The chip and the pendulum

The program The program asks you to press 'P' to start the ball rolling. When prompted simply set the pendulum in motion. This will call the procedure PROCfind_zero  at line 850 which records the swing of the pendulum for 2 seconds, finds the highest and lowest value and from this the average, with is the zero line. This should make allowances for different settings of the  Velleman board ADC potentiometer as well as for all other variables and hopefully put the first trace at the top of the screen. The next procedure called is PROCgoing_north   at line 1070. This waits for one swing to go negative and then waits for the zero line to be crossed before plotting begins. This routine is called at the beginning of every new line, thus making sure that the traces all start at the same point. This makes sure that they all line up rather nicely. PROCswing  will then look after the rest of the business. You can press 'H' at any time to return to the menu so that a new trace can be started from scratch. Here is an archive with both the program code and a stand-alone exec file. K8055_chip-and-pendulum.zip and here is the YouTube video of this project And here are the same two files for the K8061 K8061_chip-and-pendulumnew.bbc K8061_chip-and-pendulum.exe

10 REM K8055_chip-and-pendulum    20    30 REM Demonstrate the mysteries of a pendulum    40 REM Needs a functioning Velleman K8061 extended USB Experiment Interface board    50 REM and a large tower if pendulum is longer than a few metres.    60 REM Jochen Lueg    70 REM http://roevalley.com    80 REM Limavady, February 2012    90 REM Issue 3.2   100   110   120 ON ERROR PRINT REPORT$;"  ";ERL:END   130 MODE 28   140 COLOUR 128   150 CLS   160 COLOUR15   170   180 PROCK8055_init   190 PROCinit   200 SYS K8055_CloseDevice%   210 SYS K8055_OpenDevice%,1   220 PROCprint_menu   230   240 REPEAT   250   Key$=INKEY$(0)   260   IF Key$= "p" OR Key$= "P" PROCswing   270 UNTIL Key$="q" OR Key$="Q"   280   290 SYS K8055_CloseDevice%   300 SYS "FreeLibrary",K8055_Board%   310 *QUIT   320 END   330   340   350 DEFPROCprint_menu   360 VDU 4   370 CLS   380 PRINT   390 PRINT " Please select one of the following"   400 PRINT   410 PRINT " Plot the movement of the pendulum  . . . . . . . .  P"   420 PRINT   430 PRINT " Quit this program  . . . . . . . . . . . . . . . .  Q"   440 PRINT   450 ENDPROC   460   470   480 DEFPROCswing   490 LOCAL A%,Key$   500 PRINT " Please set pendulum swinging."   510 PRINT " Press H to return to the main menu at any time"   520 PRINT " It will take 3 seconds for the plotting to start."   530 REPEAT   540   SYS K8055_ReadAnalogChannel%,1 TO V1%   550   TIME=0:REPEAT UNTIL TIME >20   560   SYS K8055_ReadAnalogChannel%,1 TO V2%   570 UNTIL V2%>V1%+4 OR V2%<V1%-4   580 PROCfind_zero   590 PROCgoing_north(10)   600 VDU 5   610 CLG   620 MOVE 0,1900   630 FORI%=5 TO 6   640   GCOL I%   650   FOR Y%= 1900 TO 600 STEP -250   660     PROCgoing_north(2)   670     REM Start plotting   680     FOR X%= 0 TO 2879   690       SYS K8055_ReadAnalogChannel%,1 TO V%   700       PLOT 5,X%,Y%+(V%-ZeroPoint%)*6   710       Key$=INKEY$(0):IF Key$= "h" OR Key$= "H" PROCprint_menu:ENDPROC   720     NEXT   730     MOVE 0,Y%-200   740   NEXT   750 NEXT   760 GCOL 15   770 MOVE 20,2200   780 PRINT " Press any key to return to the main menu"   790 A%=GET   800 REPEAT UNTIL INKEY(0)=-1   810 PROCprint_menu   820 ENDPROC   830   840

850 DEFPROCfind_zero   860 LOCAL High%,Low%   870 High%=0   880 Low%=10000   890 REPEAT   900   SYS K8055_ReadAnalogChannel%,1 TO V1%   910   TIME=0: REPEAT UNTIL TIME>10   920   SYS K8055_ReadAnalogChannel%,1 TO V2%   930 UNTIL V2% > V1%   940 TIME=0   950 REPEAT   960   SYS K8055_ReadAnalogChannel%,1 TO V%   970   IF V%>High% THEN High%=V%   980 UNTIL TIME>100   990 REPEAT  1000   SYS K8055_ReadAnalogChannel%,1 TO V%  1010   IF V%<Low% THEN Low%=V%  1020 UNTIL TIME>200  1030 ZeroPoint%=(Low%+High%)/2  1040 ENDPROC  1050  1060  1070 DEFPROCgoing_north(l%)  1080 REPEAT  1090   Key$=INKEY$(0)  1100   SYS K8055_ReadAnalogChannel%,1 TO V%  1110 UNTIL V%<ZeroPoint%-l% OR Key$="h" OR Key$="H"  1120 REPEAT  1130   Key$=INKEY$(0)  1140   SYS K8055_ReadAnalogChannel%,1 TO V%  1150 UNTIL V%>=ZeroPoint%+l%  OR Key$="h" OR Key$="H"  1160 ENDPROC  1170  1180  1190 DEFPROCinit  1200 Mode%=MODE  1210 Offset%=0  1220 ZeroPoint%=100  1230 ENDPROC  1240  1250  1260  1270 DEFPROCK8055_init  1280 REM  Typing errors in routine name do not generate an error message - they just hang up the program.  1290 REM These are all the system calls in the order found in the manual  1300 SYS"LoadLibrary","K8055D.dll" TO K8055_Board%  1310 SYS"GetProcAddress",K8055_Board%,"OpenDevice" TO K8055_OpenDevice%  1320 SYS"GetProcAddress",K8055_Board%,"CloseDevice" TO K8055_CloseDevice%  1330 SYS"GetProcAddress",K8055_Board%,"ReadAnalogChannel" TO K8055_ReadAnalogChannel%  1340 SYS"GetProcAddress",K8055_Board%,"ReadAllAnalog" TO K8055_ReadAllAnalog%  1350 SYS"GetProcAddress",K8055_Board%,"OutputAnalogChannel" TO K8055_OutputAnalogChannel%  1360 SYS"GetProcAddress",K8055_Board%,"OutputAllAnalog" TO K8055_OutputAllAnalog%  1370 SYS"GetProcAddress",K8055_Board%,"ClearAnalogChannel" TO K8055_ClearAnalogChannel%  1380 SYS"GetProcAddress",K8055_Board%,"ClearAllAnalog" TO K8055_ClearAllAnalog%  1390 SYS"GetProcAddress",K8055_Board%,"SetAnalogChannel" TO K8055_SetAnalogChannel%  1400 SYS"GetProcAddress",K8055_Board%,"SetAllAnalog"  TO K8055_SetAllAnalog%  1410 SYS"GetProcAddress",K8055_Board%,"WriteAllDigital" TO K8055_WriteAllDigital%  1420 SYS"GetProcAddress",K8055_Board%,"ClearDigitalChannel" TO K8055_ClearDigitalChannel%  1430 SYS"GetProcAddress",K8055_Board%,"ClearAllDigital" TO K8055_ClearAllDigital%  1440 SYS"GetProcAddress",K8055_Board%,"SetDigitalChannel" TO K8055_SetDigitalChannel%  1450 SYS"GetProcAddress",K8055_Board%,"SetAllDigital"  TO K8055_SetAllDigital%  1460 SYS"GetProcAddress",K8055_Board%,"ReadDigitalChannel" TO K8055_ReadDigitalChannel%  1470 SYS"GetProcAddress",K8055_Board%,"ReadAllDigital"  TO K8055_ReadAllDigital%  1480 SYS"GetProcAddress",K8055_Board%,"ResetCounter"  TO K8055_ResetCounter%  1490 SYS"GetProcAddress",K8055_Board%,"ReadCounter"  TO K8055_ReadCounter%  1500 SYS"GetProcAddress",K8055_Board%,"SedtCounterDebouceTime"  TO K8055_SetCounterDebounceTime%  1510 ENDPROC