Timers

1
Timers

• Chapter 10

2
Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

3
Timers (cont.)

• Pulse Train Using Interrupts
• Measuring the Period of a Pulse Train Using
  Interrupts
• The Polaroid Ultrasonic Transducer
• An Ultrasonic Tape Measure

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Timer Counter
6
Timer System Control Register
7
Setting the timer count time
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10
68HC11 Timer Registers
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Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

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Pulse Train Example
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Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

23
Input Capture
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Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

28
Pulse Accumulator
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The 74C922 16-Key Encoder
Connect pin 12 to PT7/PAI instead of PJ7
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Pulse Accumulator on a 68HC11
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Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

37
Timing Interrupt Service Routines Traffic Lights
Using Real-time Interrupt
38
Copy TRAFFIC.WHP to TRAFFIC2.WHP
39
Add
Load TRAFFIC2.WHP TEST.SETUP TEST
40
Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

41
A Circular Queue
empty
Containing 2 values
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45
Timers

• The 68HC12 Programmable Timer
• Output Compares
• Input Capture
• Pulse Accumulator
• Timing Interrupt Service Routines
• A Circular Queue Data Structure
• Keypad Interfacing Using Interrupts

46
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48
Timers (cont.)

• Pulse Train Using Interrupts
• Measuring the Period of a Pulse Train Using
  Interrupts
• The Polaroid Ultrasonic Transducer
• An Ultrasonic Tape Measure

49
Pulse Train
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53
Timers (cont.)

• Pulse Train Using Interrupts
• Measuring the Period of a Pulse Train Using
  Interrupts
• The Polaroid Ultrasonic Transducer
• An Ultrasonic Tape Measure

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56
Timers (cont.)

• Pulse Train Using Interrupts
• Measuring the Period of a Pulse Train Using
  Interrupts
• The Polaroid Ultrasonic Transducer
• An Ultrasonic Tape Measure

57
Polaroid Ultrasonic Ranging System
58
Waveforms of Ultrasonic Ranging System
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Exercises
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