An In-Depth Look At DARSI

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An In-Depth Look At DARSI
Presentation Outline
Data Acquisition Real-Time System Integration

• Project Overview
• Sensor Systems
• Communication
• Main Board Storage
• Project Administration Management

Matt Hulse Marc Kessler Chris Lites Preston
Schipper Andy Lin
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DARSI Project Overview
Our data acquisition system

• Sensors
• Sensor pre-processing units
• Sensor network communication
• Main processing
• Storage

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Where Are We Now?

• Sensors
• Testing apparatus
• Wheel speed tested and implemented with
  pre-processor
• Linear position sensor circuit prototype
• Microcontroller (Preprocessor)
• Development environment for processor working
• Preprocessor system prototype
• Coding complete except CAN communication
• Main processor Written code developed
  schematics

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Sensors
Wheel Speed -Hall effect -5V supply
Shock Position
LVDT Linear Variable Differential Transducer
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Sensor Microcontroller PIC18F258
Preprocessor Details

• 16 MHz
• C Programmable
• Hardware CAN
• A/D Converter

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Microcontroller Details
23 GP I/O External Clock 5 10-bit A/D
Converter 1536 RAM (256 used) Hardware CAN ICSP
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PIC18F258
BlockDiagram
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Code
void configure_a_d_c(void) void
configure_sample_timer(void) void
configure_interrupts(void) void
int_handler(void) void get_dev_id(void) void
resistive_samples(void) void frequency_samples(vo
id) void can_send(int my_data) void
set_constants(void) void no_calib_data(void) voi
d EEPROM_Write(int location, int value) void
main (void) get_dev_id() SetCBEmpty(raw_data
_buffer) //SetCBEmpty(send_data_buffer) //DE
FAULT VERSION EEPROM_Write(255,2) set_constant
s() configure_a_d_c() configure_sample_timer()
configure_interrupts() PORTAbits.RA1
1 PORTC dev_id if(sample_type
0) while (reset_now 0) resistive_sa
mples() else if(sample_type
1) while (reset_now 0) frequency_sa
mples()
include ltp18f458.hgt //for chip ports include
ltadc.hgt //for A/D conf include lttimers.hgt //for
timer conf include "CB256.h" struct CB
raw_data_buffer //struct CB send_data_buffer st
ruct pulse_data int csample int
psample int pulses int trigger_level int
cur_pulse int samples frequency_data char
dev_id char reset_now 0 char
raw_data_overflow 0 char send_data_overflow
0 char counter 0 int sample_time int
timerval int speed char wheel_dia char
num_teeth char sample_type 0 /Valid Sample
types 0 Voltage 0-5 corresponding to
resistance 1 Periodic corresponding to
frequency /
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Inter-Sensor Communication
Controller Area Network
In a CAN system, all messages sent out on the bus
are detected by all nodes on the bus.

• Error detection
• Bit stuffing
• Cyclic redundancy check
• Self checking
• Probability for undetected corrupt message lt
  message rate 4.7 10-11

• CAN 2.0A
• 11 bit identifier field

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Data Frames
Data Frames Data, Remote, Error, Overload
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Main Control Board
PIC18F458 Voltage Regulator Flash
Controller Master Controller for CAN
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Details
Same Family and Data Sheet Two more Ports (8 bit
registers) 8 bit Parallel 2 comparators (not
used) Total 34 I/O compared to 23 I/O
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Memory
Smart Media 22 Pads 8 bit parallel I/O FAT16
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Parts List

• PIC18F258
• PIC18F458
• Software Development Tools
• Honeywell hall effect sensor
• Linear Variable Differential Transducer
• Assorted inverters, voltage regulators, DIP
  switches, clocks

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Labor Responsibilities

• Andy
• PCB design
• Christ Matt
• CAN bus

• Marc
• In circuit serial programming (ICSP)
• Software development
• Preston
• Memory

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Milestone Goals

• Milestone 1 Goals
• Sensor Unit
• Main control schematics
• CAN working on preprocessor in loop-back mode

• Milestone 2 Goals
• Everything constructed
• Final debugging testing

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Schedule CDR ? Expo
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Questions Answers

• Thank you