Parallax BASIC Stamp II User manual

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 1
BASIC Stamp II
Thank you for purchasing the BASIC Stamp Programming Package.
This is the manual for our new BASIC Stamp II module (shown above).
Everything you need to know about programming the Stamp II may
be found in this manual. However, even if you’re only interested in the
Stamp II, you may gain useful knowledge by referring to the Stamp I
manual. The Stamp I manual has a collection of interesting application
notes, which may only need slight modification to run on the Stamp II.
If you have any questions, please let us know.

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BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 3
BASIC Stamp II
Hardware Setup ..................................................................... 5
System Requirements ............................................................................ 5
Packing List............................................................................................ 5
Connecting to the PC.............................................................................. 6
Carrier Board Features............................................................. 6
BS2-IC Pinout ........................................................................ 7
Using the Editor ..................................................................... 8
Starting the Editor .................................................................................. 8
Entering & Editing Programs.................................................................. 9
Editor Function Keys............................................................................... 9
BASIC Instruction Summary...................................................... 11
Programming the Stamp II ....................................................... 14
Program and Data Memory .................................................................. 14
Defining variables (VAR) ...................................................................... 17
Defining constants (CON)..................................................................... 20
Defining data (DATA) ............................................................................ 21
Run-time expressions .......................................................................... 23
BASIC Instructions .................................................................27
BRANCH ............................................................................................... 27
BUTTON ............................................................................................... 28
COUNT ................................................................................................. 29
DEBUG ................................................................................................. 30
DTMFOUT............................................................................................. 32
END ...................................................................................................... 33
FOR...NEXT........................................................................................... 34
FREQOUT ............................................................................................. 35
GOSUB ................................................................................................. 36
GOTO.................................................................................................... 37
HIGH..................................................................................................... 38
IF...THEN............................................................................................... 39
INPUT................................................................................................... 40
LOOKDOWN ......................................................................................... 41
LOOKUP ............................................................................................... 42
LOW ..................................................................................................... 43
NAP ...................................................................................................... 44
OUTPUT ............................................................................................... 45
PAUSE .................................................................................................. 46
PULSIN................................................................................................. 47
PULSOUT ............................................................................................. 48
PWM .................................................................................................... 49

Page 4 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
RANDOM.............................................................................................. 50
RCTIME ................................................................................................ 51
READ.................................................................................................... 52
RETURN ............................................................................................... 53
REVERSE.............................................................................................. 54
SERIN................................................................................................... 55
SEROUT ............................................................................................... 59
SHIFTIN................................................................................................ 62
SHIFTOUT............................................................................................. 63
SLEEP................................................................................................... 64
STOP .................................................................................................... 65
TOGGLE................................................................................................ 66
WRITE .................................................................................................. 67
XOUT.................................................................................................... 68
Stamp II Application Notes....................................................... 69
Note 1: Controlling lights and appliances with X-10 (XOUT) ................ 69
Note 2: Using SHIFTIN and SHIFTOUT ................................................. 75

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 5
BASIC Stamp II
System Requirements
To program Stamp IIs, you’ll need the following computer system:
•IBM PC or compatible computer
• 3.5-inch disk drive
• Serial port
• 128K of RAM
• MS-DOS 2.0 or greater
To power the Stamps, you can use a 9-volt battery (this is the most
convenient method). You can also use a 5-15 volt power supply, but
you should be careful to connect the supply to the appropriate part of
the Stamp. A 5-volt supply should be connected directly to the Stamp’s
+5V pin (also called VDD), but a higher voltage should be connected
to the Stamp’s PWR pin (also called VIN).
Connecting a high voltage supply (greater than 6 volts) to the 5-volt
pin can permanently damage the Stamp.
Packing List
If you purchased the Stamp Programming Package, you should have
received the following items:
• Stamp I programming cable (parallel port DB25-to-3 pin)
• Stamp I manual
• Stamp I application notes (contained in Stamp I manual)
• Stamp II programming cable (serial port DB9-to-DB9)
• Stamp II manual (this booklet)
• 3.5-inch diskette
If any items are missing, please let us know.

Page 6 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
Connecting to the PC
To program a Stamp II, you’ll need to connect it to your PC and then
run the editor/downloader software. In this booklet, it’s assumed that
you have a BS2-IC and its corresponding carrier board (shown below).
To connect the Stamp II to your PC, follow these steps:
1) Plug the BS2-IC onto the carrier board. The BS2-IC plugs into
a 24-pin DIP socket, located in the center of the carrier. When
plugged onto the carrier board, the words “Parallax BS2-IC”
should be near the reset button.
2) In the Stamp Programming Package, you received a serial cable
to connect the Stamp II to your PC. Plug the female end into
an available serial port on your PC.
3) Plug the male end of the serial cable into the carrier board’s
serial port.
4) Supply power to the carrier board, either by connecting a
9-volt battery or by providing an external power source.
BS2-IC
Socket
I/O
Header
I/O
Header
Prototyping
Area
Reset
Button
9-volt
Battery
Clips
RS-232
Serial
Port

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 7
BASIC Stamp II
Pin Name Description Comments
1 TX Serial output Connect to pin 2 of PC serial DB9 (RX) *
2 RX Serial input Connect to pin 3 of PC serial DB9 (TX) *
3 ATN Active-high reset Connect to pin 4 of PC serial DB9 (DTR) *
4 GND Serial ground Connect to pin 5 of PC serial DB9 (GND) *
5 P0 I/O pin 0 Each pin can source 20 ma and sink 25 ma.
6 P1 I/O pin 1
7 P2 I/O pin 2 P0-P7 and P8-P15, as groups, can each
8 P3 I/O pin 3 source a total of 40 ma and sink 50 ma.
9 P4 I/O pin 4
10 P5 I/O pin 5
11 P6 I/O pin 6
12 P7 I/O pin 7
13 P8 I/O pin 8
14 P9 I/O pin 9
15 P10 I/O pin 10
16 P11 I/O pin 11
17 P12 I/O pin 12
18 P13 I/O pin 13
19 P14 I/O pin 14
20 P15 I/O pin 15
21 +5V ** +5V supply 5-volt input or regulated output.
22 RES Active-low reset Pull low to reset; goes low during reset.
23 GND System ground
24 PWR ** Regulator input Voltage regulator input; takes 5-15 volts.
* For automatic serial port selection by the Stamp II software, there must also be a connection
from DSR (DB9 pin 6) to RTS (DB9 pin 7). This connection is made on the Stamp II carrier
board. If you are not using the carrier board, then you must make this connection yourself, or
use the command-line option to tell the software which serial port to use.
** During normal operation, the Stamp II takes about 7 mA. In various power-down modes, con-
sumption can be reduced to about 50 µA.

Page 8 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
Starting the Editor
With the Stamp II connected and powered, insert the BASIC Stamp
diskette and then enter the Stamp II directory by typing the following
command from the DOS prompt:
CD STAMP2
Once in the Stamp II directory, you can run the Stamp II editor/
downloader software by typing the following command:
STAMP2
The Stamp II software will start running after several seconds. The
editor screen is dark blue, with one line across the top that indicates
how to get on-screen editor help. Except for the top line, the entire
screen is available for entering and editing BASIC programs.
Command-line options:
There are several command-line options that may be useful when run-
ning the software; these options are shown below:
STAMP2 filename Runs the editor and loads filename.
STAMP2 /m Runs the editor in monochrome mode. May
give a better display on some systems, espe-
cially laptop computers.
STAMP2 /nRuns the editor and specifies which serial port
to use when downloading to the Stamp II (note
thatnmust be replaced with a serial port num-
ber of 1-4).
Normally, the software finds the Stamp II by looking on all serial ports
for a connection between DSR and RTS (this connection is made on the
carrier board). If the DSR-RTS connection is not present, then you must
tell the software which port to use, as shown above.

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 9
BASIC Stamp II
Entering & Editing Programs
We’ve tried to make the editor as intuitive as possible: to move up,
press the up arrow; to highlight one character to the right, press shift-
right arrow; etc.
Most functions of the editor are easy to use. Using single keystrokes,
you can perform the following common functions:
• Load, save, and run programs.
•Move the cursor in increments of one character, one word, one
line, one screen, or to the beginning or end of a file.
•Highlight text in blocks of one character, one word, one line, one
screen, or to the beginning or end of a file.
•Cut, copy, and paste highlighted text.
•Search for and/or replace text.
• See how the Stamp IIs memory is being used by your program.
• Identify the version of the BASIC interpreter in your Stamp II.
Editor Function Keys
The following list shows the keys that are used to perform various
functions:
F1 Display editor help screen.
Alt-R Run program in Stamp II(download the program
on the screen, then run it)
Alt-L Load program from disk
Alt-S Save program on disk
Alt-M Show memory usage maps
Alt-I Show version number of BASIC interpreter
Alt-Q Quit editor and return to DOS
Enter Enter information and move down one line
Tab Same as Enter

Page 10 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
Left arrow Move left one character
Right arrow Move right one character
Up arrow Move up one line
Down arrow Move down one line
Ctrl-Left Move left to next word
Ctrl-Right Move right to next word
Home Move to beginning of line
End Move to end of line
Page Up Move up one screen
Page Down Move down one screen
Ctrl-Page Up Move to beginning of file
Ctrl-Page Down Move to end of file
Shift-Left Highlight one character to the left
Shift-Right Highlight one character to the right
Shift-Up Highlight one line up
Shift-Down Highlight one line down
Shift-Ctrl-Left Highlight one word to the left
Shift-Ctrl-Right Highlight one word to the right
Shift-Home Highlight to beginning of line
Shift-End Highlight to end of line
Shift-Page Up Highlight one screen up
Shift-Page Down Highlight one screen down
Shift-Ctrl-Page Up Highlight to beginning of file
Shift-Ctrl-Page Down Highlight to end of file
Shift-Insert Highlight word at cursor
ESC Cancel highlighted text
Backspace Delete one character to the left
Delete Delete character at cursor
Shift-Backspace Delete from left character to beginning of line
Shift-Delete Delete to end of line
Ctrl-Backspace Delete line
Alt-X Cut marked text and place in clipboard
Alt-C Copy marked text to clipboard
Alt-V Paste (insert) clipboard text at cursor
Alt-F Find string (establish search information)
Alt-N Find next occurrence of string

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 11
BASIC Stamp II
BRANCHING
IF...THEN Compare and conditionally branch.
BRANCH Branch to address specified by offset.
GOTO Branch to address.
GOSUB Branch to subroutine at address. GOSUBs may be
nested up to four levels deep, and you may have
up to 255 GOSUBs in your program.
RETURN Return from subroutine.
LOOPING
FOR...NEXT Establish a FOR-NEXT loop.
NUMERICS
LOOKUP Lookup data specified by offset and store in vari-
able. This instruction provides a means to make a
lookup table.
LOOKDOWN Find target’s match number (0-N) and store in
variable.
RANDOM Generate a pseudo-random number.
DIGITAL I/O
INPUT Make pin an input
OUTPUT Make pin an output.
REVERSE If pin is an output, make it an input. If pin is an
input, make it an output.
LOW Make pin output low.
HIGH Make pin output high.
TOGGLE Make pin an output and toggle state.
PULSIN Measure an input pulse (resolution of 2 µs).
The following list is a summary of the BASIC instructions used by the
BASIC Stamp II. Later in this pamphlet, you’ll find complete descrip-
tions of each instruction.
◆This symbol indicates new or greatly improved instructions (compared to
the BASIC Stamp I).

Page 12 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
PULSOUT Output a timed pulse by inverting a pin for some
time (resolution of 2 µs).
BUTTON Debounce button, perform auto-repeat, and branch
to address if button is in target state.
◆SHIFTIN Shift bits in from parallel-to-serial shift register.
◆SHIFTOUT Shift bits out to serial-to-parallel shift register.
◆COUNT Count cycles on a pin for a given amount of time
(0 - 125 kHz, assuming a 50/50 duty cycle).
◆XOUT Generate X-10 powerline control codes. For use
with TW523 or TW513 powerline interface module.
SERIAL I/O
◆SERIN Serial input with optional qualifiers, time-out, and
flow control. If qualifiers are given, then the in-
struction will wait until they are received before
filling variables or continuing to the next instruc-
tion. If a time-out value is given, then the instruc-
tion will abort after receiving nothing for a given
amount of time. Baud rates of 300 - 50,000 are
possible (0 - 19,200 with flow control). Data re-
ceived must be N81 (no parity, 8 data bits, 1 stop
bit) or E71 (even parity, 7 data bits, 1 stop bit).
◆SEROUT Send data serially with optional byte pacing and
flow control. If a pace value is given, then the
instruction will insert a specified delay between
each byte sent (pacing is not available with flow
control). Baud rates of 300 - 50,000 are possible (0
- 19,200 with flow control). Data is sent as N81 (no
parity, 8 data bits, 1 stop bit) or E71 (even parity, 7
data bits, 1 stop bit).
ANALOG I/O
PWM Output PWM, then return pin to input. This can be
used to output analog voltages (0-5V) using a
capacitor and resistor.
◆RCTIME Measure an RC charge/discharge time. Can be
used to measure potentiometers.

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 13
BASIC Stamp II
SOUND
◆FREQOUT Generate one or two sinewaves of specified fre-
quencies (each from 0 - 32767 hz.).
◆DTMFOUT Generate DTMF telephone tones.
EEPROM ACCESS
◆DATA Store data in EEPROM before downloading BASIC
program.
READ Read EEPROM byte into variable.
WRITE Write byte into EEPROM.
TIME
PAUSE Pause execution for 0–65535 milliseconds.
POWER CONTROL
NAP Nap for a short period. Power consumption is
reduced.
SLEEP Sleep for 1-65535 seconds. Power consumption is
reduced to approximately 50 µA.
END Sleep until the power cycles or the PC connects.
Power consumption is reduced to approximately
50 µA.
PROGRAM DEBUGGING
DEBUG Send variables to PC for viewing.

Page 14 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
Program and Data Memory
The BS2 has 2K bytes of EEPROM which holds the executable BASIC
program and any data. Memory not used by the BASIC program can
be read and written at run-time as a data bank, or initialized with data
at download time. This memory is only affected by downloading or
run-time modification.
There are 32 bytes of RAM which serve as variable space and I/O pin
interface for the BASIC program. This memory can be accessed as
words, bytes, nibbles, or bits. Each time the BASIC program is run
anew, this memory is cleared to all zeroes.
So, the 2K byte EEPROM is for program and data, and only affected by
initial downloading or run-time modification. It survives power-down.
The 32 bytes of RAM are for run-time variables and I/O pin access.
This memory is cleared each time the BS2 is powered up, reset, or down-
loaded to.
The 2K-byte EEPROM is arranged as follows:
byte $000 Data start
Data end
Program end
byte $7FF Program start

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 15
BASIC Stamp II
The 32-byte RAM is arranged as follows:
Word Bits Description R/W
$0 0000 0000 0000 0000 Pin input states read-only
$1 0000 0000 0000 0000 Pin output latches read/write
$2 0000 0000 0000 0000 Pin directions read/write
$3 0000 0000 0000 0000 variable space read/write
$4 0000 0000 0000 0000 variable space read/write
$5 0000 0000 0000 0000 variable space read/write
$6 0000 0000 0000 0000 variable space read/write
$7 0000 0000 0000 0000 variable space read/write
$8 0000 0000 0000 0000 variable space read/write
$9 0000 0000 0000 0000 variable space read/write
$A 0000 0000 0000 0000 variable space read/write
$B 0000 0000 0000 0000 variable space read/write
$C 0000 0000 0000 0000 variable space read/write
$D 0000 0000 0000 0000 variable space read/write
$E 0000 0000 0000 0000 variable space read/write
$F 0000 0000 0000 0000 variable space read/write
Word $0 always reflects the read-state of all 16 I/O pins. Whether a pin
is an input or output, it’s logical state can be read in this word. Word
$0 is accessed by the following symbolic names:
INS the entire 16-bit word
INL the low byte of INS
INH the high byte of INS
INA the low nibble of INL
INB the high nibble of INL
INC the low nibble of INH
IND the high nibble of INH
IN0 the low bit of INS (corresponds to I/O pin P0)
IN15 the high bit of INS (corresponds to I/O pin P15)

Page 16 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
Word $1 contains the output latches for all 16 I/O pins. If a pin is in
input mode, this data is unused; but, when a pin is in output mode, its
corresponding word $1 bit sets its state. The bits are all readable and
writable, regardless of pin direction. These are its symbolic names:
OUTS the entire 16-bit word
OUTL the low byte of OUTS
OUTH the high byte of OUTS
OUTA the low nibble of OUTL
OUTB the high nibble of OUTL
OUTC the low nibble of OUTH
OUTD the high nibble of OUTH
OUT0 the low bit of OUTS - corresponds to pin P0
OUT15 the high bit of OUTS - corresponds to pin p15
Word $2 contains the direction bits for all 16 I/O pins. To place a pin in
input mode, its corresponding word $2 bit must be cleared to 0. To
place a pin into output mode, its corresponding word $2 bit must be
set to 1, at which time its word $1 bit will determine whether it drives
high or low. Word $2 has these symbolic names:
DIRS the entire 16-bit word
DIRL the low byte of DIRS
DIRH the high byte of DIRS
DIRA the low nibble of DIRL
DIRB the high nibble of DIRL
DIRC the low nibble of DIRH
DIRD the high nibble of DIRH
DIR0 the low bit of DIRS - corresponds to pin P0
DIR15 the high bit of DIRS - corresponds to pin p15

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 17
BASIC Stamp II
Words $3-$F are for general purpose variable use and have no pre-
assigned symbolic names. The VAR statement is used to allocate this
memory.
The above text introduced the physical pin-out of the BASIC Stamp II,
as well as the internal EEPROM, RAM, and I/O structure. The follow-
ing text discusses the programming of the BS2.
Programming the BASIC Stamp II
In the BASIC Stamp II, there are two general categories of BASIC state-
ments: compile-time and run-time.
Compile-time statements are resolved when you compile the
program (Alt-R or Alt-M), and they do not generate any executable
code.
Run-time statements generate code and are executed at run-time.
There are three compile-time statements. They are used for declaring
variables, constants, and data. They are:
VAR, CON, and DATA
The VAR statment - defining variables
Your program should begin with a declaration of all of its variables.
VAR statements assign symbolic names to variable RAM (RAM not
used by I/O - words $3-$F). This is done as follows:
‘Declare the variables
cat var nib ‘make “cat” a nibble variable
mouse var bit ‘make “mouse” a bit variable
dog var byte ‘make “dog” a byte variable
rhino var word ‘make “rhino” a word variable
snake var bit(10) ‘make “snake” a 10-piece bit variable

Page 18 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
The compiler will group all words, bytes, nibs, and bits, and respec-
tively arrange them into unused RAM. By pressing Alt-M, you can see
a picture of the RAM allocation. First, the three I/O words are shown,
then all words, bytes, nibs, and finally, bits, are seen. Empty RAM
follows. Alt-M is a quick way to assess how much RAM you’ve used.
The VAR usage options are as follows:
‘define unique variables
sym1 VAR bit ‘make a bit variable
sym2 VAR nib ‘make a nibble variable
sym3 VAR byte ‘make a byte variable
sym4 VAR word ‘make a word variable
‘After bit/nib/byte/word a value may be placed
‘within parentheses to declare an array size:
sym5 VAR nib (10) ‘make a 10 nibble array
‘define variables-within-variables or alias variables
sym6 VAR sym4.highbit ‘make a bit variable of sym4’s highbit
sym7 VAR sym4.lowbit ‘make a bit variable of sym4’s lowbit
sym8 VAR sym2 ‘make an alternate name for sym2
‘When using VAR to assign non-unique variables (a variable
‘name is used in lieu of bit/nib/byte/word(size)), a period may
‘be placed after the variable name and followed by modifiers.
‘Modifiers are used to identify sub-pieces of the initially-
‘mentioned variable.
sym9 VAR sym4.highbyte.lownib.bit2 ‘picky, picky...
Here are all the variable modifiers:
LOWBYTE ‘low byte of a word
HIGHBYTE ‘high byte of a word
BYTE0 ‘byte0 (low byte) of a word
BYTE1 ‘byte1 (high byte) of a word

BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone] • Page 19
BASIC Stamp II
LOWNIB ‘low nibble of a word or byte
HIGHNIB ‘high nibble of a word or byte
NIB0 ‘nib0 of a word or byte
NIB1 ‘nib1 of a word or byte
NIB2 ‘nib2 of a word
NIB3 ‘nib3 of a word
LOWBIT ‘low bit of a word, byte, or nibble
HIGHBIT ‘high bit of a word, byte, or nibble
BIT0 ‘bit0 of a word, byte, or nibble
BIT1 ‘bit1 of a word, byte, or nibble
BIT2 ‘bit2 of a word, byte, or nibble
BIT3 ‘bit3 of a word, byte, or nibble
BIT4 ‘bit4 of a word or byte
BIT5 ‘bit5 of a word or byte
BIT6 ‘bit6 of a word or byte
BIT7 ‘bit7 of a word or byte
BIT8 ‘bit8 of a word
BIT9 ‘bit9 of a word
BIT10 ‘bit10 of a word
BIT11 ‘bit11 of a word
BIT12 ‘bit12 of a word
BIT13 ‘bit13 of a word
BIT14 ‘bit14 of a word
BIT15 ‘bit15 of a word
In summary, to declare variables, VAR statements are used. VAR
statements either declare unique variables or variables-within-variables
and alias-variables.
For defining unique variables:
symbol VAR size (array)
- symbol is a unique name for a variable
- size is either WORD, BYTE, NIB, or BIT
- (array) is an optional expression which declares an array size
For defining variables-within-variables or alias-variables:

Page 20 • BASIC Stamp II Manual 0.94 • Parallax, Inc. • [phone]
BASIC Stamp II
symbol VAR variable.modifiers
- symbol is a unique name for a variable
- variable is a defined variable name
- .modifiers are optional and used to define variables-within-variables
The compiler will group all declarations by size (in the case of unique
variables) and assign them to unused RAM. Alt-M lets you see the
result of this process. Non-unique variables are in-whole or in-part
derived from unique variables and get assigned within the unique-
variable memory.
Keep in mind that you may make alias names for the pin variables:
keyin var in5 ‘make “keyin” a way to read P5’s state.
Note for Stamp I users: W0-W12 (and the corresponding B0-B25) are pre-
defined by the compiler software to make use of Stamp I programs easier. If
you use a Stamp I program with the Stamp II, you can enter the older “Wx”
and “Bx” variable names without having to define them first.
The CON statment - defining constants
The CON statement is similar to the VAR statement, except that it is
for defining constant values and assigning them to symbolic names.
This is handy for having a single declaration which gets accessed
throughout your program. The CON syntax is as follows:
symbol CON expression ‘assign expression to “symbol”
- symbol is a unique symbolic name for a constant
- expression is a compile-time-resolvable constant
level CON 10 ‘“level” is same as 10 in program
limit CON 10*4<<2 ‘“limit” is 160
expressions after CON can contain the following binary operators and
are resolved left-to-right: