1. Liz Lyons Mike Scherban Oscar Orihuela
Knightro Kart
Liz Lyons
Mike Scherban
Oscar Orihuela

2. What Is Knightro Kart?
An interactive, Android controlled vehicle race system consisting of two independent cars and controllers.
Vehicles are controlled by Android powered mobile devices or tablets
Consists of two independent vehicles, a track utilizing infrared, and two independent remote controls

3. System Block Diagram

4. Walkthrough

5. System Specifications
Bluetooth Communication Range
<30 m
Vehicle Speed
20 MPH max
Battery Life
>1 hr
Number of Users 2

6. Remote Control
Mobile device is used in landscape mode. It utilizes hardware level sensor data, and interprets it to tell the MSP430 how to direct the vehicle.

7. Why Android?
Essentially free – No new hardware costs, free SDK, familiar languages
Open source platform, easy to learn
Programming Language
Devices Readily Available?
Familiarity
Cost to Develop
Android
Java/XML
Yes
High
Free
iOS
Objective-C No
Medium
$99/year
Windows Phone
.NET framework/ Visual C++/XNA
Low

8. Target APIs 10 (Android 2.3.3 Gingerbread and higher), approximately 94.2% of Android market
Ice Cream Sandwich
Jelly Bean
Eclair
Honeycomb
Froyo
Gingerbread

9. Target APIs 10 (Android 2.3.3 Gingerbread and higher), approximately 94.2% of Android market
Ice Cream Sandwich
Jelly Bean
Eclair
Honeycomb
Froyo
Gingerbread

10. Wireless Communication Choices
Bluetooth
(Class 2)
Wi-Fi Direct
Wi-Fi (traditional)
Protocol
LMP, L2CAP, SDP
IEEE a/g/n
IEEE
Communication Distance
Radio dependent, ≈ 10 meters min
200 meters MAX
Speed
3 Mbps MAX
250 Mbps MAX
API Requirement
5 or higher
14 or higher
1 or higher
Power
2.5 mW
Varies
Varies, may be 40x Bluetooth
ISM Band
2.4 to GHz
2.4 GHz or 5 GHz
Difficulty
Low
High

11. Remote Control Requirements
Android device must:
Have Bluetooth capability
Contain accelerometer sensors
Have touch screen
Run Android Gingerbread or newer OS

12. User Interface
Home screen displays current lap, accelerometer values, and connected devices (if any)
Menu allows user to control the state of the remote control application
Connect A Device – connect to a vehicle
Start – send signal to BT module signifying ready to race
Reset Remote Control – reset application variables, sever connections
Exit – close the application and disconnect any active Bluetooth connections

13. User Interface
When user selects “Connect a Device” from the menu they are presented with a list of paired devices.
User can also search for unpaired, discoverable devices in the area
If connection is successful, the name of the connected device will be displayed on the main remote control screen.

14. User Interface
Home screen displays current lap, accelerometer values, and connected devices (if any)
Menu allows user to control the state of the remote control application
Connect A Device – connect to a vehicle
Start – send signal to BT module signifying ready to race
Reset Remote Control – reset application variables, sever connections
Exit – close the application and disconnect any active Bluetooth connections

15. Handling Accelerometers
Accelerometers are seen by the devices relative to an imagined coordinate system.
We use the Y (left/right) and Z (forward/back) axis values to control the cars

16. Bit Assignment Special Signals WAKEUP: 0xFF RESET: 0xBB 7 6 5 4 3 2 1
LEFT
RIGHT
SPEED 4
SPEED3
SPEED2
SPEED1
STOP
REVERSE
Special Signals
WAKEUP: 0xFF
RESET: 0xBB

17. Bit Assignment 0x84 0x44 0x04 0x88 0x48 0x08 0x90 0x50 0x10 0xA0 0x607 6 5 4 3 2 1
LEFT
RIGHT
SPEED 4
SPEED3
SPEED2
SPEED1
STOP
REVERSE
Action (Conditions)
Left
(YAccel < -2)
Right
(YAccel > 2)
Straight
(-2 < YAccel < 2)
Speed 1
(2 < ZAccel < 3.5)
0x84
0x44
0x04
Speed 2
(3.5 < ZAccel < 4.5)
0x88
0x48
0x08
Speed 3
(4.5 < ZAccel < 5.5)
0x90
0x50
0x10
Speed 4
(5.5 < ZAccel)
0xA0
0x60
0x20
Reverse
(ZAccel < -2)
0x81
0x41
0x01
Stopped
(-2 < ZAccel < 2)
0x82
0x42
0x02

18. Bluetooth Module Roving Networks RN-41 Minimal configuration
Baud rate
Auto slave, SPP
Built in antenna
Automatically pushes & pulls data via UART RX/TX pins
Runs own Bluetooth stack
Low power
3.3V
100m range

19. Microcontroller MSP430G2553 Atmega168 w/ Arduino 3.3V 5V 16KB flash
C, Assembly
16MHz
UART & PWM support
Bluetooth module runs at 3.3V as well
2.75”
2.75”

20. Microcontroller Same voltage as Bluetooth module
MSP430G2553
3.3V
16KB flash
C, Assembly
16MHz
UART & PWM support
Same voltage as Bluetooth module
No voltage level shifting
More feature rich IDE
Viewable registers
Real time setting/variable adjustment
Disassembly
SW breakpoints
G2553 variant
HW UART support
Bluetooth module runs at 3.3V as well

21. Microcontroller MSP430G2553 (28 pin TSSOP) Surface mount package
Function
# of Pins
UART 2
Start Line Signal 1
LEDs 5
Motors 4
Start Alert Signal

22. Programming and Debugging
Code Composer Studio free license
JTAG used to take advantage of IDE debugging features
Connect through TI USB FET device to 14 pin header

23. Motor Signals LEFT/RIGHT uses digital signals
FWD/REV take advantage of hardware PWM support
PWM used to add variable speed
Slow
Fast!

24. Microcontroller Comm.
MSP430Module: UART, 9600 baud rate, interrupts*
TrackVehicle: Port interrupt*, debounced
VehicleVehicle: Watch for port low to high change
*Interrupts: To catch events when they happen, opposed to hanging code and waiting to catch them
Interrupt code is ran regardless of which code is currently being executed

25. Low Power Mode Bluetooth module separate from MSP430
Allows BT pairing while MSP430 is asleep
MSP430 goes to sleep at power on and when not in race mode
Turns off clocks and CPU
Command from phone will wake the car for use
Only executes code in an interrupt
Explain how sleep works!

26. MSP430 Software Flowchart

27. Printed Circuit Board
Most components will be on a custom printed circuit board designed in Eagle

28. Printed Circuit Board Motors LEDs Track signal JTAG Power MSP430
BT Module and status LEDs
LEDs
Track signal
JTAG
Power
MSP430
Ready signals

29. Infrared Features Each race vehicle contains IR phototransistors
Biased by IR light
START line consists of an array of IR LEDs
Triggers phototransistors on vehicle, enables lap counter
Infrared also used for vehicle to vehicle communication

30. Race Vehicle 9.6V battery pack required Potential to travel 20 mph
2 D.C. motors
1st Motor controlling FWD and REV motion
2nd Motor controlling turning left and right
17 inches long
7 inches wide
8 inches tall

31. Motor Options Race car requires 2 motors
1st Motor controls – FWD & REV motion – D.C. motor
2nd Motor controls – Turning - D.C. or Servo
D.C. Motor
Servo Motor
Less Expensive
More Expensive
Requires Less Voltage to function
Requires Higher Voltage to function
Slower Reaction Time
Faster Reaction Time

32. H-Bridge MSP430 does not have sufficient voltage to run motors
H-bridge directs secondary power supply to motors
High/low signals received by H-bridge cause motors to spin in a certain direction
Ex: Clockwise / Counter-Clockwise / Stand Still

33. H-Bridge - Typical Typical H-Bridge configuration
Motor represented by inner
circle
Switches represent transistors
Motor is at a stand still

34. H-Bridge - Clockwise
The H-bridge is causing the D.C. motor to spin clockwise

35. H-Bridge – Counter Clockwise
The H-bridge is causing the D.C. motor to spin counter clockwise

36. SN754410 vs. L298N SN754410 L298N Max Motors 2 DC motors 2 DC motor
Max Continuous Current
1 Amp
2 Amp
VCC1 Supply Voltage Range
3.3V - 5.5V
4.5V – 7V
Max VCC2 Supply Voltage
36V
46V
Change LMD18200 for L298n!

37. SN754410 Cost efficient : $2.16 per chip Detailed documentation
Manufacturer: Texas Instruments
2Chips per car needed due to current restrictions
Each motor takes up to 1 Amp

38. SN Pin Out

39. Car Interior Schematic

40. Cooling SN754410 includes built in thermal shutdown
Generates enough heat to trigger shutdown
Aluminum heat sinks added to prevent shutdown
Fans to assist in cooling
Add picture of heat sinks & vector board HERE!!!!!

41. Power Supply Input Voltage Voltage Regulator SN754410 9V 5V Race Car
Does Not Require
MSP430
3.3V

42. Testing Had LEDs light up at certain events.
Connection successful
Byte received
Once we knew communication was successful, we tested with LEDs, SW breakpoints, and the register viewer to confirm correct bytes.
LEDs were used to confirm the correct motor output from PCB, using the tilt of the phone
Tested that the H-bridge received the correct logic and output the correct signals using a multimeter and motors
Finally tested that the car moved in accordance with the orientation of the phone

43. LED Notifications MSP430 asleep. Awaiting wake up
Ready to race, waiting for other car
Racing!

44. Issues Encountered
UUID assignment varies based on device receiving connection, had to look for the UUID corresponding to hardware (not android devices)
Surface mount devices smaller than anticipated
Overheating of the H-Bridge, heat sinks required
Syncing vehicles to start at the same time

45. Roadblocks
App occasionally takes more than one attempt to make a connection
Track LED spacing may be too large to trigger phototransistor 100% of the time
Cars slow down after continuous usage
Heat issue: heatsinks and fans multiplied the usage time
Needs a few seconds to cool down and run at normal speed
Unavoidable infrared light occasionally triggers phototransistors

46. What We Would Do Differently
For a more successful project we could have combined headers on the PCB to make the wiring easier and less cluttered
Use modulated infrared to prevent accidental triggers and allow outside usage
Use an H-bridge that supports more current and heat

47. Expenses Total: $ 410.00 Include Total To Date Costs Passive Comonents$
RC Vehicles $
PCBs $
Remote Control $
MSP430s $
Photo Transistors $
IR Lights $
H-Bridge Chip $
Bluetooth Modules $
JTAG Programmer $
Batteries $
Wood For Track
Fans $
Aluminum Heatsinks
Wiring and Cabling
Total: $
Include Total

48. Questions?