This document describes implementing a digital stopwatch using a Basic Stamp II microcontroller. The objectives are to gain familiarity with the BS2 programming environment, interface a LCD display as a digital stopwatch, and implement digital inputs from a keypad and outputs to a display. The hardware used includes a Basic Stamp II module, development board, and LCD. The procedure involves experiments, a flow chart, circuit design, and programming the stopwatch functionality. Testing achieves a timing accuracy of within 0.5 seconds over 3 hours of operation.

1. IMPLEMENTING A DIGITAL STOPWATCH USING BASIC STAMP IIMAE 576 [MECHATRONICS] LAB-1University at Buffalo, Mechatronics, Spring 2010Chembrammel Elavunkal SrinivasanVishwajeetGROUP E

2. INTRODUCTIONImplement a digital stopwatch on Liquid Crystal Display (LCD) The components used and their functioning areThe circuit used for the implementation is drawnThe code controlling the hardware is included to complement the understanding of the functioning of the stopwatchThe accuracy of the stopwatch is discussedSolution to improve the accuracy is proposed.University at Buffalo, Mechatronics, Spring 20102

3. OBJECTIVESGain familiarity with BS2 programming environment.Implement digital inputs from a keypadPerform digital outputs to a seven-segment displayInterface a LCD display as a digital stopwatch.University at Buffalo, Mechatronics, Spring 20103

4. HARDWARE OVERVIEWBasic Stamp 2 (Rev. J) ModuleProfessional Development Board2 x 16 Parallel LCDUniversity at Buffalo, Mechatronics, Spring 20104

5. HARDWARE OVERVIEWProfessional Development Board (PDB)University at Buffalo, Mechatronics, Spring 20105

6. HARDWARE OVERVIEWUniversity at Buffalo, Mechatronics, Spring 20106Basic Stamp 2 (Rev. J) Module

7. HARDWARE OVERVIEW7[i] http://www.parallax.com/tabid/134/List/1/ProductID/1/Default.aspxBasic Stamp 2 (Rev. J) ModuleEEPROMRegulatorInterpreterPIC16F57University at Buffalo, Mechatronics, Spring 2010

8. HARDWARE USEDUniversity at Buffalo, Mechatronics, Spring 20108

9. HYPOTHESISUniversity at Buffalo, Mechatronics, Spring 20109When Switch S1(part M) is pressed, begin flashing the LED (part F) once per second and continuously display and update the time in seconds on the LCD (not a part of PDB) display. When Switch S2 is pressed, stop the clock and display the elapsed time. If Switch S1 is pressed again, continue counting up while waiting for Switch S2 to be pressed. Switch S3 is used to reset the display. The seven segment display (part G) should flash the number of switch being pressed.

10. PROPOSED SOLUTIONIntegrate part A-D of experiments to obtain functionality of stopwatchDevelop a flow chart to get better understanding of processCreate circuit layout to integrate all necessary hardwareProgram code to ensure full operation spectrumImplement finished digital systemUniversity at Buffalo, Mechatronics, Spring 201010

11. CONSTRAINTS [Self Imposed]University at Buffalo, Mechatronics, Spring 201011Ensure clean hardware implementationReduce use of hardware resourcesStreamline coding to achieve optimal functionalityTest and achieve maximum timer accuracyAdditional GoalsWelcome Message

12. Status gesture to indicate operationPROCEDUREExperiments A - DUniversity at Buffalo, Mechatronics, Spring 201012

13. PROCEDURE [Flow Chart]Flow ChartUniversity at Buffalo, Mechatronics, Spring 201013

14. PROCEDURE [Circuit]CircuitUniversity at Buffalo, Mechatronics, Spring 201014

15. PROCEDURE [Pin Layout]Pin LayoutUniversity at Buffalo, Mechatronics, Spring 201015

16. PROCEDURE [Source Code]University at Buffalo, Mechatronics, Spring 201016Source Code (Attached to Webpage) USED: 38% of the EEPROM 5 registers Please note the source code to run the digital stopwatch is attached to this website for your convenience

17. PROCEDURE [Special Connections]*These connections should always be ensured for proper operation of the systemUniversity at Buffalo, Mechatronics, Spring 201017

18. IMPLEMENTATIONPower Switch/Light7-segment DisplayLED718LCDPiezo BeeperS1S2S3University at Buffalo, Mechatronics, Spring 2010

19. CALIBRATIONCoarse delay and Fine delay tuning mechanism to be able to manually adjust the timing operationUniversity at Buffalo, Mechatronics, Spring 201019

20. TESTING1 second every 3 hoursUniversity at Buffalo, Mechatronics, Spring 201020

21. ERRORSUniversity at Buffalo, Mechatronics, Spring 201021

22. ERROR ESTIMATION22In simple terms there is an error of 0.333s introduced every 60 minutes operation of the stopwatch timingUniversity at Buffalo, Mechatronics, Spring 2010

23. CONCLUSIONUniversity at Buffalo, Mechatronics, Spring 201023Able to implement the digital stopwatch using BS2 microcontrollerFamiliarized aspects of integrating multiple electronic components and program themImplemented the digital stopwatch with accuracy using minimum number of electronic componentsLaid emphasis compact design38% of the total EEPROM due to good programming practiceCalibration process yielded combined “Coarse & Fine” delay of 844msAccuracy and precision of ±0.5 seconds

24. REFERENCEShttp://www.parallax.com/Store/Education/KitsandBoards/tabid/182/CategoryID/67/List/0/SortField/0/Level/a/ProductID/320/Default.aspxhttp://www.parallax.com/tabid/441/Default.aspxBASIC Stamp Syntax and Reference Manualhttp://www.parallax.com/tabid/214/Default.aspxhttp://www.parallax.com/tabid/134/List/1/ProductID/1/Default.aspxhttp://www.parallax.com/Portals/0/Downloads/docs/prod/audiovis/lcd2x16par.pdfUniversity at Buffalo, Mechatronics, Spring 201024