Ching-Han Tseng
Dominic Boiko
Frankie Ning
Harout Hedeshian
Joel Meisinger
1
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Design of a 3D printer for affordable
prototyping.
Prints each cross section of a 3D object layer
by layer
Three axis motion in a 3x3 feet chassis for
large scale modeling
Use of accurate stepping motors for high
precision printing
Network communication
2
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25mm/s linear write speed
0.5mm deposition resolution
5mm3/s (0.3 in3/s)
Capable of printing a 10cm3 object
Capable of printing functional prototypes
3
4
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Expected Dimension: 3 ft x 3ft x 3ft
3 stepping motors
5
6
5V
Wall
Power
CDH Controller
5V
12V
Motor
Controller
RS422 Bus
I/O
Encoder
Controller
Interrupt
Extrude
Header
Controller
7
Command and Data Handling
8
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Coordinate all events on printer
Communications interface for daughter
boards
Provide a physical human interface for high
level control
Platform independent and driverless
communications to host computer
9
DEBUG
EPS
5V
RS232
Power
Sequencing
5->3.3 Buck
5->2.5 Buck
ARM Cortex M3
(Stellaris LM3S6965)
Main CPU
I2C
USB>RS232
AVR MCU
(ATXMEGA128A1)
IO Hub
6-DIN
6-DIN
6-DIN
RS232
Ethernet
SPI
4Mb
RS422
Driver
RS422
Driver
RS422
Driver
Buzzer
LCD
Reset lines
Button
s
10

Choosing the Stellaris:
 On die Ethernet MAC and PHY
 Ethernet drivers already written by TI
 Have working code for MCU from prior projects

Choosing the XMEGA-A1
 Cheaper to use XMEGA than purchasing SPI-
UART converters.
 Allows Stellaris to be bypassed for fallback
11
I/O:
ATXMEGA128A1
•50MHz ARM Cortex M3
• 256KB Flash
• 64KB Single Cycle SRAM
• On die Ethernet MAC and PHY
• 3 x UART
• 1 x SPI
• 2 x I2C
• Why the 128 and not the 64: It’s in stock
• 32MHz
• 128KB Flash
• 8KB Single Cycle SRAM
• EBI for external buffer memory
• 4 x UART
• 4 x SPI
• 4 x I2C
12

Stellaris:
 FreeRTOS
 uIP
 Time permitting: lwIP
 Using a highly
modified Telnet server
implementation to
provide raw TCP
socket for
communication.
• XMEGA:
– Mostly interrupt
driven custom
firmware
– Simple functionality
acting as a “smart”
I/O controller.
– May use YAVRTOS
13
Single Price Estimate Quantity
Stellaris
15
1
30
XMEGA
10
1
10
RS422 Drivers
4
3
12
USB Transceiver
5
1
5
Inter-board connectors
1
3
3
Other connectors
7
1
7
Passives
5
1
5
Other Misc
10
1
10
Total
82
14

Primary risk: Ethernet non-functional
 Likelihood of success: 90% [Software working on
dev board, hardware design untested]
 Fall back to USB-UART

Secondary Risk: USB-UART non-functional
 Likelihood of success: 6.022E23% [Used controller
IC before and have several working designs using
said device]
 Fall back to UART on AVR
15
Electrical Power System
16
Power Supply




Provide each sub-system with appropriate power level
Maintain UL compliance
Isolated Power System
 Reduced Shock Hazard
 Continuity of power
 Noise Reduction
Over-current and short circuit protection
EMI Filter
Rectifier
Bridge
Feedback
Isolated
Wall
Outlet
120VAC
5V Forward
converter
(Isolated)
Transformer/
Reset
Winding
FPS
CDH
MDC
12V
Forward
converter
(Isolated)
PSC
SMC
Metallic Enclosure For Grounding
Relay(Enable)
Single Price Estimate Quantity
Full Wave Rectifier
2
1
2
Power Switch
4
1
4
Common Mode Choke
2
1
2
Diode(Rectifier, Vcc, Reset..)
2
4
8
Phototransistor
1
1
1
Bobbin/EE Core
15
1
15
Other Misc
18
1
18
Total
50
Risk
Primary risk: Shock/Explosion Hazard
•Example
•Over-current/short current protection, metallic enclosure grounding and isolation
are part of considerations to prevent this hazard
Secondary risk: Components go “Pooof-Hazard”
•Hand-made Transformers might not operate as ideal as the calculation
•Fall back to more detailed analysis, calculation, component upgrade, and proper
circuit protection.
Material Deposition Controller
21
Purpose of Subsystem
 Lay down the material of
choice (ABS plastic,
Epoxy) at a constant rate.
 Be able to stop and start
new point.
 Provide system feedback
CDH such as material
empty signal and motor
error signal.
22
MDC FBD
EPS
3.3V
DC/DC
converter
RS422
Driver
XMEGA MCU
CDH
5V
12V
Deposition
Motor
Driver
Deposition
Thermal
Driver
Print head
Thermal
Feedback
23
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Moderate melting point: 221°F, 105°C
ABS possesses outstanding impact strength and high
mechanical strength, which makes it so suitable for tough
consumer products.
Many colors.
Risk:
• ABS not working for dependable deposition
• Nozzle tip temperature not constant
Contingency plan:
1. Use other material type such as a epoxy plunger feed.
2. Use other tip sizes and materials.
24
Part Description
Part Number
Single Price
Estimate
Quantity
Total
Microcontroller
ATXMEGA64A3
5.47
1
5.47
Motor Driver
TB6560AHQ
4.73
1
4.73
RS422 Driver
ADM3071EARZ
4.00
1
4.00
RS232 Driver
TRS3221E
1.99
1
1.99
Optoisolator
LTV-847
1.00
9
9.00
DC-DC Regulator
FAN8303MX
1.35
1
1.35
External Oscillator
EFJ-N3385xxx
1.00
1
1.00
DB9 connector
1734348-1
1.00
1
1.00
Passives
-/-
5.00
5.00
Mechanical
-/-
30.00
30.00
Total
63.54
25
Position Sensor Controller
26

Objective
 Keep track of extruder head location
 Keep track of motor movements and provide
limit warnings

Requirements
 Supply CDH Controller with 3 axis position of the
extruder within 1/200th of a rotation
 Supply limit warnings and movement verification
to Stepper Motor Controller
27
RS232
EPS
ISP
PSC
6 GPIO
SMC
RS232
Driver
5V
3.3V
DC/DC
converter
XMEGA MCU
RS422
Driver
CDH
RS422
Encoder
X
Encoder
Y
Encoder Z
28
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Specs
 Optical
 Resolution (>200 count per motor cycle)
 Fits ACME threaded rod

Considerations





Index preferred
Quadrature preferred
Ease of Mounting/flexibility
Max Frequency Response
Low Cost
29
Part Supplier Cost
Resolution
(CPR x
Quadrecture)
Max Frequency
Response
Mounting
Signal
Integrity
Index
1250
DI
Anaheim
70.88
1250x4
100000
Fixed
Differential
Yes
500
DN
Anaheim
61.60
500x4
100000
Fixed
Differential
No
E8P
US
Digital
37.34
512x4
60000
Custom fit
Single
Ended
Yes
E5
US
Digital
51.50
540x4
60000
Custom fit
Single
Ended
Yes
500
SN
Anaheim
47.95
500x4
100000
Fixed
Single
Ended
No
30
Part Description
Part
Number
Single
Price
Quantity
Total
Microcontroller
ATXMega64A3
5.47
1
5.47
Encoder
E8P
37.34
4
149.36
RS422 Driver
ADM3071EARZ
4
4
16
RS232 Driver
TRS3221E
1.99
1
1.99
DC/DC Regulator
FAN8303MX
1.35
1
1.35
External Oscillator
EFJ-N3385xxx
1
1
1
DB9 Connector
1734348-1
1
1
1
Inter-Board
Connector
555051-1
2
1
2
5
1
5
Total
183.17
Passives
-/-
31
Stepper Motor Controller
32
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Controller for the three axis stage moving the
print head
Drives three 2-phase bipolar stepper motors,
one for each axis
Monitor motor current and temperature
Interface with main command and data
handling module
33
EPS
RS232
ISP
SMC
RS232
Driver
5V
3.3V
DC/DC
converter
XMEGA MCU
Temp
sensor
6 GPIO
PSC
RS422
Driver
Motor Driver
Motor Driver
Motor Driver
Linear
Actuator X
Linear
Actuator Y
Linear
Actuator Z
CDH
RS422
34
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Communication with CDH using RS-422
I/O to Toshiba Stepper Driver IC
(TB6560AHQ) that drive the motors
I/O from PSC for motor limits and motor
moving information
35
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Single 2-phase bipolar motor driver chip
 Controllable current for torque management
 Capable of half stepping and microstepping
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
Digital control inputs
Stepping speed determined by input clock
36
37
Part Description
Part Number
Single Price
Estimate
Quantity
Total
Microcontroller
ATXMEGA64A3
5.47
1
5.47
Motor Driver
TB6560AHQ
4.73
3
14.19
RS422 Driver
ADM3071EARZ
4.00
4
16
RS232 Driver
TRS3221E
1.99
1
1.99
Optoisolator
LTV-847
1.00
33
33.00
DC-DC Regulator
FAN8303MX
1.35
1
1.35
External Oscillator
EFJ-N3385xxx
1
1
1
DB9 connector
1734348-1
1
1
1
2
1
2
5
1
5
10
1
10
Total
91
Inter-Board Connector
Passives
Other
-/-
38

Current stepper motors might not produce
enough torque to move extrude head
 Very low risk

Current spikes of the motors damaging the
microcontroller
 Low risk with proper opotoisolation
39
40
Task
Primary
Secondary
CDH
Harout
Frankie/Joel
EPS
Ching
Dominic/Joel
MDC
Joel
Frankie /Harout
PSC
Frankie
Ching/Dominic
SMC
Dominic
Frankie/Harout
Mechanical
Harout / Dominic/ Joel
Ching/Frankie
User Interface
Harout
Dominic/Frankie
41

Gant chart
42
Category
Single Price Estimate
Quantity
Total
General
20
3
60
CDH
82
3
246
SMC
91
3
273
PSC
139
3(*)
251
EPS
50
3
250
Board Order
165
3
495
Total:
1575
Financial Support
UROP
800
Halleck Willard Inc.
Component
Donations (200)
Total :
1000
43
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