Datasheet

Page 12· Applied Robotics with the SumoBot

DEBUG "Main program running...", CR ' Display program status

' -----[ Main Routine ]-------------------------------------------------------

FOR counter = 1 TO 100 ' Deliver 100 forward pulses

PULSOUT ServoLeft, 850

PULSOUT ServoRight, 650

PAUSE 20

DEBUG "Done!", CR, ' User instructions

"Press/release reset", CR,

"twice to restart...", CR

END

Understanding Forward100Pulses.bs2

When you click the BASIC Stamp Editor's Run button, the program downloads to the

SumoBot's BASIC Stamp. The

Reset_Button routine in the Initialization displays the

message "Press/release Reset...", then it ends the program. When you press and release

the Reset button on the SumoBot board, the same

Reset_Button routine displays the

message "Main program running..." and moves on to the Main Routine and the servos

start turning. If you leave the SumoBot connected to its serial cable and press/release the

Reset button a third time, you will again see the "Press/release Reset button" prompt.

Repeat a fourth time, and the servos will run for a couple seconds.

The reason the

Reset_Button routine is able to perform this function is because it

manipulates values stored in the SumoBot's EEPROM program memory. The portion of

this memory that is not used to store the program can be used to store values. While the

BASIC Stamp's RAM memory is erased whenever the power is turned off or the Reset

button is pressed and released, the EEPROM memory retains the values stored in it.

That's why the same program runs after your turn the SumoBot's power off, then back on.

The ability to retrieve values stored in EEPROM, change them, and store them back into

EEPROM is what allows the

Reset_Button routine to track whether you've pressed and

released the Reset button an odd or even number of times. The mechanics of exactly how

the

Reset_Button routine does this is covered in more detail in Chapter 2, Activity #2.

For now, just keep in mind that the

Reset_Button routine allows the program to

continue to the Main Routine when you have pressed and released the SumoBot's Reset

button an odd number of times. That means, the first, third, fifth,... time you press and

release the Reset button, the program will continue to the Main Routine, and the servos

will turn for about 2 1/2 seconds. Whenever you have pressed/released the Reset button