Critical Design Review “Dayrider”
Team Dayrider
George Jenny, Amjad Sawaged,
Tim Ikenouye, Kieran Tie
Objectives
 Minimum: A solar-powered, router-controlled
RC vehicle
 Target: A self-controlled software-sensor
interface with regenerative techniques for energy
recapture measurements
 Optimal: A vehicle that combines efficient
design, functional power management, and a
dynamic user interface in an aesthetically pleasing
package
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Status
 Components selected and shipping
 Preliminary wire-wrapping of modular
pieces (ADCs)
 Control software of the MSP430 I.P.
 Schematics: main board, subsystems
sketched out and transferring to Altium
 Router hardware/software modifications
completed
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Block Diagram
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Motor - Traxxas “Stinger 540”
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20-turn DC brushed motor
~1.5A at 3V no load
~33mA at 500 mV reverse
Already standard on the current chassis
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Battery – STAAB
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6V output
3.4 Amp-hour capacity
7-7.5 rated charging V
~0.692 kg
134mm/34mm/60mm
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Solar Panels
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7.2 V @ 200 mA
Thickness 0.6mm (24 mil)
Total Size 253mm x 150mm
Weight-25.9g
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Microcontroller - TI MSP430F1611
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16 bit RISC CPU
8 MHz operational frequency
48 KB Flash, 10 KB Ram
48 GPIO pins
Analog Comparator, DMA
Hardware Interface:
 2 UART or SPI for hardware Interface: (USART 0,
USART1)
 I2C mode for peripheral interface
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Microcontroller - TI MSP430F1611
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Modular Peripherals
 Hardware addressed on each peripheral board
 Plug and Play onto main board
 Modularized design allows for easier assembly and
debugging
 I2C Bus: supports 7 and 10 bit addressing modes (p308
user guide)
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2
IC
Bus
 Basic implementation of I2C Bus
 Must be implemented in USART0
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USART0 Control Register
RXDMAEN - Transmit data from I2C via
DMA upon receiving data
SYNC – (1) for [SPI or I2C] mode, (0) for
UART mode
I2C – (1)selects I2C mode when SYNC = 1
I2CEN – enables(0) or disables(1)
operation of I2C mode
MST – selects master (1) or slave (0) mode
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2
IC
Timing Diagrams
One clock pulse is generated by the master device for each data bit
transferred. The I2C module operates with byte data. Data is transferred most
significant bit first as shown in Figure 15.3
STOP
Condition:
SDA Low
to High
while SCL
is High
START
Condition:
SDA High
to Low
while SCL
is High
Change of Data only
allowed while SCL is
Low, otherwise START
and STOP conditions are
generated
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2
I C Addressing
Scheme
Start
Condition
Stop
Condition
Acknowledge bit sent by
receiver after each byte
Direction of data flow on SDA can be changed by master by issuing a repeated
start condition: RESTART is issued, slave address issued with new value for
R/W bit
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Motor Controller - LMD18200T
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Controlled using PWM by additional MSP430F2003TN connected to I 2C bus
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Steering mechanism: 5 V supply servo motor, dead straight D = 50%, f = 392 Hz @ 1 V,
modulating D from 40% – 60% steers left to right.
Functional diagram
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Motor Controller Schematic
3 inputs to motor controller supplied by smaller MSP430F2003
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Analog to Digital Converter - PCF8591
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Operating supply voltage 2.5 – 6 V
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Serial throughput of data via I2C
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4 Analog input programmable with multiplexer
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Addressing via 3 hardware addressing pins
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Sampling rate given by I2C bus speed
Programmable
hardware bits
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ADC schematic
4 input ports
I2C interface
3 programmable
hardware bits
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Light-to-Voltage Converters - TSL14S
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Converts light intensity to output voltage
Single supply operation 2.7-5.5V
Connect to PCF8951 ADC
Mount along perimeter of car
Output pulse
delay rising
edge
Output pulse
rise time
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Output pulse
falling edge
Output pulse fall
time
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TSL14S LVC schematic
•4 LVC’s
connected
directly into
ADC
•We will have 2
of these
modules for a
total of 8
LVC’s
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Range Sensors - MaxSonar EZ1
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Analog 10mV/inch output
Detection from 0 – 255 inches (~20 ft.)
Single 5V power supply
Very low power; draws only 2mA
< ½ the size of other sensors in its class
Connect to PCF8951 ADC
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Range Sensor Schematic
•All 3 sensors
multiplexed in 1 ADC
•Same ADC used
throughout all
peripheral modules
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Parts List
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MSP430F1611 microcontroller
MSP430F2003 microcontroller
LMD18200T motor controller
PCF8591 ADC’s
TSL14S light to voltage
converters
 MaxSonar EZ1 range sensors
 Sparkfun F1611 Dev board
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Assembled chassis with motor
STAAB deep cycle battery (2)
Traxxas Stinger 540 motor
Solar Panels
Linux router
MAX233a level converters
HAC-UM96 wireless
transceivers
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Serial Communication - MAX233e
 Converts TTL/CMOS levels coming from
router/microcontroller to RS232 levels for
computer/HAC-UM96
 2 needed - one for router, and one for
microcontroller/UART
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Serial Communication - HAC-UM96
 96kbps wireless
transceivers
 Transmission power
10mW
 433MHz frequency
 Range 300-500m
 Takes TTL or RS232
inputs - will use RS232
for ease of debugging
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Software - MSP430
 Written in C / Assembly
 Developed using IAR
Embedded Workbench
 Tested on prototyping board
from Olimex
 Final version transferred to
main circuit
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
 No software yet, but…
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Software - MSP430
 Use Cases - Outline
software algorithms for the
operation of the vehicle
 UC1 - Avoid Obstacle
 UC2 - Drive to Sunlight
 UC3 - Drive Vehicle
 Test cases for all possible
paths of use cases
 Domain model under
construction…
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Software - Linksys WRT54G
 Linux - OpenWRT
 lighttpd - web
server
 Ajax - live updating
of site
 PHP - system
commands
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
 Serial data
processor
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Web Interface - Concept
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Web Interface - Demo
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Division of Labor
 Software
Kieran & Amjad
 User’s Interface (webpage)
 Autonomous Control
 Peripherals
 Hardware
Tim & George
 Wire-wrap board
 Peripherals
 Regenerative Braking
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Milestone 1: November 2
 Preliminary MSP430 code
 Serial communication between vehicle and
router
 Moving Vehicle
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Milestone 2: November 30
 Completely Solar/Battery Powered
 User control of Vehicle
 Range Sensors
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Expo: December 14
 Energy Regeneration
 Peak Power Tracking
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Schedule
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Questions?
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