Critical Design Review Dayrider

1
Critical Design Review - Dayrider

• Team Dayrider
• George Jenny, Amjad Sawaged,
• Tim Ikenouye, Kieran Tie

2
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

3
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

4
Block Diagram
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Motor - Traxxas Stinger 540

• 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

• 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

• 7.2 V _at_ 200 mA
• Thickness 0.6mm (24 mil)
• Total Size 253mm x 150mm
• Weight-25.9g

8
Microcontroller - TI MSP430F1611

• 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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I2C 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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I2C 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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I2C 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

• Controlled using PWM by additional MSP430F2003TN
  connected to I2C bus
• Steering mechanism 5 V supply servo motor, dead
  straight D 50, f 392 Hz _at_ 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

• Operating supply voltage 2.5 6 V
• Serial throughput of data via I2C
• 4 Analog input programmable with multiplexer
• Addressing via 3 hardware addressing pins
• 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

• Converts light intensity to output voltage
• Single supply operation 2.7-5.5V
• Connect to PCF8951 ADC
• Mount along perimeter of car

Output pulse falling edge
Output pulse delay rising edge
Output pulse fall time
Output pulse rise time
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TSL14S LVC schematic

• 4 LVCs connected directly into ADC
• We will have 2 of these modules for a total of 8
  LVCs

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Range Sensors - MaxSonar EZ1

• Analog 10mV/inch output
• Detection from 0 255 inches (20 ft.)
• Single 5V power supply
• Very low power draws only 2mA
• lt 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

• Assembled chassis with motor
• STAAB deep cycle battery (2)
• Traxxas Stinger 540 motor
• Solar Panels
• Linux router
• MAX233a level converters
• HAC-UM96 wireless transceivers

• MSP430F1611 microcontroller
• MSP430F2003 microcontroller
• LMD18200T motor controller
• PCF8591 ADCs
• TSL14S light to voltage converters
• MaxSonar EZ1 range sensors
• Sparkfun F1611 Dev board

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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

• 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
• 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
• Users 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?