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NASA-Threads
Electricity and Magnetism Lesson 18: Definitions & Review
Definitions and Examples
At this point you have already had your first quiz, and you are hopefully getting more
comfortable with most of the terms and the language used on your BOE-bot. Here is a quick
review of all the terms you have used so far.
Some of this is borrowed from Wikipedia and Parallax Inc.
Listing of Common PBasic Commands
Command
Description
' comment
An apostrophe at the beginning of a line means that
what follows is a comment, meant to aid readability
and understanding for humans.
' {$STAMP BS2}
' {$PBASIC 2.5}
An exception to the apostrophe-means-comment
rule. These are "compiler directives" that tell the
PBASIC editor what kind of Stamp microcontroller
you're using, and what version of the PBASIC
language the program is written in. These are
required at the beginning of every program.
DEBUG "text" {,CR}
DEBUG DEC variablename
DEBUG ? variablename
Sends text to the PBASIC editor "Debug Terminal"
(window), to aid you in finding problems and fixing
a program (debugging). The optional CR (carriage
return) causes the start of a new line in the Debug
Terminal.
END
Marks the end of the program; stops execution.
PAUSE delay
Causes the program to wait delay milliseconds.
DO...LOOP
Causes all the program lines between the DO and
LOOP to repeat forever.
HIGH pin
Makes pin pin to be set to high, or 5 volts.
LOW pin
Makes pin pin to be set to low, or 0 volts.
PULSOUT pin, duration
Sends a HIGH pulse on pin pin. The duration of the
high pulse is duration times 2 microseconds.
variablename VAR variablesize
Creates a varable called variablename with
size variablesize --- bit, nib (for nibble), byte, or
NASA-Threads
Electricity and Magnetism Lesson 18: Definitions & Review
word.
variablename = value
The equals sign here is not a statement of equality,
as it is usually used in math. Instead, it is an
operator -- it stores the value value into the
variable variablename.
*
Multiplication operator
FOR counter = start TO end {STEP stepsize}...NEXT
Repeats all the lines of code between the FOR and
the NEXT. The first time through, the
variablecounter has the value start. The next time
through counter has the value start+stepsize. This
repeats until the value of counter reaches end. If the
STEP is left out, stepsize defaults to 1.
FREQOUT pin, duration, frequency {, anotherfreq}
Sends an alternating high-low pulse train on pin pin,
for duration milliseconds, with frequency given in
Hertz. This can be used to drive a speaker, making a
musical tone. Optionally, a second tone can be
generated simultaneously.
DEBUGIN DEC variablename
Allows a user to type a decimal value into a running
program from the PBASIC editor over the serial
cable, and that value is stored in the
variable variablename. Useful for testing programs.
GOSUB subroutinename
Jumps the program to the start of a subroutine
subroutinename:
The start of a subroutine is marked by the
subroutine's name (whatever you choose it to be)
followed by a colon (:).
RETURN
This marks the end of a subroutine. When this
statement is reached, the program continues with
the line immediately after the GOSUB that launched
the subroutine.
DATA
Stores data on the EEPROM chip on the BASIC
Stamp.
NASA-Threads
Electricity and Magnetism Lesson 18: Definitions & Review
READ
Retrieves data from the EEPROM chip on the BASIC
Stamp.
SELECT...CASE...ENDSELECT
DO WHILE condition ...LOOP
Execute (run) a series of instructions (where the ...
is) as long as the condition is true. Once the
condition is violated (false), execution continues on
the line after LOOP.
DO...LOOP UNTIL condition
Execute (run) a series of instructions (where the ...
is) until the condition is true. Once the condition is
true, execution continues with the next command.
Source:
Anything in a circuit that provides a positive voltage value, such as a battery
Load:
Anything in a circuit that provides a negative voltage value, that is, it takes voltage away
from the circuit. These include LED’s, light bulbs, etc.
Voltage:
The electrical potential difference across an element of a circuit, represented V.
V=J/C, where J is joules and C is coulombs.
Note: A joule is merely the amount of work done.
Current:
Represented I, measured in amps, also measured in series in a circuit unlike voltage which
is measured in parallel (across a circuit).
A=C/sec, that is, amps = amount of coulombs moved per second.
LED:
Light emitting diode. Simply put, this is a small light bulb.
Resistor:
a two-terminal electronic component that produces a voltage across its terminals that
is proportional to the electric current through it in accordance with Ohm's law
NASA-Threads
Electricity and Magnetism Lesson 18: Definitions & Review
Coulomb:
Represented C. One Coulomb = 6.24*1018 electrons
Kirchhoff’s Voltage Law:
The sum of the voltages in a loop must always equal zero.
In the above figure, according to KVL the sum of the voltages v1+v2+v3+v4=0.
Ohm’s Law:
the current through a conductor between two points is directly proportional to the potential
difference or voltage across the two points, and inversely proportional to
the resistance between them. That is I=V/R or V=IR or R=V/I.