Team 9 - Scribacious RabbleSafety and Reliability Analysis

Mitchell Erdbruegger (presenting)Paul Rosswurm

William HessBen Kobin

Project Description

Adaptation of the board game SCRABBLE® Maintains the traditional physical tile interface... augmented by ..

Sensing tile location and value Automatically calculating and displaying scores Maintaining player profiles Validating words in the event of a 'challenge' Exposing game stats over an external interface

PSSCs

An ability to sense the presence and identity of a tile placed on the board.

An ability to record game specific metrics for a set of player profiles.

An ability to use a standard dictionary to allow a player to challenge the validity of the last word played.

An ability to display game relevant information to each player and allow one user to input game settings.

An ability to communicate game statistics over an external interface.

Block Diagram

Chosen Parts

• Micro-Controller (PIC24EP256GU810) λP = (C1* πT + C2 * πE) * πQ * πL

λP = ( 0.28 * 1.5 + 0.068 * 2.0) * 10 * 1.0

λP = 5.56

MTTF: 20.5 Years

• Low Drop-Out Linear Regulator (LM1117) λp = λb*πT*πS*πC*πQ*πE

λp = .0020 * 5.1 * 1.0 * 1.0 * 6.0 * 8.0

λP = 0.4896

MTTF: 233 Years

Chosen Parts• 8-Bit Shift Register (74HC164D)

λP = (C1* πT + C2 * πE) * πQ * πL

λP = ( 0.005 * 1.5 + 0.0062 * 2.0) * 10 * 1.0

λP = 0.199

MTTF: 573.25 Years

• Opto-Isolator (LTV-826S) λp = λb*πT*πQ*πE

λp = 0.017 * 6.6 * 2.0 * 8.0

λP = 1.7952

MTTF: 63.5 Years

• Others Considered• LCD Driver (Sitronix ST7565P)

• Capacitive Grid

Criticality Levels

• Low

• < 10-5 Failures

• No Harm to Users

• Possibly render product unusable

FMECAPower Supply and LCD Circuits

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

 

PS1

 

VOut = 0

 Failure of the LM1117, Shorted Decoup Caps

 No Power to the rest of the system, Entire product useless

 Observation (Use of voltmeter to check input/output voltage)

 

Low

 

 

PS2

 

VOut > 3.3V

 Failure of the LM1117

 Could potentially cause irreparable damage to ICs

 Observation (Voltmeter on output)

 

Low

 Possibly fixed with zener diode to protect rest of circuit

 

L1

 Output LCD

Contr Always 0

 LM1117 Failure (PS1), Shorted Decoup Cap, Burned out contr. (Possibly PS2)

 No backlight on the LCD

Observation (Oscilloscope readout) Low

 

 

L2

 No power going

to LCDs

 LM1117 Failure (PS1), Shorted Decoup Cap

 Nothing can be ouput to LCDsProduct rendered essentially useless

Observation (Volt meter)

Low

 

Power Supply

FMECAMicro-Controller

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

M1USB D- and D+

always 0 or 1

Software bug, broken usb module (possibly cause by PS2), Connected USB device pulling low or high

Failure to communicate player statistics to PC via USB

Observation (Oscilloscope)

Low

M2Micro Pins at constant signal (0 or 1)

Burned out pins (too much current or voltage placed on pin), software

Peripherals malfunctioning

Observation(Volt meter/ oscilloscope) Low

M3MCLR always 0

Broken reset button, burned out pin, shorted decoup caps

Micro useless due to always sin reset

Observation (voltmeter)

Low

M4MCLR always 1

Broken reset button, burned out pin

Mirco cannot recover without turning off power (for debug purposes only)

Observation(voltmeter)

Low

Micro and Reset

FMECASD Card, Push Buttons, Column Inputs, Row Select

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

SD1No Read/Write Functionality to

SD

Damaged SD Card, Shorted Decoup Caps, LM1117 Failure, SPI malfunction

Cannot read or store player data

Observation (Plug into PC and check if data written, Attempt to read player data via USB)

Low

PB1PB Inputs always

low

Failed pull up resistor, Shorted decoup caps, LM1117 Failure

No user input can be obtained, game rendered useless

Observation (Volt meter)

Low

C1Input from

column alsways 0 or 1

Failed opto-isolator, Failed buffer, Burned out micro pin

Cannot sense tiles properly

Observation (Oscilloscope.Voltmeter) Low

RS1Output to row always 0 or 1

Burned out pin on micro, burned out shift register, shorted decoup caps, LM1117 failure, Software, burned out buffer

Inability to sense tiles on board

Observation( Voltmeter/ Oscilloscope) Low

Column Inputs

Row Selection

QUESTIONS/COMMENTS?