1. Safety Analysis
Ian Bacon
Zach Dicklin
Amy Ritter
Eric Yee

2. Definition of Criticality Levels
Safety Analysis
Definition of Criticality Levels
Loss of some functionality, reparable by user
Loss of some functionality, not reparable by user
Device unusable, reparable by user
Device unusable, not reparable by user
Device is a personal injury risk

3. Components for Analysis
Safety Analysis
Components for Analysis
Power Circuitry
Microcontroller
SD Memory Card
LCD Module

4. Safety Analysis
1) Power Circuitry

5. 1) Power Circuitry Safety Analysis # Failure Mode Possible Causes
Effects of Failure
Method of Detection
Criticality
Probability
Remarks A1
Circuit is not powered
LDO failure
Disconnected power component
Power supply failure, disconnect
-Device is unusable
-Observation status LEDs
-Test with DMM
3, 4 A2
Power is unregulated
PCB trace short
-Damage to critical components
-Device operates erratically
-Fire hazard
2,4,5

6. Safety Analysis
2) Microcontroller

7. 2) Microcontroller Safety Analysis # Failure Mode Possible Causes
Effects of Failure
Method of Detection
Criticality
Probability
Remarks B1
Peripheral components damaged
Shock
Unregulated power
Physical damage
-Comm.with peripheral lost or erradic
-Device is unusable
-Observation
2, 4
.58E-6 B2
Critical components damaged
-Device operated erradically
2,4

8. Safety Analysis
3) SD Memory Card

9. 3) SD Memory Card Safety Analysis # Failure Mode Possible Causes
Effects of Failure
Method of Detection
Criticality
Probability
Remarks C1
Read failure
Physical damage
Power surge
-Incorrect data read
-Device is unusable
-Software error detection
1,3
Easy, cheap, user fix C2
Write failure
Write lifetime exceeded
-Incorrect data writes
-Incorrect data reads
Depends on update frequency, likely between 2E-6 and 4E-6

10. Safety Analysis
4) LCD Module

11. 4) LCD Module Safety Analysis # Failure Mode Possible Causes
Effects of Failure
Method of Detection
Criticality
Probability
Remarks D1
Connection failure
Physical damage, disconnect
-Displays incorrect or garbled data
-Device is unusable
-Observation
1, 3
Easy fix D2
Power failure
-Disconnect
-Damaged power adapter
-Controller board power supply failure
-Blank display
3,4 D3
Backlight failure
Display lifespan exceeded
Power surge 4
25E-6
Failure likely in <5 years

12. 4) LCD Module (conti.) Safety Analysis # Failure Mode Possible Causes
Effects of Failure
Method of Detection
Criticality
Probability
Remarks D4
Controller board failure
Physical damage
Power surge
-Displays behaves erratically
-Display is blank
-Device is unusable
-Observation
-Software detection
2,4