation direction control (CW/CCW)
•
Close Loop/Open Loop operation
The PC master software displays the following information:
•
Applied voltage
•
Required voltage
•
Actual speed
•
Direction of motor rotation
•
RUN/STOP switch status
•
Close Loop/Open Loop operation status
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Executing the Application
•
Application mode (manual/remote control)
Project files for PC master software are located in:
PC master software file
..\pcmaster\3ph_bldc_hs.pmp
To start the PC master software’s window application
3ph_bldc_hs.pmp
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NOTE:
If the PC master project (.pmp file) is unable to control the application, it
is possible the wrong load map (.map file) has been selected. The PC
master software uses the load map to determine addresses for global
variables being monitored. Once the PC master project has been
launched, this option may be selected in the PC master window under
"Project/Select other Map File Reload".
The PC master software control window is shown in Figure 5-7.
Figure 5-7. PC Master Control Window
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5.5.2 Starting the Motor in Manual Mode
Switch the START/STOP switch to the START position and set the
required speed by the SPEED potentiometers. If successful, the BLDC
motor will be spinning.
Freescale Semiconductor, Inc...
NOTE:
If the START/STOP switch is set to the START position when the
application starts, toggle the START/STOP switch between the STOP
and START positions to enable motor spinning. This is a protection
feature preventing the motor from starting when the application is
executed from CodeWarrior.
You should also see a lighted green LED, indicating the application is
running. If the application is stopped, the green LED will blink at
a frequency of 2 Hz. If a fault occurs, the green LED will blink at a
frequency of 8 Hz.
5.5.2.1 Switch SW2 Function
In manual control mode, the SW2-1 switch on the CPU board (see
Figure 5-6) determines close/open loop (close loop is at position On).
Switch SW2–2 selects Hall sensor identification (identification is enabled
in position On). When Hall sensor identification is enabled the sensor
identification algorithm is run before each start of the motor. The table
with rotor positions assigned for each Hall sensor code is defined. If the
identification is disabled the table for a standard arrangement is used.
5.5.3 Starting the Motor in Remote Control Mode (using PC Master)
To set the PC master control, perform the following steps:
1. The RUN/STOP switch on controller board must be in the STOP
position
2. Check the PC master mode on the PC master control page
3. Enabled the application by setting the RUN/STOP switch on the
controller board to the RUN position
4. Start the motor by pressing the Start PC Master Push Button and
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Executing the Application
stop the motor by releasing the button
5. Set the speed with the bar graph
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6. The motor can be stopped any time with the RUN/STOP switch on
the EVM. When the RUN/STOP switch on the EVM is in the STOP
position, manual mode can be set again by unchecking PC master
mode on the PC master control page.
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Application Setup
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Designer Reference Manual — 3-ph BLDC Drive Control with Hall Sensors
Appendix A. References
1. Brushless DC Motor Control using the MC68HC708MC4, John
Deatherage and Jeff Hunsinger, AN1702/D, Motorola
Freescale Semiconductor, Inc...
2. Design of Brushless Permanent-magnet Motors, J.R. Hendershot
and T.J.E. Miller, Magna Physics Publishing and Clarendon
Press, 1994
3. 68HC908MR32 User’s Manual, Motorola, Inc. (2001),
(order #:MC68HC908MR32/D)
4. Motorola Embedded Motion Control MC68HC908MR32 Control
Board User’s Manual, Inc. (2000)
(order #:MEMCEVMBUM/D)
5. Motorola Embedded Motion Control 3-Phase BLDC Low-Voltage
Power Stage User’s Manual, Inc. (2000) (order #:
MEMC3PBLDCLVUM/D)
6. Motorola Embedded Motion Control Evaluation Motor Board
User’s Manual, Motorola Inc. (2000)
(order #:MEMCEVMBUM/D)
7. Motorola Embedded Motion Control 3-Phase AC BLDC
High-Voltage Power Stage User’s Manual, Motorola, Inc. (2000),
(order #: MEMC3PBLDCPSUM/D)
8. Motorola Embedded Motion Optoisolation Board User’s Manual,
Motorola, Inc. (2000), (order #: MEMCOBUM/D)
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References
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References
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Appendix B. Glossary
AC — Alternating current.
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analogue-to-digital converter (ADC) — The ADC module is an
10-channel, multiplexed-input successive-approximation
analog-to-digital converter.
brush — A component transfering elektrical power from non-rotational
terminals, mounted on the stator, to the rotor
BLDC — Brushless dc motor.
byte — A set of eight bits.
central processor unit (CPU) — The primary functioning unit of any
computer system. The CPU controls the execution of instructions.
clear — To change a bit from logic 1 to logic 0; the opposite of set.
commutation — A process providing the creation of a rotation field by
switching of power transistor (electronic replacement of brush and
commutator)
commutator — A mechanical device alternating DC current in DC
commutator motor and providing rotation of DC commutator motor
comparator — A device that compares the magnitude of two inputs. A
digital comparator defines the equality or relative differences between
two binary numbers.
computer operating properly module (COP) — A counter module that
resets the MCU if allowed to overflow.
COP — Computer Operating Properly timer
DC — Direct Current.
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DT — see “Dead Time (DT)”
Dead Time (DT) — short time that must be inserted between the turning
off of one transistor in the inverter half bridge and turning on of the
complementary transistor due to the limited switching speed of the
transistors.
duty cycle — A ratio of the amount of time the signal is on versus the
time it is off. Duty cycle is usually represented by a percentage.
Freescale Semiconductor, Inc...
GPIO — General Purpose Input/Output.
Hall Sensors - A position sensor giving six defined events (each 60
electrical degrees) per electrical revolution (for 3-phase motor)
interrupt — A temporary break in the sequential execution of a program
to respond to signals from peripheral devices by executing a subroutine.
interrupt request — A signal from a peripheral to the CPU intended to
cause the CPU to execute a subroutine.
input/output (I/O) — Input/output interfaces between a computer
system and the external world. A CPU reads an input to sense the level
of an external signal and writes to an output to change the level on an
external signal.
LED — Lignt Emiting Diode
logic 1 — A voltage level approximately equal to the input power voltage
(VDD).
logic 0 — A voltage level approximately equal to the ground voltage
(VSS).
MCU — Microcontroller unit. See “microcontroller.”
memory map — A pictorial representation of all memory locations in a
computer system.
microcontroller — Microcontroller unit (MCU). A complete computer
system, including a CPU, memory, a clock oscillator, and input/output
(I/O) on a single integrated circuit.
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64
Glossary
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MOTOROLA
Freescale Semiconductor, Inc.
Glossary
modulo counter — A counter that can be programmed to count to any
number from zero to its maximum possible modulus.
PI controller — Proportional-Integral controller.
peripheral — A circuit not under direct CPU control.
phase-locked loop (PLL) — A clock generator circuit in which a voltage
controlled oscillator produces an oscillation which is synchronized to a
reference signal.
Freescale Semiconductor, Inc...
port — A set of wires for communicating with off-chip devices.
program — A set of computer instructions that cause a computer to
perform a desired operation or operations.
PWM — Pulse Width Modulation.
PWM period — The time required for one complete cycle of a PWM
waveform.
read — To copy the contents of a memory location to the accumulator.
register — A circuit that stores a group of bits.
reset — To force a device to a known condition.
RPM — Revolutions per minute.
SCI — See "serial communication interface module (SCI)."
serial communications interface module (SCI) — A module that
supports asynchronous communication.
serial peripheral interface module (SPI) — A module that supports
synchronous communication.
set — To change a bit from logic 0 to logic 1; opposite of clear.
software — Instructions and data that control the operation of a
microcontroller.
software interrupt (SWI) — An instruction that causes an interrupt and
its associated vector fetch.
DRM022 — Rev 1
MOTOROLA
Designer Reference Manual
Glossary
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65
Freescale Semiconductor, Inc.
Glossary
SPI — See "serial peripheral interface module (SPI)."
stack — A portion of RAM reserved for storage of CPU register contents
and subroutine return addresses.
Freescale Semiconductor, Inc...
subroutine — A sequence of instructions to be used more than once in
the course of a program. The last instruction in a subroutine is a return
from subroutine (RTS) instruction. At each place in the main program
where the subroutine instructions are needed, a jump or branch to
subroutine (JSR or BSR) instruction is used to call the subroutine. The
CPU leaves the flow of the main program to execute the instructions in
the subroutine. When the RTS instruction is executed, the CPU returns
to the main program where it left off.
timer — A module used to relate events in a system to a point in time.
variable — A value that changes during the course of program
execution.
waveform — A graphical representation in which the amplitude of a
wave is plotted against time.
word — A set of two bytes (16 bits).
write — The transfer of a byte of data from the CPU to a memory
location.
DRM022 — Rev 1
Designer Reference Manual
66
Glossary
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MOTOROLA
Freescale Semiconductor, Inc...
Freescale Semiconductor, Inc.
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Freescale Semiconductor, Inc.
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