implementing a digital stopwatch using basic stamp2

IMPLEMENTING A

DIGITAL STOPWATCH USING BASIC STAMP II

MAE 576 [MECHATRONICS] LAB-1GROUP E

Chembrammel Elavunkal Srinivasan Vishwajeet

University at Buffalo, Mechatronics, Spring 2010

2

INTRODUCTION

Implement a digital stopwatch on Liquid Crystal Display (LCD)

The components used and their functioning are The circuit used for the implementation is

drawn The code controlling the hardware is included

to complement the understanding of the functioning of the stopwatch

The accuracy of the stopwatch is discussed Solution to improve the accuracy is proposed.


3

OBJECTIVES


Gain familiarity with BS2 programming environment.

Implement digital inputs from a keypad Perform digital outputs to a seven-segment

display Interface a LCD display as a digital stopwatch.

4

HARDWARE OVERVIEW


Basic Stamp 2 (Rev. J) Module Professional Development Board 2 x 16 Parallel LCD

5

HARDWARE OVERVIEW


Professional Development Board (PDB) A Power switch L

L293D high-current quad half-H driver

B2.1 mm power connection,

centre positive, input voltage 6-12 VDC

MEight active-low push-

buttons with 5V pull-ups

CSerial programming

interface, DB-9N

Eight active-low DIP switches with 5V pull-ups

DBS1-IC, BS2-224, BS2-40

and Javelin Stamp socketsO

Pulse generator with 1Hz, 10Hz, 100Hz and 1 kHz

selectable output

EBS1 Serial Adapter

connectionP

RJ-11 connector for X-10 or 1-Wire I/O

F Sixteen blue discrete LEDs QMAX232E RS-232 DCE line

driver

GFive blue 7-segment LED

displaysR

DS1307 I2C real-time clock with 3V battery backup

HParallel LCD interface with contrast pot (4/8-bit modes

supported)S SX28AC/DP socket

I

Two servo headers (can also be used for Parallax Serial LCD displays and PING)))

sensor)

TSX-Key/SX-Blitz

programming connection

J Two 10K potentiometers USolderless breadboard for

connecting external components

KAudio amplifier with volume

control (speaker on-board/ext selectable)

6

HARDWARE OVERVIEW


Basic Stamp 2 (Rev. J) Module

7

HARDWARE OVERVIEW


EEPROM

Regulator

InterpreterPIC16F57

Name BS2-IC

Package 24-pin DIP

Package Size (L x W x H) 1.2"x0.6"x0.4"

Environment-40 to +185 oF (-40 to

+85 oC) **

Processor Speed 20 MHz

Program Execution Speed ~4,000 instructions/sec.

RAM Size 32 Bytes (6 I/O, 26 Variable)

Scratch Pad RAM N/A

EEPROM (Program) Size 2K Bytes, ~500 instructions

Number of I/O pins 16 +2 Dedicated Serial

Voltage Requirements 5 - 15 vdc

Current Draw @ 5V 3 mA Run / 50 µA Sleep

Source / Sink Current per I/O 20 mA / 25 mA

Source / Sink Current per unit 40 mA / 50 mA per 8 I/O pins

PBASIC Commands 42

PC Programming Interface Serial Port (9600 baud)

Windows Text Editor Stampw.exe (v1.04 and up)

[i] http://www.parallax.com/tabid/134/List/1/ProductID/1/Default.aspx

Basic Stamp 2 (Rev. J) Module

http://www.parallax.com/tabid/134/List/1/ProductID/1/Default.aspx

8

HARDWARE USED


Component Name

On PDBY/N

Part # Page #

BS2 – IC Y Basic Stamp2 Module 9

PDB -Professional

Development Board3

Switches* Y [M] 6

LED Y [F] 6

7-segment Display

Y [G] 5

Piezo Beeper Y [K] 8

LCD Display N 2 x 16 Parallel LCD 11

9

HYPOTHESIS


When 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 SOLUTION


Integrate part A-D of experiments to obtain functionality of stopwatch

Develop a flow chart to get better understanding of process

Create circuit layout to integrate all necessary hardware

Program code to ensure full operation spectrum

Implement finished digital system

11

CONSTRAINTS [Self Imposed]


Ensure clean hardware implementation Reduce use of hardware resources Streamline coding to achieve optimal

functionality Test and achieve maximum timer

accuracy Welcome Message Status gesture to indicate operation

Additional Goals

12

PROCEDURE


Experiment- Part # Component NameDigital Stopwatch Implementation

Part A(Turn LED ON/OFF)

Switch & LEDS1 – LED7 FLASHES

S2 – LED7 OFFS3 – LED7 ON

Part B (Interfacing 7-

segment Display)7-segment Display

S1 – display “1”S2 – display “2”S3 – display “3”

Part C(Interfacing LCD

Screen)LCD Screen

Display Welcome message

Display Time

Part D(Piezo Beeper)

Piezo BeeperS1 – tone1 (repeat)

S2 – tone2S3 – tone3

Experiments A - D

13

PROCEDURE [Flow Chart]


Flow Chart

14

PROCEDURE [Circuit]


Circuit

15

PROCEDURE [Pin Layout]


Pin Layout

PIN # Component Device

P0 D4 LCD Data Input




P4 E LCD Pulse Input

P5 RS LCD Command/Write

P6 Speaker Piezo Beeper

P7 Seg -A Segment A of 7 Segment

P8 Seg - C Segment C of 7 Segment

P9 Seg - D Segment D of 7 Segment

P10 Seg - E Segment E of 7 Segment

P11 Seg - G Segment G of 7 Segment

P12 LED LED O/P

P13 Button0 S1 (Button)



16

PROCEDURE [Source Code]


Source Code (Attached to Webpage)

Please note the source code to run the digital stopwatch is attached to this website for your convenience

USED:38% of the

EEPROM5 registers

17

PROCEDURE [Special Connections]


Component Name Pin # Connection*

LCD R/W VSS GND (Voltage LOW)

7 – Segment Display FOpen

(Since digits 1,2,3 do not use F)

7 – Segment Display BVDD

(Since B segment is always ON)

7 – Segment Display Digit0VSS GND (Voltage LOW)

(To enable display)

*These connections should always be ensured for proper operation of the system

IMPLEMENTATION


18

7-segment Display

LED7

Power Switch/Ligh

t

Piezo Beeper

LCD

S1S2S3

19

CALIBRATION


Coarse Delay

(milliseconds)

Fine Delay

(milliseconds)

Total Delay

(milliseconds)

Reference Clock

(hh:mm:ss)

BS2 Stopwatch(hh:mm:ss

)

Error%

850 0 850 00:03:00 00:02:59 -0.5%

840 5 845 00:12:39 00:12:38 -0.01%

840 4 844 00:22:52 00:22:52 0%

840 3 843 00:12:02 00:12:03 0.01%

Coarse delay and Fine delay tuning mechanism to be able to manually adjust the timing operation

20

TESTING


Test Case No.

Time elapsed on Digital Stopwatch(hh:mm:ss)

Time elapsed on reliable time source

(hh:mm:ss)

Difference in time( s)

1. 00:01:00 00:01:00 0±0.5

2. 00:02:00 00:02:00 0±0.5

3. 00:03:00 00:03:00 0±0.5

4. 00:04:00 00:04:00 0±0.5

5. 00:05:00 00:05:00 0±0.5

6. 00:10:00 00:10:00 0±0.5

7. 00:15:00 00:15:00 0±0.5

8. 00:20:00 00:20:00 0±0.5

9. 00:25:00 00:25:00 0±0.5

10. 00:30:00 00:30:00 0±0.5

11. 00:45:00 00:45:00 0±0.5

12. 01:00:00 01:00:00 0±0.5

Test Case No.

Time elapsed on Digital Stopwatch(hh:mm:ss)

Time elapsed on reliable time source

(hh:mm:ss)

Difference in time( hh:mm:ss)

1. 00:10:00 00:10:00 0±0.52. 00:30:00 00:30:00 0±0.53. 01:00:00 01:00:00 0±0.54. 02:00:00 02:00:00 0±0.55. 03:00:00 02:59:59 1.0±0.5

1 second every 3 hours

21

ERRORS


0 5 10 15 20 250

5

10

15

20

25 Error Plot

Reference Time (s)

Sto

pw

atc

h T

ime

(s)

22

ERROR ESTIMATION


0 10 20 30 40 50 60 70 800

5

10

15

20

25

30

f(x) = 0.333333333333333 x

Error Estimation - II

Time (hr)

Err

or

(s)In simple terms there is an

error of 0.333s introduced every 60 minutes operation of the stopwatch timing

23

CONCLUSION


Able to implement the digital stopwatch using BS2 microcontroller

Familiarized aspects of integrating multiple electronic components and program them

Implemented the digital stopwatch with accuracy using minimum number of electronic components

Laid emphasis compact design 38% of the total EEPROM due to good programming

practice Calibration process yielded combined “Coarse & Fine”

delay of 844ms Accuracy and precision of ±0.5 seconds

24

REFERENCES


http://www.parallax.com/Store/Education/KitsandBoards/tabid/182/CategoryID/67/List/0/SortField/0/Level/a/ProductID/320/Default.aspx

http://www.parallax.com/tabid/441/Default.aspx BASIC Stamp Syntax and Reference Manual http://www.parallax.com/tabid/214/Default.aspx http://www.parallax.com/tabid/134/List/1/ProductI

D/1/Default.aspx http://www.parallax.com/Portals/0/Downloads/doc

s/prod/audiovis/lcd2x16par.pdf




http://www.parallax.com/tabid/441/Default.aspx

http://www.parallax.com/tabid/214/Default.aspx



http://www.parallax.com/Portals/0/Downloads/docs/prod/audiovis/lcd2x16par.pdf

http://www.parallax.com/Portals/0/Downloads/docs/prod/audiovis/lcd2x16par.pdf

implementing a digital stopwatch using basic stamp2

Technology

mechatronics lab

digital stopwatch

hardware overviewuniversity

digital system

lcd display

digital inputs

stopwatch timing

hardware useduniversity