Eco Car Dashboard Display

1
Eco Car Dashboard Display

• ECE 345 Senior Design Project
• By
• Edward Wells and Darren Shea
• TA Ajay Patel

2
Layout of Presentation

• Introduction to EcoCar 2000 HEV
• Objective
• Original Design
• Software Overview
• Hardware Overview
• Costs and Labor
• Recommendations

3
Introduction To EcoCar 2000 HEV
4
Objectives

• Design display which is more suited to the EcoCar
  2000 HEV
• Design dashboard to work in conjunction with
  network and cruise control
• Retrieve information from the network
• Display the information on a LCD display panel

5
Original Design

• To design dashboard display suitable for Hybrid
  Electric Vehicle with backlit LCD display for
  digital information
• Pertinent information to be received from EcoCar
  network team via serial communications link
• Original analog speedometer and tachometer dials
  to be retained for better visualization of
  changes in these values

6
Main Software Flowchart
7
LCD Initialization Subroutine

• Problems
• No provided documentation
• Pins and connector
• LCD busy signal
• Enable line
• Different on-board chip

8
Displaying String Messages

• Purpose
• To become familiar with sending commands and data
  to the LCD display
• Initial Demonstration

9
Speedometer LCD Output

• Problems
• Scaling data
• Output input 0.5
• Resolution
• Trying to scale analog input should have been
  binary conversion

10
Tachometer LCD Output

• Problems
• Scaling data
• Output (input 3- 65)/10
• Same conclusion as speedometer output
• Warning light never functioned properly, used
  non-scaled binary value

11
Analog Data Output

• PROBLEMS
• Tried to use same control lines with inverter for
  both Digital to Analog Converters
• In theory, should have worked, but data not
  latched properly
• Simpler solution, use two more control lines

12
Delay Function

• 0.587ms time delay
• LCD busy signal
• 0.35 ms
• Used delay function instead of reading LCD busy
  signal
• Long delay(25ms)
• for refreshing of screen

13
Analog System Overview
14
Digital to Analog Converter

• Based on DAC 0830
• Controlled by micro controller
• MC1404 used for accurate reference voltage

15
DAC calculations
Iout (VREF/15k) x (Digital input)/255     VREF
(Iout x 15k)/( 15k x 255/256)   Iout
Vout/15k   Vout 4V therefore Iout 2.667
x 10-4 A   Which gives   VREF 4.016V   So
for a single step,   Iout 1.0459x10-6A
Vout 15.6882mV
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Timing Diagram

• Microprocessor writes to one port
• Chips switched on and off corresponding to data
  on port
• Data latched when WR goes high

17
Voltage to Frequency Converter

• Provides pulse train for odometer driver
• LF411 used as integrator for higher accuracy
• Low tolerance, low thermal coefficient
  components, required for high accuracy

18
VFC Correction Circuit

• Non-inverting amplifier
• High gain to clean pulse train
• Adjustable off set to make pulse train positive

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VFC calculations
Fout (-Vin/2.09) x (Rs/Rin) x (1/RtCt)   Max
input voltage -4.1V Max required frequency
90Hz   Rs 12.1k Rin 100k Ct 0.01uF   90
(4/2.09) x (12.1/100) x (1/(Rt x
0.01x10-6)   Rt 257.3k?   The closest value
in the E12 series is 220k?
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Odometer Driver

• CS8441 odometer driver
• Frequency input
• Calculates correct sequence for stepper motor

21
Gauge Controller

• CS8190 air core gauge driver
• Voltage input used instead of frequency
• LF411 drives voltage into chip bypassing
  frequency conversion circuits

22
Costs Labor
Labor Typical EE entry salary 50,000/year 1
year / 240 days 1 day / 8 hours
26/hour 26/hour 2.5 150 hours 9,750per
person Total Labor
19500 Parts LCD display 38 68HC11
Microcontroller 30 Resistors,
Capacitors 5 DAC 0830 7.08 x2 LM331
8.16 LF411 1.27 x 3 LM741 0.46 x4 CS8190
2.80 x 2 CS8441 2.00
Total Parts 108.57
Total Costs 19,608.57
23
Recommendations

• Wanted to interface with network and cruise
  control teams, display in EcoCar
• Backlit LCD display
• Add more functionality
• e.g. More warning lights, more complex LCD
  display