Aarthi Balachander Daniel Jiang Drew Schuster Ryne Rayburn

Aarthi Balachander Daniel Jiang Drew Schuster Ryne Rayburn We are Wireless Audio (Wa. WA) Safety and Reliability Analysis

Components Most Likely to Fail �Microcontroller – LPC 2377 Utilizing I 2 S, oscillator, UART, SPI 144 pins – most complex component �Voice Recognition Module HM 2007 has own PCB with many components Microphone failure/inaccuracy = Module failure �Amplifier – LM 4950 �Regulators – LM 317 and LM 7805 Inputs are 12 V and 5 V, outputs are 5 V and 3. 3 V

Definition of Criticality Levels �High – safety risk �Medium – no safety risk, but device largely dysfunctional �Low – no safety risk, minor feature not operational

Microcontroller Failures Failure No. Failure Mode Possible Causes Failure Effects Method of Criticality Detection Remarks M 1 Does not receive power Regulator circuit not producing 3. 3 V; Power supply; Shorted bypass caps Entire design not functional Observable Medium Device will not function, but no safety risk M 2 SPI port Software; PCB problem; u. C component failure Inability to adjust volume Observable High Could cause damage to speakers/hearing M 3 UART Software; PCB problem; u. C component failure LCD/Wireless module failures Observable Medium Device will essentially not function, no safety risk M 4 Oscillator problem Software; PCB problem; u. C component failure Inability to clock the audio codec Observable Medium Will not be able to convert audio between A and D M 5 GPIO Software; PCB problem; u. C component failure Cannot receive state of push buttons/speech Observable Low No user interface

Speech Recognition Failures Failure No. Failure Mode Possible Causes Failure Effects Method of Criticality Detection Remarks S 1 Does not receive power (3. 3 V) Inter-PCB connection problem Module will not operate Observable Low Part of user interface crippled S 2 Recognition failure Microphone failure; Training problem Speech commands inoperable Observable Low Part of user interface crippled S 3 Transmission failure Inter-PCB connection problem; PCB problem; u. C GPIO fault Cannot send data over to microcontroller Observable Low Part of user interface crippled

Amplifier Failures Failure No. Failure Mode Possible Causes Failure Effects Method of Criticality Detection Remarks A 1 Inadvertent Shutdown Active low shutdown pin does not receive enough voltage No audio output on remote station Observable Medium Device not functional, but no safety problems A 2 Over amplification Shorted resisters Audio too loud; noise Observable High Damaging to hearing; heat from amplifier

Power Failures Failure No. Failure Mode Possible Causes Failure Effects Method of Criticality Detection Remarks P 1 Power rails have no voltage Voltage regulator circuit failure No power to circuit Observable Medium Device not functional, but no safety problems P 2 Power rails voltage too high Voltage regulator circuit; Power supply failure (disconnection) Components may be damaged Observable High Voltage too high could cause components to heat up: danger to user

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