CEC450 Real-Time Systems

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1 CEC450 Real-Time Systems Lecture 15 Block Diagram Design Examples November 3, 2015 Sam Siewert

2 Design Elements for Proof-of-Concept Top N Capability Oriented Requirements State and Explain Hold Q&A and Ask for Reviewer Input on Completeness, Errors and Omissions Top N Real-Time Requirements [C i, T i, D i or each S i ] State and Explain Service request frequency drivers and relative deadlines How did you estimate or measure C i WCET Single Page High Level Block Diagram of Software System Show End-to-End Elements and Dataflow Source to Sink (Top Left Corner to Bottom Right) CFD/DFD, Flow Charts, State Machines or Other Design Models Proof-of-Concept Time-Stamp Tracing Analysis Sam Siewert 2

3 Design Example STS-85 Payload (Flown 1997, U. of Colorado) Sam Siewert 3

4 Payload Operations 1. The Embedded System Shall Operate 3 Instruments (LASIT, SXEE, FARUS) According to a Scheduled Observing Plan of the Sun within STS Imposed Constraints 2. The Health & Status of Each Instrument Shall be Reported to the Ground Continuously 3. Science Data Collected by Each Instrument Shall be Streamed to the Ground While an Instrument is Observing 4. Observing Plan Updates Can be Uplinked from the Ground Systems as Command(s) with Response 5. Commands to Operate Instruments Interactively Can be Uplinked from the Ground and Status Indication Response Will be Provided 6. The Embedded System Must Interface to Low-Rate Uplink and Downlink interfaces on STS for Command/Response, H&S Telemetry Streaming 7. The Ground Software at GSFC Must Interface to the ACCESS LRDU 8. Telemetry Must be Stored in a Time-stamped Database 9. A HMI GUI Must Display H&S Telemetry at GSFC and Provide a Command/Response Interface 10. GSFC Ground Systems Must Host a Planning and Operations Rules and Constraints Database and Engine 11. GSFC Ground Systems Must Host H&S Telemetry Monitoring to Detect Anomalous Behavior to Generate Alerts for the HMI/GUI 12. A Data Bridge Between GSFC Ground Systems and CU Boulder Must Provide a Command/Response and H&S Telemetry Network Interface 13. CU Boulder Ground Systems Must Interface an Automated Planning and Scheduling Software Application and Allow it to Generate Uplink Commands to Modify or Replace the Current Embedded System Observing Plan 14. The CU Boulder Ground Systems Must Provide and HMI/GUI for H&S Telemetry, Command/Response and Automated Planning and Scheduling 15. A CU Boulder to NASA JPL Data Bridge Must Provide H&S Telemetry for Beacon Monitoring to NASA JPL for Display on a High Level Status HMI/GUI Sam Siewert 4

5 Hardware End-to-End System DATA Hitchhiker Payload, flown STS-85, Summer 1997 Designed, Built and Operated by U. of Colorado Students Sam Siewert 5

6 Software End-to-End System Sam Siewert 6

7 SE300 RT Design Models Examples from SE300 (Specific to Real-Time Design) Sam Siewert 7

8 Real Time Systems Design transformational processes, representing computations or information processing activities control processes, representing system s state dependent behavior, which is modeled by a Mealy type state machine continuous data flow, which must be processed in real time ordinary or discrete data flow event flow or control flow that triggers a transition of the state machine of a control process, or a command from a control process to a transformational process Copyright {c} 2014 by the McGraw-Hill Companies, Inc. All rights Reserved. 13-8

9 Real Time Systems Design a b P indicates that both data flow a and data flow b are required to begin executing process P a + b P indicates that either data flow a or data flow b is required to begin executing process P These logical connector can be applied to both data flow and control flow and transformation process and control process. Copyright {c} 2014 by the McGraw-Hill Companies, Inc. All rights Reserved. 13-9

10 Z Z X Y Real Time Systems Design Two subsets of Z are used by two different successor processes. All of Z is used by two different successor processes. X Y Z Z is composed of Two subsets provided by two different predecessor processes. Z All of Z is provided by either one of two predecessor processes. Copyright {c} 2014 by the McGraw-Hill Companies, Inc. All rights Reserved

11 CFD/DFD Cruise Control Example enable/disable rotation rate throttle control start/stop increase speed Increase Speed throttle position brake enable/ disable throttle control Cruise Control resume trigger enable/ disable enable/ disable Maintain Constant Speed rotation rate speed reached throttle position Record Rotation Rate Return to Previous Speed rotation rate set point rotation rate throttle control rotation rate throttle position Copyright {c} 2014 by the McGraw-Hill Companies, Inc. All rights Reserved.

12 enable[] / trigger RRR; enable MCS disable[] / disable MCS Maintain Speed brake[] / disable MCS start increase speed[] / disable MCS; enable IS stop increasing speed[] / disable IS; trigger RRR; enable MCS Increase Speed brake[] / disable IS Interrupted resume[] / enable RPS brake[] / disable RPS speed reached[] / disable RPS; enable MCS Sam Siewert Resume Speed Copyright {c} 2014 by the McGraw-Hill Companies, Inc. All rights Reserved.

SE310 Analysis and Design of Software Systems

SE310 Analysis and Design of Software Systems Lecture 11 Presentation of Analysis and Design [Level-0,1,2,3] March 21, 2018 Sam Siewert Reminders Assignment #5 Assignment #5 & #6 Posted Questions? Exercise