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AbstractThis application note describes a controller for a 200 W, 24 V Brushless DC (BLDC)motor used to power an e-bike (i.e., electric bicycle). The design uses ZilogsZ8FMC16100 MCU and associated circuitry to implement motoring control, regenerative

braking, and fault protection.

The source code file associated with this application note, AN0260-SC01.zip , is availablefor download on zilog.com. This source code has been tested with version 5.0.0 of ZDS IIfor Z8 Encore! XP MCUs. Subsequent releases of ZDS II may require you to modify thecode supplied with this application note.

FeaturesThe main features of this high-torque motor control application include:

Hall sensor commutation

Motor speed measurement

Potentiometer-adjustable motor speed

Open-loop or closed-loop speed control for precise speed regulation

Protection logic for over-voltage, over-current, and thermal protection.

DiscussionThe Z8FMC16100 MCU features a flexible Pulse Width Modulation (PWM) module withthree complementary pairs or six independent PWM outputs supporting dead-band opera-tion and fault protection trip input. These features provide multiphase control capabilityfor a variety of motor types and ensure safe operation of the motor by providing pulse-by-

pulse or latched fast shutdown of the PWM pins during fault condition.

The Z8FMC16100 MCU features up to eight single-ended channels of 10-bit analog-to-digital conversion (ADC), with a sample and hold circuit. It also features one operationalamplifier for current sampling and one comparator for over-current limiting or shutdown.

A high-speed ADC enables voltage and current sensing, while dual-edge interrupts and a16-bit timer provide a Hall-effect sensor interface.

A full-duplex 9-bit UART provides serial, asynchronous communication and supports anoption for the Local Interconnect Network (LIN) serial communications protocol. The

Note:

Application Note

AN026004-0413

Electric Bike BLDC Hub MotorControl Using the Z8FMC16100MCU
http://www.zilog.com/docs/appnotes/an0260-sc01.ziphttp://www.zilog.com/docs/appnotes/an0260-sc01.zip

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Electric Bike BLDC Hub Moto r Contr ol Usin g the Z8FMC16100 MCU Appl icati on Not e

LIN bus is a cost-efficient single Master, multiple Slave organization that supports speedup to 20 kbps.

The Z8FMC16100 MCU has a rich set of peripherals and other features such as: additional16-bit timer with capture/compare/PWM capability, SPI, and I 2C Master/ Slave for serialcommunication, and an internal precision oscillator.

The single-pin debugger and programming interface simplifies code development andallows easy in-circuit programming.

A block diagram of the Z8FMC16100 MCU is shown in Figure 1 .

Figur e 1. Z8FMC16100 MCU Block Diagram

Braking and Regenerative ChargingIn this e-bike application, the Z8FMC16100 MCUs PWM registers are configured tooperate in a complementary PWM mode when applied to an inverter bridge that consistsof six MOSFETs. This complementary PWM mode allows for greater control of the e-

bikes braking and regenerative charging process. The BLDC motor will effectively run ineither a motoring mode or a generative mode .

Generative Mode is achieved when the the applied operating voltage is less than theBEMF voltage produced by the rotating motor. Motoring Mode is achieved when theapplied voltage is equal to or greater than the BEMF voltage produced by the rotatingmotor. Varying the applied operating voltage can be accomplished by changing the dutycycle for each phase in the inverter bridge.

For quicker braking, the lower MOSFET devices of the inverter bridge are turned on whilethe upper MOSFETs are turned off, thereby quickly producing a negative current (i.e., anegative torque) to stop the motor. To gain a regenerative charge, the upper MOSFETs are

12-Bit PWMModule for

Motor Control

16-Bit TimerCapture/

Compare/PWM

Operational Amplifier

Up to 16 KBFlash

20 MHzeZ8 CPU

8-Channel10-Bit ADC

512 B SRAM VBO/PORand Reset

ControlI2C, SPI, and

UART with LIN

WatchdogTimer

Single-PinDebugger

InternalPrecisionOscillator

Comparator Interrupt Controller

17 General Purpose I/O Pins

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turned on to allow current flow back to the battery, while the lower MOSFETs are turnedoff.

Hardware ArchitectureIn a Brushed DC motor, commutation is controlled by brush position. In a BLDC motor,however, commutation is controlled by the supporting circuitry. The rotor's position musttherefore be fed back to the supporting circuitry to enable proper commutation.

Two different techniques can be used to determine rotor position:

Hall Sensor-Based Commutation . In the Hall sensor technique, three Hall sensors are placed inside the motor, spaced 120 degrees apart. Each Hall sensor provides either a Highor Low output based on the polarity of magnetic pole close to it. Rotor position is deter-mined by analyzing the outputs of all three Hall sensors. Based on the output from hallsensors, the voltages to the motor's three phases are switched.

The advantage of Hall sensor-based commutation is that the control algorithm is simpleand easy to understand. Hall sensor-based commutation can also be used to run the motorat very low speeds. The disadvantages are that its implementation requires both separateHall sensors inside the motor housing and additional hardware for sensor interface.

Sensorl ess Commutation. In the sensorless commutation technique, the back-EMFinduced in the idle phase is used to determine the moment of commutation. When theinduced idle-phase back-EMF equals one-half of the DC bus voltage, commutation iscomplete.

The advantage of sensorless commutation is that it makes the hardware design simpler. Nosensors or associated interface circuitry are required. The disadvantages are that it requires

a relatively complex control algorithm and, when the magnitude of induced back-EMF islow, it does not support low motor speeds.

When a BLDC motor application requires high torque, when the motor is running at lowspeed, or when the motor is moving from a standstill, the Hall sensor commutation tech-nique is an appropriate choice. A motor used in an electric bicycle application, for exam-

ple, requires high initial torque and is a perfect application for Hall sensor commutation.

Furthermore, two voltage application techniques can be applied, based on the configura-tion of the supply-to-motor windings:

Sinusoidal. Sinusoidal voltage is continuously applied to the three phases. Sinusoidalvoltage provides a smooth motor rotation and fewer ripples.

Trapezoidal. DC voltage is applied to two phases at a time, and the third phase remainsidle. Trapezoidal voltage is less complex to implement. The idle phase is generating theBEMF from the rotating magnet that passes the unenergized idle phase and provides theBEMF zero-crossing data.

How Hall Sensor Commutation Works

To better understand how Hall sensor commutation works, let's look at how it's imple-mented with a two-pole motor. Six different commutation states are required to turn therotor one revolution. The motors commutation states are shown in Figure 2 .

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Table 1 indicates the relationship between the Hall sensor output and phase switching opera-tions shown in Figure 2 .

Table 2 lists the rating of the motor used to develop this application.

Additionally, the application uses a 3-amp High Rupturing Capacity (HRC) fuse.

Table 1. Relationship Between Hall Sensor Output and Phase Switch ing

State Hall A Hall B Hall C Phase B Phase C Phase A

1 0 1 1 0 +V DC V DC2 0 0 1 +V DC 0 V DC3 1 0 1 +V DC VDC 0

4 0 1 0 0 V DC +VDC5 1 1 0 V DC 0 +V DC6 1 0 0 V DC +VDC 0

Table 2. Motor Rating for Electri c Bike BLDC Motor Contro l Appl ication

Type of Motor Linix BLDC

Power Rating 30 W

Speed 3200 RPM

Number of poles 6

Voltage 24 V

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Using the Z8FMC16100 MCU in an Electric Bike BLDC MotorController

Figure 3 offers a visual overview of the electric bike BLDC motor controller. For moredetails about hardware connections, see Appendix A. Schematics on page 12 .

Hardware ArchitectureThe design involves running the BLDC motor in a closed loop or an open loop, with speedas set by a potentiometer. As shown in the architecture diagram, the design generatesPWM voltage via the Z8FMC16100 MCUs PWM module to run the BLDC motor.

After the motor is running, the states of the three Hall sensors change based on the rotor position. Voltage to each of the three motor phases is switched based on the state of thesensors (commutation). Hall sensor interrupts capture timer ticks every sixty degrees to

Figure 3. Electric Bike BLDC Motor Controll er Block Diagram

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measure the rotor speed of the motor. Other peripheral functions can be used to protect thesystem in case of overload, undervoltage, and overtemperature.

The hardware is described in the following sections.

Three-Phase Bridge MOSFET

The three-phase bridge MOSFET consists of six MOSFETs connected in bridge fashionused to drive the three phases of the BLDC motor. The DC bus is maintained at 24 V,which is same as voltage rating of BLDC motor. A separate Hi-Lo gate driver is used foreach high- and low-side MOSFET phase pair, making the hardware design simpler androbust. The high-side MOSFET is driven by charging the bootstrap capacitor.

The DC bus voltage is monitored by reducing it to suitable value using a potential divider.The DC bus current is monitored by putting a shunt in the DC return path. An NTC-typetemperature sensor is mounted on MOSFET heat sink, providing analog voltage output

proportional to temperature.

PWM Module

The Z8FMC16100 MCU contains a six-channel, 12-bit PWM module configured in thisapplication to run in Complementary Mode. The switching frequency is set to 20 KHz.The output on the PWM outputs is controlled according to the inputs from the Hall sen-sors.

The inputs from the Hall sensors determine the sequence in which the three-phase bridgeMOSFET is switched. The Duty cycle of the PWM is directly proportional to the acceler-ator potentiometer input. The change in the duty cycle controls the current through themotor winding, thereby controlling motor torque.

Commutation Logic

The Hall sensors are connected to ports PB0, PB1 and PB2 on the Z8FMC16100 MCU.An interrupt is generated when the input state on any pin changes. An interrupt serviceroutine checks the state of all three pins and accordingly switches the voltage for the three

phases of the motor.

Trapezoidal commutation is used for this application to make implementation simple. Inthis process of commutation, any two phases are connected across the DC bus by switch-ing the top MOSFET of one phase and bottom MOSFET of another phase ON. The third

phase is left un-energized (both top and bottom MOSFET of that phase are switchedOFF).

Speed Measurement

The Hall sensor outputs are connected to to ports PB0, PB1 and PB2. One out of three Hallsensors is used to capture the Timer0 ticks, which represent the actual Hall period forclosed loop calculations.

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Closed Loop Speed Contro l

Closed-loop speed control is implemented using a PI loop, which works by reducing theerror between the speed set by the potentiometer and actual motor speed. The output ofthis PI loop changes the duty cycle of the PWM module, thereby changing the averagevoltage to the motor, and ultimately changing the power input. The PI loop adjusts thespeed at the same rate as the Hall frequency from one of three Hall sensors. In this applica-tion, Open Loop operation is selected in the software by default because any rider of the e-

bike will control the speed of the bike.

Protection Logic

The ADC module periodically checks DC bus voltage, DC bus current, and heat sink temperature. If these values go beyond the set limits, the motor is shut down. These checks aretimed by Timer0 interrupt.

Over-Current Hardware Protection

The Z8FMC16100 MCU has a built-in comparator that is used to shut down the PWM forover-current protection. When the current exceeds the set threshold, a PWM ComparatorFault is generated to turn OFF the PWM Module.

Software ImplementationDuring implementation of the software, the following actions are performed:

Initialization. Hardware modules are initialized for the following functions:

Switch from internal to external oscillator for system operation

Enable alternate function on respective pins for ADC, Comparator, UART, PA6 asGPIO configured to drive LED

Configure Timer0 to run in Continuous Mode to capture the Hall period timing

Configure the comparator to shut down the PWM module when an overcurrent results

Enable the Op Amp to measure the DC bus current flowing to the motor

Configure the ADC to read analog values such as DC bus voltage, current, temperature,and acceleration potentiometer (only one channel at a time)

Configure the PWM module for the individual mode of operation with a 20 kHz switch-ing frequency, control output depending on the values in the PWMOUT Register, and

drive the PWMOUT as defaulted to a low off state at Power-On Reset and at any Reset Configure the Reset/Fault0 pin functions as a Fault0 function

Write-protect Flash memory

Enable Open Loop operation (shown in the main.h file)

Hardware control of the application, with the UART disabled

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Interrupt. The Port B interrupt controls commutation. The Hall sensor output is read on pins PB0:2, the software performs its filtering operation, and the switching sequence of

the MOSFET is determined. The PWM timer interrupt is used to time periodically occur-ring tasks and for the background loop to read analog values from different channels andaverage these values, update the LED indicator status, and update the read parameters onthe UART.

For a visual representation of the application, see Appendix B. Flowcharts on page 17 .

Testing/Demonstrating the ApplicationThis section presents a list of the equipment used and procedures observed to test this e-

bike application.

Equipment Used

Testing for this application was conducted using the following equipment:

Z8FMC16100 Series Motor Control Development Kit

Tektronix digital oscilloscope

Fluke multimeter

30 W BLDC motor

24 V 7 Ah battery

Tektronix power supply

System Configuration

The system requirements on your PC are as follows:

Windows 7 OS

ZDS II version 5.0.0 installed

Optically isolated USB smart cable for program download and debugging

Procedure

Observe the following steps to test the BLDC motor:

1. On the Zilog MC MDS Board, configure the following jumpers:

a. Shunt the 12 positions on J4, J5, and J6 b. Shunt J2 and J3

2. Set the R7 potentiometer on MC MDS Board (99C0987; contained in theZ8FMC16100 Series Motor Control Development Kit) to the middle position to startthe motor.

3. Connect the following wires from the motor to the 3-Phase Motor Control ApplicationBoard (contained in the Z8FMC16100 Series Motor Control Development Kit but notshown in the schematic).

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a. Connect the heavy-gauge blue wire to Motor Phase A (P1) b. Connect the heavy-gauge green wire to Motor Phase B (P2)

c. Connect the heavy-gauge white wire to Motor Phase C (P3)

4. Connect the following wires from the motor to the MC MDS Board (contained in theZ8FMC16100 Series Motor Control Development Kit but not shown in the sche-matic).a. Connect the Hall Sensor-C light gauge blue wire to PB2 at J1 pin 6 with additional

added 680 pF ceramic capacitor to GND. b. Connect the Hall Sensor-B light gauge green wire to PB1 at J1 pin 4 with addi-

tional added 680 pF ceramic capacitor to GND.

c. Connect the Hall Sensor-A light gauge white wire to PB0 at J1 pin 2 with addi-tional added 680 pF ceramic capacitor to GND.

d. Connect the light gauge black wire (Sensor Power Ground) to GND at TP1.e. Connect the light gauge red wire (Sensor Power V CC ) to V CC (3.3V) at TP2.

5. Connect the oscilloscope across the motor terminals.

6. Connect the motor control board to the 24 V power supply.

7. Build the code on ZDS II v5.0.0 and download the code through USB smart cable.

8. Measure the performance of motor at different loads, for each speed setting of the potentiometer.

9. Record the readings and carry out the process for each step in the test sequence.

Test Results

Laboratory performance test of BLDC motor is as follows:

1. Minimum motor speed: 800 RPM

2. Maximum motor speed: 3200 RPM

3. Power consumption: 6 W at 3200 RPM (no load)

4. Regenerative Current at 200 RPM: 350 mA

Future ImplementationThe application discussed in this document covers the motoring and regenerative brakingfeatures for a BLDC hub motor used in an electric bike. Further improvements can bemade to the design by adding the following features:

Controlled charging of SLA batteries by plugging to the AC Mains adaptor

Implementing Torque-boost functionality (through a push-switch), which will give a boost to motor performance

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Utilizing LIN/UART communication to create a dashboard display of measured parameters (speed, Battery voltage, Current, and Fault conditions)

ReferencesThe following supporting documents are available free for download from the Zilog web-site.

eZ8 CPU User Manual (UM0128)

Z8FMC16100 Series Product Specification (PS0246)

PID Motor Control with the Z8PE003 Application Note (AN0030)

Z8 Encore!-Based SLA Battery Charger Application Note (AN0223)

Sensorless Brushless DC Motor Control with Z8 Encore! MC Microcontrollers (AN0226)

Z8 Encore! XP-Based BLDC Fan Control A pplication Note (AN0228)
http://www.zilog.com/docs/um0128.pdfhttp://www.zilog.com/docs/um0128.pdfhttp://www.zilog.com/docs/z8encoremc/ps0246.pdfhttp://www.zilog.com/docs/z8encoremc/ps0246.pdfhttp://www.zilog.com/docs/z8/appnotes/pid_motor_control.pdfhttp://www.zilog.com/docs/z8/appnotes/pid_motor_control.pdfhttp://www.zilog.com/docs/z8encorexp/appnotes/an0223.pdfhttp://www.zilog.com/docs/z8encorexp/appnotes/an0223.pdfhttp://www.zilog.com/docs/appnotes/an0226.pdfhttp://www.zilog.com/docs/appnotes/an0226.pdfhttp://www.zilog.com/docs/appnotes/an0226.pdfhttp://www.zilog.com/docs/z8encorexp/appnotes/an0228.pdfhttp://www.zilog.com/docs/z8encorexp/appnotes/an0228.pdfhttp://www.zilog.com/docs/z8encorexp/appnotes/an0228.pdfhttp://www.zilog.com/docs/appnotes/an0226.pdfhttp://www.zilog.com/docs/z8encorexp/appnotes/an0223.pdfhttp://www.zilog.com/docs/z8/appnotes/pid_motor_control.pdfhttp://www.zilog.com/docs/um0128.pdfhttp://www.zilog.com/docs/z8encoremc/ps0246.pdf

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Electric Bike BLDC Hub Moto r Contr ol

Appendix A. SchematicsFigures 4 through 8 show schematic representations of each of the applications key blocks.

Figure 4. Electric Bike BLDC Motor Controll er Appli cation Schematic, #1 of 5

3 PHASE POWER STAGE

HEATSINK TEMP SENSOR

B A

96C0960

3 PHASE MOTOR CONTROL APPL

A

Title

r ebmuNtnemucoDeziS

V+

B _ ES AHP A _ ES AHP PHASE_B ES AHPB _ ES AHP

GATE_AH

LB _ ET AGL A _ ET AG

GATE_BHGATE_CH

GATE_CL

+BUS+BUS+BUS+BUS+BUS+BUS+BUS+BUS+BUS+BUSSUB+CDV+ +BUS+BUS+BUS+BUS+BUS+BUS+BUS+BUS+BUS

GND

TH

C

C

TH

C2

0.1uF 50V

Q3

IRFZ48

F1

5A FUSE

Q4

IRFZ48

+ C4

3300uF 50V

R510.00k

R4NTC 10k

R2 10.0k

P2

+ C5

3300uF 50V

P1

Q1

IRFZ48

Q2

IRFZ48

P5

R6150k

P4

C1

0.1uF 50V

R10.100 OHM

R3 10.0k

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GATE DRIVE

BEMF DIVIDERS

12V SUPPLY

96C

3 PHASE MOTOR CONTROL APPL

A

Wednesda June 08 2005

Title

r ebmuNtnemucoDeziS

:etaD

AL

AH

BL

BH

CH

PHASE _A P HAS E_ B PHASE_C

VAVA VBVBVBVB

CL

VCC_33V

VC

+12V

+12V

+12V

+12V

R10150k

C6

10uF

R18

C19

10uF

C11

0.1uF

R12150k R13

R2086.6k

R710.00k

U2

IR2101

1

2

3

4 5

6

7

8VCC

HIN

LIN

COM LO

VS

HO

VB

D3 BAV19

L1

10uH

R15

R14

R910.00k

C14

10uF

C20

68pF

R1110.00k

R16

U1

IR2101

1

2

3

4 5

6

7

8VCC

HIN

LIN

COM LO

VS

HO

VB

D4 BAV19

D2 BAV19

C15

0.1uFU3

IR2101

1

2

3

4 5

6

7

8VCC

HIN

LIN

COM LO

VS

HO

VB

U4

TPS61041

1

2

3

4

5 SW

GND

FB

EN

VIN

R8150k

D1 BAV19

C18

10uF

C7

0.1uF

R17

C10

10uF

R1910.0k

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EC AFRETNIREWOPDESUNU

BH

BL

VCC_33V

A A

VCC_33V

VCC_33V

VC

C

T

VA

V+

CH

CS-

VC

JP1

HEADER 30x2/SM

24681012141618202224262830323436384042444648505254565860

13579

11131517192123252729313335373941434547495153555759

JP2

HEADER 30x2/SM

24681012141618202224262830323436384042444648505254565860

13579

11131517192123252729313335373941434547495153555759

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RUN/ST OP

DIRECT ION

Connect ion between AG ND and GNDshould be done as clo se as po ssibleto the pin 5, AGND.Connection between AVCC and VCC_33Vshould be done as clo se as po ssibleto the pin 4, AVCC.

SPEED

LOCAL/ MDS

ANA4 PA0_OPINN

ANA2_M ANA0_M

PWM2H ANA6

PWM1H

PW M1L

PA2_CINP

PA4_RXDPA6_CTS

VC-RES

VCC

PA1_OP_CN

ANA0 ANA1 ANA2

GND

PA3_TXDE

PA6_CTS

VREF

ANA2_M

ANA1

ANA0

ANA0_M

ANA1_M

ANA2

PA0_OPINN

P A 2_ C I N P

P A 4_ R X D

P W M 2 L

P A 5_ T X D

PWM0H

P W M 2 H

A N A 5

XIN

PA3_TXDE

-RESET

D B G

PC0_T0O UT

- R E S E T

ANA6

P W M 1 L

P B 3_ A N A 3_ O P O U T

A N A 7

P A 6_ C T S

P C 0_ T 0 O U T

VCC_33V

PWM1H

AGND AVCC

VCC_33V

GND

A N A 6

XOUT

PW M0L

P A 7_ C O U

T

A N A 4

DBG

PA5 _TXDPA4_RXD

PA6_CTS

-RESET

VCC_33V

VCC_33V

VCC_33V

S1

SW SPDT

R9 49.9K

J6HEADER 3

1 2 3

C22

100pF

C4

22pF

R10 100

C17

0.01

C23

0.1uF

C20

0.01

R7 5K

1

3

2

R12 10K

R60

D1

RED

2 1

R14

10K

C5

22pF

R241KC18

0.01

C24

0.1uF

R13 10K

R15

10K

Y1

20MHz

1

2

31

2

3

J1

HEADER 5X2

2 4 6 8 1 0

1 3 5 7 9

S2

SW SPDT

C19

0.01

J4HEADER 3

1 2 3

C25

0.1uF

D2

LED YEL

2 1

U1Z8FMC16110_32

12345678

9

2 8

1 1 1 2 1 3 1 4 1 5 1 6

1718192021222324

2 5 2 6 2 7 2 9 3 0 3 1 3 2

1 0

PB2/ANA2/T0IN2PB1/ANA1/T0IN1PB0/ANA0/T0IN0

AVDD AGND

VREFPA0/OPINN

PA1/OPINP/CINN

P A 2 / C I N P

P B 7 / A N A 7

R E S E T / F A U L T 0

D B G

P C 0 / T 0 O U T

P W M 2 L

P W M 2 H

P W M 1 L

PWM1HPWM0LPWM0HGNDXOUTXINVDDPA3/TXDE/SCL

P A 4 / R X D

P A 5 / T X D

P A 6 / C T S / S D A

P B 6 / A N A 6

P B 5 / A N A 5

P B 4 / A N A 4 / C I N N

P B 3 / A N A 3 / O P O U T

P A 7 / F A U L T 1 / T 0 O U T / C O U T

R1 10 0

C1

0.1uF

R23 10K

C6 12pF

R5 10K

J5HEADER 3

1 2 3

R4

10K

C21

100pF

R27.5K

R8 100

C16

0.01

R312.4K

D3

LED GRN

2 1

C2

100pF

C3

1000pF

R11 10K

C26

10uF

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3.3 O K

DIS IRDA

DIS RS232

DBG

INTERF ACE

change pinout

VCC_33V

GNDVCC_33V

VCC_33V

DBG

VCC_33V

-RESET

GND

PA5_TXD

GND

VCC_5V

VCC_33

VCC_33V

PA4_RXD

GND

GND

GND

GND

GND

PA5_TXD

-RESET

PA4_RXD

PA6_CTS

DBG

VCC_33V

-DIS_IRDA

-DIS_232

R17 0

C80.1uF

C100.1uF

U4E

74LVC04/SO

11 10

1 4

7

U4A

74LVC04/SO

1 2

1 4

7

C120.1uF

J2

12

U4D

74LVC04/SO

9 8

1 4

7

P3

Header 3x2

1 23 45 6

R1810K

U4B

74LVC04/SO

3 4

1 4

7

U3SPX2815AU-3.3

3

1

2VI

G N D VO

U4F

74LVC04/SO

13 12

1 4

7

J3

12

R16

68 0

P1

PWR JACK

231

+ C13

100/10C14

0.1uF

R2110K

+ C9

100/10

U4C

74LVC04/SO

5 6

1 4

7

U2

SP32

1

2

4

5

6

13

12

15

10

20

1 9

1 8

EN

C1+

C1-

C2+

C2-

T1IN

T2IN

R1OUT

R2OUT

V

V

T1OUT

T2OUT

R1IN

R2IN

SHDN

V C C

G N D

NCNC

TP1

1 2 3 4 5

D4

LED

2

1

R2210K

TP2

1 2 3 4 5

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Appendix B. Flowcharts

Figure 9 presents a simple flow chart of the main, timer interrupt and Port B interrupt rou-tines for the electric bike BLDC motor controller application.

Figure 9. Electric Bike BLDC Motor Cont roll er Applicatio n Flowchart

Main()

Hall interrupt?

Capture 3 Hallsensor binary

states

Switch into next

commutation state

Hall states = 3? Timer0rollover?

Hall period =0xFFFF

Capture Timer0period and reset

Timer0

Obtain ADC resultfor set-speed used

for open/closedloop

Initialize MCUperipherals

Apply PI controlvalue to PWM

registers

Closed loopselected?

Start

Yes No

Yes No

Yes

Yes

No

No

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