When an engineer or technician is using a Tektronix oscilloscope, they often have both hands busy probing a circuit board. Sometimes they need a “third hand” to operate the Oscilloscope. This need can cause some users to create Rube Goldberg type machines to manually press buttons, employ another operator to run the Oscilloscope, or find creative ways to tape down probes to free up hands. Without a solution, it can take users much longer to test circuits and collected required data.

Our solution to this problem is to implement a footswitch that will act as a third hand to control the Oscilloscope. (This was proposed as a capstone project for 2010)

The goal of this project is to design and build a working prototype of a footswitch and a software GUI that successfully integrates the footswitch with various Tektronix Oscilloscope. An ideal design would: Be able to communicate with any Tektronix Oscilloscope. Have multiple user configurable commands. Have a minimum of 2 foot controls. Have USB 2.0 interface. An individual momentary button’s functionality is expand by creating multiple mouse button type interaction. Separate actions include a short click, a long click and a double click. Both buttons may be pressed simultaneously. A 3 rd On/Off type button is included, giving a total of 9 possible user input actions.

Design Schedule WBSPredecessors% CompleteDurationStartFinishAssigned team membersTask Name 1100%62 days?Mon 10/3/11Sat 12/3/11All teamProject report %8 daysMon 10/3/11Mon 10/10/11All team Project proposal %4 daysMon 10/3/11Thu 10/6/11All team Choosing project %4 daysFri 10/7/11Mon 10/10/11All team Writing proposal %7 daysThu 10/13/11Wed 10/19/11Jason Project requirements 1.35FS+18 days100%7 daysMon 11/7/11Sun 11/13/11All team System design and modeling %7 daysMon 11/7/11Sun 11/13/11All team System block diagram %3 daysMon 11/7/11Wed 11/9/11Hung Footswitch block diagram %4 daysThu 11/10/11Sun 11/13/11Chris and Jason Whole system and GUI %3 daysThu 11/10/11Sat 11/12/11Hung Footswitch UML - State Machine %3 daysThu 11/10/11Sat 11/12/11Huy Footswitch UML - Activity view %5 daysThu 11/24/11Mon 11/28/11All team Test plan %2 daysThu 11/24/11Fri 11/25/11Huy Write test plan %3 daysSat 11/26/11Mon 11/28/11All team Write test cases 1.516FS-6 days100%1 dayMon 11/28/11 Chris Register for review time slot %1 day?Sat 12/3/11 All team Project presentation 23100%55 daysFri 10/7/11Wed 11/30/11All teamDesign %18 daysFri 10/7/11Mon 10/24/11All team Research %6 daysFri 10/7/11Wed 10/12/11All team Pre-research %13 daysFri 10/7/11Wed 10/19/11All team Interface research %7 daysThu 10/13/11Wed 10/19/11Huy and Hung Micro-controller research %5 daysThu 10/20/11Mon 10/24/11Chris Sampling intervals %49 daysThu 10/13/11Wed 11/30/11Chris and Jason PC Software design %20 daysThu 10/20/11Tue 11/8/11Chris USB interface %49 daysThu 10/13/11Wed 11/30/11Jason Design GUI %13 daysThu 10/20/11Tue 11/1/11All team Build test circuit %3 daysThu 10/20/11Sat 10/22/11Hung Test schematic %4 daysSun 10/23/11Wed 10/26/11All team Build test circuit %10 daysSun 10/23/11Tue 11/1/11Hung ATmega8 program testing %14 daysSun 10/23/11Sat 11/5/11Hung Schematic %3 daysSun 10/23/11Tue 10/25/11Hung Select components %3 daysWed 10/26/11Fri 10/28/11Hung Finish schematic %8 daysSat 10/29/11Sat 11/5/11Hung Revew and make changes if needed %15 daysSat 10/29/11Sat 11/12/11All team Layout %2 daysSat 10/29/11Sun 10/30/11Huy First draft layout %8 daysMon 10/31/11Mon 11/7/11Chris Final layout %5 daysTue 11/8/11Sat 11/12/11Jason Review layout with TA %22 daysWed 11/2/11Wed 11/23/11Hung Device software %5 daysWed 11/2/11Sun 11/6/11Hung Port test program to real one SS+2 days100%20 daysFri 11/4/11Wed 11/23/11Hung Design ATmega8 program %31 daysWed 11/2/11Fri 12/2/11All teamTest %6 daysWed 11/2/11Mon 11/7/11Hung Timing detection on prototype %4 daysTue 11/29/11Fri 12/2/11All team Test device with test plan %20 daysSun 11/13/11Fri 12/2/11All teamImplementation %4 daysSun 11/13/11Wed 11/16/11Chris Order boards %1 daySun 11/13/11 Chris Create Gerber files %1 dayMon 11/14/11 Chris Create Sunstone account %2 daysTue 11/15/11Wed 11/16/11Chris Order boards on Sunstone 4.245SS+2 days100%4 daysTue 11/15/11Fri 11/18/11All team Order components 4.345FS+6 days100%3 daysWed 11/23/11Fri 11/25/11All team Solder boards %3 daysSat 11/26/11Mon 11/28/11Hung Porting the develop program on the device %4 daysTue 11/29/11Fri 12/2/11Jason Finish physical parts

Long vs. Short vs. Double To determine pulse width times, we collected 30+ samples of each type of action each, for 4 different users. This data was collected on an Oscilloscope using a data logging program. Next a python script analyzed each set of waveforms to find the pulse widths and spacing for each interaction. Using Matlab to plot standard distributions of the results, the optimal values for pulse width duration for a short vs. a long click is and pulse space for a double click vs. two single click was derived. A short pulse is defined as less than 365mS pulse width. For double clicks, 275 spacing or less between two clicks is defined as a double. Because a action will be tied to a scope control command that may take several seconds to complete, it is less likely that the input action will be separate repeat clicks for the same command.

System Model Level 1

GUI Software Model Level 1

Footswitch Model Level 1