Technical Communications Practicum: Failure Modes, Effects and Criticality

Analysis

SmartShopperJeff Richards, John Sweeney, Stevi Wood and Tera Wong

Primary Subsystems• Voltage Switching Regulator

• RFID Reader

• USB Module

• Microcontroller

• Digital Compass

• LCD

Voltage Switching Regulator and Circuitry

A

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

A1 Output voltage is over spec

Failure of C6, R3, D1, D2, D3, D4, R4, R5, R8, R9, L1, L2, C12, C11, C10, C9, R6, R7,

C7, C8

Overheating or improper

functioning Observation High

Potential injury to the customer overheating

leads to fire. Could also cause damage to other components of design.

A2 Output voltage is under spec

Failure of C6, R3, D1, D2, D3, D4, R4, R5, R8, R9, L1, L2, C12, C11, C10, C9, R6, R7,

C7, C8

Improper functioning Observation Low

A3 No output voltage Failure of BT1, C6 System has no

power Observation Low

A4 Short of the battery

Failure of bypass capacitor (C6)

Overheating or improper

functioning Observation High

Potential injury to the customer overheating

leads to fire. Could also cause damage to other components of design.

RFID Reader Connectors and Supporting Circuitry

B

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

B1 No input

Faulty wire connection to

header; Faulty RFID module; Failure of

U6

Unable to locate specific items on

shopping list, which was input by

customer

Observation Low

The RFID tags are not located throughout the store. Microcontroller

receives no data.

B2 Incorrect output

Faulty wire connection to

header; Faulty RFID module; Failure of

U6, C20, C17, C16, C18, C19

Items on shopping list not found or

wrong item indicated as found

Observation LowThe wrong RFID could

be passed to the microcontroller

USB Controller and Connector

C

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

C1No input from USB memory

stick

Faulty USB connector; Failure of Y1, R1, R2, C3, C4, C5

Shopping list is not loaded Observation Low

C2 Incorrect input voltage level

Failure of C2, C1, C5, U4

Shopping list is not loaded Observation Low

Microcontroller

D

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

D1 Incorrect outputFailure of internal

microcontroller circuitry, software

Jumbled LCD display Observation Low

D2 Constant output value

Failure of Y6, C14, C15

Unchanging LCD display Observation Low

D3 No output to LCD display Failure of I/O pins Nothing on LCD Observation Low

D4No power or

incorrect input voltage levels

Failure of U4, bypass capacitor

Nothing on LCD Observation Low

D5 Reset signal flickering

Failure of R12, CW3,

softwareIntermittent display

on LCD Observation Low

Digital Compass Connector

E

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

E1 No output Faulty wire connection to header

Instructions are not updated

automatically Observation Low

The user will have to push a button for the

next instruction.

E2 Incorrect output Out of calibration

Instructions are not updated at

appropriate time or not at all

Observation Low

The user will have to push a button for the next instruction. And

product might possibly give incorrect instructions.

LCD Connectors and Supporting Circuitry

F

Failure No.

Failure Mode Possible Causes Failure Effects Method of Detection

Criticality Remarks

F1 No characters on LCD

Faulty I/O connection; Faulty LCD; Failure of U3, U6, , C20, C17, C16,

C18, C19

Impossible to see/read the

directions being given.

Observation Low

F2Invalid

characters on LCD

Faulty I/O connection; Faulty LCD; Failure of U3, U6, C17, C16, C18, C19

Impossible to comprehend the directions being

given.

Observation Low