Bifrst Visualizing and Checking Behavior of Embedded Systems across - PowerPoint PPT Presentation

Bifröst Visualizing and Checking Behavior of Embedded Systems across Hardware and Software Will McGrath – wmcgrath@stanford.edu Jeremy Warner – jeremy.warner@berkeley.edu

e M bedded G ateway C loud [MGC] embedded gateway cloud 2

e M bedded G ateway C loud [MGC] embedded gateway cloud 3

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Program logic bug? 5

Program logic bug? Protocol error? 6

Program logic bug? Protocol error? Wiring issue? 7

Program logic bug? Protocol error? Peripheral not configured? Wiring issue? 8

Sensor data out of range? Program logic bug? Protocol error? Peripheral not configured? Wiring issue? 9

Sensor data out of range? Defective part? Program logic bug? Protocol error? Peripheral not configured? Wiring issue? 10

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Toast Board Measures analog voltages at all breadboard rows Compares measured results to intended circuit to identify errors No embedded software support 12

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Existing Embedded Debugging Techniques • Multimeter • Point to point • Obscures rapid changes • Oscilloscope/Logic Analyzer • Fast, but expensive • Nontrivial configuration • Print Debugging • Easy, but weak time information • GDB • Powerful, but not always available • Complex configuration 16

In contrast with prior work which has focused on providing tools only for debugging software or circuits, we directly address the interconnected nature of embedded systems projects. 17

We believe that giving developers insight into how hardware and software interact in a richly-linked environment will enable more efficient debugging of embedded systems. 18

Hardware Software Sensors Actuators 19

Bifröst 20

Bifröst: IDE Overview Trace Digital Signals Analog Signals Variable Values User Program Time-linked console Code line at current time 21

Instrumentation Capture Analysis 22

Instrumentation Capture Analysis Hardware Instrumentation: Digital signals Analog signals Software Instrumentation: Line numbers Variable values 23

Instrumentation Capture Analysis Hardware Instrumentation: Digital signals Record with Analog signals Logic Analyzer Software Instrumentation: Line numbers Variable values 24

Instrumentation Capture Analysis Hardware Linked Visualization Instrumentation: Digital signals Signals Record with Analog signals Logic Analyzer Code Console Software Instrumentation: Automatic & User Line numbers Authored Checks Variable values 25

Bifröst: usage example 26

Bifröst: configuration 27

Bifröst: blinking LED 28

Bifröst: recording data 29

Bifröst: variable tracing 30

Bifröst: trace ⇔ code linkage 31

Bifröst: code-based navigation 32

Bifröst: console-based navigation 33

Data Capture 34

Capture: example Backend 35

Capture: setup Backend Program Code 36

Capture: setup Backend Configuration Program Instrumented Code Code 37

Capture: execution Backend Debugging information: code lines + function info 38

Capture: execution Backend Trace (w/ debug info) + decoded protocols Debugging information: code lines + function info 39

Capture: execution Backend Trace (w/ debug info) + decoded protocols Trace + Debugging Debug + information: Protocol code lines + function info 40

Capture: inspection incrementally step, record, and visualize 41

Code Instrumentation 42

Code Instrumentation 43

Core Library Instrumentation 44

Checks automatically inferred user-parameterized 45

Checks: automatically inferred “ Writes should generate activity on a pin” “Communication protocols adherence” 46

Checks: user-parameterized "when D1 rises expect line 11 in 100 ms" 47

Checks: user-parameterized "when D1 rises expect line 11 in 100 ms" pin 48

Checks: user-parameterized "when D1 rises expect line 11 in 100 ms" pin event 49

Checks: user-parameterized "when D1 rises expect line 11 in 100 ms" pin event source code 50

Checks: user-parameterized "when D1 rises expect line 11 in 100 ms" pin event source code timing 51

Checks: user-parameterized “When D1 rises, expect Line 17 in 20 ms” 52

Checks: user-parameterized “When D1 rises, expect Line 17 in 20 ms” 53

Checks: user-parameterized “When D1 rises, expect Line 17 in 20 ms” 54

Evaluation How effectively does Bifröst aid embedded debugging? 55

Evaluation: issues Users identified issues such as: pin misconfiguration thresholding issues switch bouncing timing issues 56

Evaluation: strategies Users identified these issues using: variable/signal data comparison code statement execution monitoring automatic and user-inferred checks 57

Limitations performance: instrumentation overhead (full speed to under 10x) scope: only instruments user code and Arduino core functions 58

Future Work • Support for continuous capture • Support for multiple devices • Checking & visualizing networked behavior 59

Thanks! Will McGrath – wmcgrath@stanford.edu Jeremy Warner – jeremy.warner@berkeley.edu With: Daniel Drew, Mitchell Karchemsky, Majeed Kazemitabaar, David Mellis, and Björn Hartmann