ECE 477 Digital Systems Senior Design Project Spring 2005

ECE 477 Digital Systems Senior Design Project Spring 2005 The FEMCA is below. ECE 477 Digital Systems Senior Design Project Spring 2005

FMECA Worksheet – Group 5____ Motor Control – Block A

Failure Failure Mode Possible Causes Failure Effects Method of Criticality Remarks No. Detection A1 BJT stuck Open Damage or misuse of Motor coil on that Operation Low Device would be any LM3046 in block BJT would inoperable but no A constantly be damage would be powered, thus caused. inoperable A2 BJT stuck Closed Damage or misuse of Motor coil on that Operation Low Device might be any LM3046 in block BJT would be inoperable but no A constantly off. damage would be caused.

A3 Steering Diodes Damage to any diode Current could Operation Low Just a guess as didn’t Fail in block A backtrack into analyze diodes above LM3046 and cause damage

FMECA Worksheet – Group 5____ Microprocessor – Block B

Failure Failure Mode Possible Causes Failure Effects Method of Criticality Remarks No. Detection B1 Output Stuck Damage or misuse of Any device Operation Low Damage is unlikely as High PIC18LF4431 connected to PIC signals from PIC act to would not send data, interrupts, or function correctly activate gates.

B2 Output Stuck Damage or misuse of Any device Operation Low Damage is unlikely as Low PIC18LF4431 connected to PIC signals from PIC act to would not send data, interrupts, or function correctly activate gates.

B3 Reset Switch Damage to switch PIC would have Operation Low Just a guess as didn’t Failure no means of reset analyze switch above besides power cycle

B4 Capacitor Failure Damage to any PIC would not Operation Low Most likely nothing capacitor in block B have proper would happen but PIC bypass caps could start odd behavior.

FMECA Worksheet – Group 5____ Power – Block C

Failure Failure Mode Possible Causes Failure Effects Method of Criticality Remarks No. Detection C1 Wall Wart Failure Damage or misuse of Incorrect power Operation Low Too much and parts Wall Wart would get from could fry, too low and wall to board device might not function

C2 Battery Failure Damage or misuse of No power backup Operation Low Damage unlikely batteries system

C3 Steering Diodes Damage to any diode Current could Operation Low Just a guess as didn’t Fail in block C backtrack into analyze diodes above battery

C4 MIC29150 Fails Damage to diodes in Incorrect power Operation High This could cause block C or to would get to damage to the MIC29150 microprocessor or microprocessor, and is other components only real injury threat as fire is possible. C5 LED Failure Damage to any part Would not have Operation Low Just a guess as didn’t in block C way to tell if analyze LED above power is present in circuit

FMECA Worksheet – Group 5____ Audio – Block D

Failure Failure Mode Possible Causes Failure Effects Method of Criticality Remarks No. Detection D1 LM386 Failure Damage or misuse of Sound system Operation Low Sound could be LM386 would not inoperable but no function correctly damage would be caused.

D2 Capacitor Failure Damage or misuse of Sound system Operation Low Sound could be any Capacitor in would not inoperable but no block D function correctly damage would be caused.

FMECA Worksheet – Group 5____ RS232 – Block E

Failure Failure Mode Possible Causes Failure Effects Method of Criticality Remarks No. Detection E1 MAX3235 Damage or misuse of Communication Operation Low Communication could Failure MAX3235 between PC and be inoperable, damage PIC would not would be unlikely. function correctly

FMECA Worksheet – Group 5____ Switch – Block F

Failure Failure Mode Possible Causes Failure Effects Method of Criticality Remarks No. Detection F1 MAX6818 Damage or misuse of User interface Operation Low Just a guess as didn’t Failure MAX6818 would not analyze MAX6818 (de- function correctly bouncer chip) above, damage is unlikely

F2 Switches Fail Damage to any User interface Operation Low Just a guess as didn’t switch/button in would not analyze switches above, block F function correctly damage is unlikely

It is not necessary to calculate the probability of each failure mode. These numbers would usually be taken from the reliability analysis, but since you are not performing a complete analysis, they do not need to be included in your FMECA worksheet.