System Concept - Motorola M68HC08 Manual

Cap Cap
48Vdc 48Vdc
Filter Filter
= =
MC68HC908QY4 MC68HC908QY4
User Interface User Interface
Speed Speed
Start Start
Command Command
Stop Stop
Speed Speed
Setup Setup
4.2.1 Six-Channel PWM Generation
DRM046 — Rev 0
MOTOROLA
Freescale Semiconductor, Inc.
12V 12V
DC DC
= =
5V 5V
DC DC
Fault Protection Fault Protection
Speed Speed
Speed Speed
Error Error
+ +
Speed Speed
PI PI
Ramp Ramp
Contr. Contr.
- -
Motor Speed Motor Speed
Figure 4-1. System Concept
Six output pins of MC68HC908QY4 are used for control of power
MOSFETs. Since the MC68HC908QY4 accommodates just one timer
with two timer channels, a general purpose I/O pins needs to be used for
the gate signal generation. They are two possibilities of PWM generation
using the general purpose I/O pins:
• Use s/w PWM generation on GPIO
• Use external logic with PWM generation using timer of MCU
The first option enables to generate arbitrary PWMs on individual pins.
The output compare and overflow ISRs of the on-chip timer can serve as
a reference event for the output pin toggle to get the desired PWM
pulses. The outputs are controlled purely by s/w. The advantage is the
simplicity of the hardware where individual pins are connected directly to
3-Phase BLDC Low Voltage Reference Design
For More Information On This Product,
Go to: www.freescale.com
3-Phase BLDC Low Voltage Reference Design
DC-Bus Current DC-Bus Current
Drivers Drivers
Over-Current Fault Over-Current Fault
NAND Logic NAND Logic
PWM PWM
Duty Duty
BLDC BLDC
Cycle Cycle
PWM PWM
State State
Generation Generation
Machine Machine
Speed Speed
Processing Processing
(Input capture) (Input capture)
Application Description
3-ph 3-ph
HS HS
BLDC BLDC
Gate PWM Gate PWM
PWM's PWM's
Hall Hall
Sensor Sensor
Signals Signals
Commutation Commutation
Vector Vector
A A
B B
C C
Designer Reference Manual
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