See Practical serial communication

BASIC Stamp

A variety of products from Parallax. We use the BS2-IC (we have 5), we also have one SX.

• Javelin Stamp, works in a subset of Java and can run multiple threads. Almost like Phidgets.
• colour-coded
• indicated in the manual for features not available to all stamps
  • BS1 is a SIP (single row of pins), all the rest are DIP (two rows)

Pin layout

Pins 1-4: (serial) programming ATN=attention Pins 5-20: data Pin 21: stable 5V (CMOS VDD), output if there is something on pin 24, otherwise input Pin 22: connect ground for reset Pin 23, 4: Ground (CMOS VSS) Pin 24: input voltage, will be converted to 5V by the Stamp on pin 21

Stamp major components

See Module Schematic

• Voltage regulator
• PBASIC interpreter + PIC microcontroller (custom-made for Prallax)
  • 32 Byte RAM
• Clock oscillator
• EEPROM 2 kiloByte memory

The programming cable

• Works well even without the capacitors
• DTR connceted directly to stamp pin 3, no capacitor on it
• No capacitor between pin 3 and 4

DSR and RTS are connected for automatic port detection. The Stamp software will scan the serial ports and look for such connectors.

PBASIC

Download BASIC Stamp Editor

Variable types

• Bit
• Nib
• Byte
• Word

Array of the above

• bla VAR Bit(3)

Modifiers

• parts of a certain variable visible as other variables
• bla_high VAR bla.HIGHBYTE
• bla_low VAR bla.LOWBYTE
• also low nibble, high nibble, nibble 0-3 of a word, bit 0-7 of a byte, bit 0-15 of a word, see table 4.3

Accessing the RAM as predefined values

• INS (Word), INH, INL (Byte), INA, INB, INC, IND (Nib), IN0...IN15 (Bit)
  • useful for digital input
  • though you can use PIN definitions instead so you can change the circuit easily
• same for OUT, DIR (1 Word each)
• besides that, W0-W12, B0-B25 (13 Words)
• 1+1+1+13= 16 Words= 32 Bytes of RAM
• see Memory Map, Ctrl-M

Literals

% binary

$ hexadecimal

Operators and Math

• + - * / << >> & | ^
• a subset of C operators
• ~ bit complement
• a wide range of functions (ABS, SQR, MIN, MAX, trigonometrical)

Digital output

• see program above

Digital input

• simply use IN1, IN2...
• or name a PIN
• BS2 source

Analog input

• RCTIME
• BS2 source

Driving a servo

• red to 5V, yellow to Stamp pin, black to ground
• BS2 source

Categories of PBASIC statements

• see the manual, page 124