Electronics • Pneumatics • Machiningsinghose.marc.gatech.edu/courses/me2110...

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• Electronics• Pneumatics• Machining

ME 2110 - Creative Decisions & Design

Lecture 9 v.3

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Introduction to the ME 2110 Kit

Controller Box

Pneumatics

Electro Mechanical Actuators & Sensors

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Features of the Controller Box

• BASIC Stamp II-SX microcontroller• Interfaces with various external

devices• Stepper Motors• DC Motors• Pneumatic Valves• IR Distance Sensor• Rotary Encoder• Microswitches• Solenoids

• RS-232 Communication Port

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Layout of I/O Ports

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Electro/Mechanical Supplies

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Sensors

• Micro-switches• Push button switches• Infrared (IR) sensors• Rotary encoders

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Micro-switch

• Lever arm closes circuit

• Status of IN register holds status of port

• 0 = Open Circuit• 1 = Closed Circuit

• Same action is going to start competition

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Push Button Switch

• Latches “on” when depressed

• Must be depressed again to switch off

• Not the exact one supplied in kits – kit one is rectangular

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Infrared Distance Sensor

• 4” to 30” Range• Infrared beam is emitted• Beam reflects off object• Detected by receiver• Output voltage (not

linearly) proportional to distance

• A/D Converter: Reading between 0 and 255

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Rotary Encoder• Rotational motion of shaft

converted to electrical pulses, or counts, that are read by microcontroller.

• The rotational measurement is based upon the number of counts.

• Kit’s encoder is a relative encoder; it only counts relative to its starting position for each count command.

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A/D Converter

• Converts a continuous voltage to a multi-level discrete digital value

• Used with Distance Sensor (0-255)

• Use these values to convert to desired quantities using conversion factors

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A/D Converter

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Using the A/D Converter• Power up chip

• Choose channel

• Serially send a “Take Reading” command

• Serially receive the value

• Power down chip

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Actuators

• Solenoid• DC motor• Stepper motor

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Solenoid• Consists of a coil of wire – Electromagnet• When powered up, pulls in plunger• One way device

• Does not return automatically

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DC Motor• Speed is proportional to

voltage• Moves in both directions

• depends on sign of voltage

• Gearbox to slow down shaft

• Very high torque• Requires time to ramp up

and down

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DC Brush Motor• Fixed Field Magnet• Coils create an

electromagnet• Field magnet rotates

armature• As armature turns,

polarity reverses• Cycle continues• Both directions

N S

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Pulse Width Modulation (PWM)

• Controller box can only send 0 or 5 volts• PWM is used to run motor at intermediate

speeds• PWM uses cycles of pulses

5 Volts

0 Volts

Off On One Cycle

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Stepper Motors• Both motors are

controlled through P10• Speed is a value

chosen between 2 and 240

• Can move both directions

• Amount of motion can be specified

• Negligible ramping time

• Low Power• When off, shaft rotates

freely

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Stepper Motor

• Clockwise rotation shown• Reverse process for counterclockwise

rotation

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Programming the Stamp

• PBASIC (a version of BASIC) is used to program the Stamp

• Everything is global• Variables• Constants• Subroutines

• Programming and commenting style is very important

• Programming syntax is explained in the manual

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Programming EditorSave

Transfer to Controller

BoxRun Motor 1Read EncoderRelease WhackerGrab StuffClose DoorPut Down Weapons

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• Versioning• Keep old versions of your programs• Do not just overwrite old versions with new versions

• Transfer is uni-directional. • Computer to controller

• You can’t “read” the box when it is running. • You can only determine if the problem is the program or the

component by changing the components.

• The box does not support “interrupts.”• Save program on thumb drive, not on studio

computers.• Download basic stamp program from Parallax web

site to your computer.

Programming Editor

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Program Structure

• Constants Table• Constants are substituted at compile time

• Variable declaration• Reserves portions of the Stamp’s limited memory

• Main program loop• Subroutines

• Often much of the work is done in subroutines

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Variables

• Variables are memory reservations on the BASIC Stamp

• Variables must be declared before they can be used

• Variable types are: • Word (16 bits): 0-65535• Byte (8 bits): 0-255• Nibble (4 bits): 0-7• Bit: 0-1

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Bytes, Nibbles, and Bits

1 byte = 2 nibbles = 8 bits:

B7 B6 B4 B3 B2 B1 B0B5

High Nibble Low Nibble

Most SignificantBit (MSB)

Least SignificantBit (LSB)

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Words and Bytes

1 word = 2 bytes = 4 nibbles = 16 bits:

High Byte Low Byte

Word

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Selected Commands

• Branching• If…Then• Goto• GoSub…Return

• Looping• For…Next

• Debugging• Debug

• Sounds (Music)• Freqout

• DC Motor Control• PWM

• Digital I/O• Input, Output• High, Low

• Serial I/O • Serout• Shiftin, Shiftout

• Time• Pause

• Power Management• End

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Best Way to Learn is to Do

• Read through the manual • Examine the sample programs and program

fragments• Studio assignment• Ask questions• Additional Information and Program

• www.parallaxinc.com (BASIC Stamp)

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Machining Studio

• Learn to Respect Machine Tools• Learn to Cut• Gain Experience• Generate Design Ideas• Build Confidence• Preserve Digits

Goals:

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Safety• No fooling around• Follow directions• Long pants (to your shoes)• Short sleeves or roll up sleeves• Socks• Closed toe shoes• Remove all jewelry

• watches, bracelets, rings, necklaces, dangling earrings

• Long hair must be tied back• No ties, scarves, dangling clothes• Always wear safety glasses• Violations will result in immediate removal from shop• Report all broken or non-working machines

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The Coupler

All tolerances ±0.010 unless otherwise specifiedAll dimensions in inches

0.500 0.650 ± 1/32 0.750

1/2-20 UNF6-32 UNCTHRU

0.125 φ0.750 DP

0.900 0.500

0.250

0.500+0.000-0.005

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The Bracket

0.250

0.325

0.325

0.250

0.250

0.400

0.400

1.5002.300 REF.

0.950 REF.

0.700

10-24 UNCTHRU2 PL TYP

0.950

All tolerances ±0.010 unless otherwise specif ied

1/8 RAD.

Bracket

All dimensions in inches

Electronics • Pneumatics • Machiningsinghose.marc.gatech.edu/courses/me2110...

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