Solar Car Controller Area Network

1
Solar Car Controller Area Network

• Auburns Solar Car Racing Team approached the
  Electrical Engineering department with a request
  for a networked system of microcontrollers to
  replace their current vehicles wiring harness to
  resolve these issues
• Excess weight associated with the current harness
• Reliability issues with the quantity of wires
• Difficulty in modifying the electronics
  configuration
• Driver safety issues resulting from component
  failures

Limitations

• Maximum power draw 12W (1A _at_12VDC)
• Minimize weight added to the vehicle
• Keep development and production costs low
• Replace all system I/O and communication with the
  CAN
• Make functionally ubiquitous to driver and chase
  vehicle
• Ensure safety of driver in case of network
  failures

Proposed Solution

• Functionally arrange components into 3 nodes
• Node 1 Motor Controller Module
• Node 2 Driver Display Module
• Node 3 Steering Column Module
• Connect the nodes using CAN technology
• Develop common hardware at each node
• Based around the Freescale HCS12 CPU
• Flexible, to serve all I/O needs at each node
• Use CodeWarrior to develop software to control
  all of the networks functions
• Serial communications
• Analog to Digital Conversion
• CAN interface
• LCD Driver Display
• Interrupt driven input
• General Purpose I/O

Key Benefits

• Increased communication among the three sections
  of the car
• Reduced weight
• Increased reliability
• Added level of safety
• Easily reconfigurable / expanded

• Developed a architecture capable of
  interconnecting all vehicle sub-systems
• Designed custom node hardware for the CAN
  physical layer (not built)
• Powerful HC9S12 microcontroller
• Two CAN interfaces
• Two RS-232 interfaces
• LCD controller
• Mixed signal input/output

• Coded control software to implement all I/O
  functions serial communications
• CAN messaging and priority assignment
• RS-232 control and pass-through capable
• ADC
• LCD display controller
• Interrupt driven user interface
• GPIO

Accomplished Goals
Team HelioLink Is Mike Cornelison Beau
Eckerman David Last Aaron Steiner Luke Stewart
Brian Whitehouse
2
Hardware Design
Hardware Block Diagram
Software Architecture
Node Hardware Schematic

• 64-pin Header
• Driver Display Interface
• 8-Channel ADC Connection
• 9 Interrupt Capable Inputs
• 8 Enhanced Capture Timers
• 22 GPIO

• 6-Pin ISP Connection
• Breaks out the ISP
• In-system debug module

Steering Controls Node
Motor Controller Node
Display Node

• Displays vehicle information to the driver such
  as speed and throttle position
• Features motor ignition, trip odometer, MPH/KPH
  toggle, and time-of-operation clock
• Receives data from chase vehicle via RS-232
  serial connection to wireless modem

• Allows driver to control throttle and braking
  using a potentiometer
• Provides cruise control with increment/decrement
  controls
• Sends throttle and cruise control information
  over CAN to motor controller and display

• Network Power Connector
• 2-Wire CAN network interface
• 12VDC Power in

• Exchanges data with motor controller via RS-232
  serial communication
• Sends serial data from motor controller over CAN
  to display and steering node
• Sends CAN data to motor controller over serial
  connection

• Freescale HC9S12DG128 Microcontroller
• 16-bit HCS12 CPU
• 128kB Flash EEPROM, 8kB RAM, 2kB EEPROM
• 2x SCI, 3x CAN 2.0 A B (1Mb/sec), I2C
• 2 8-channel, 10-bit ADCs
• PWM, Enhanced Capture Timer
• 29 GPIO Lines
• Low power operation modes

• ON Semiconductor MC34164 µC Supervisor
• Under-voltage power-on reset sensing

• Texas Instruments MAX202 RS-232 Transceiver
• Dual RS-232 level converters and line drivers

• Panasonic PCA82C250N CAN Transceiver
• High speed (1Mb/s) transceiver module
• Handles arbitration, packet formation