PBASIC is a microcontroller-based version of BASIC created by Parallax, Inc. in 1992. PBASIC was created to bring ease of use to the microcontroller and embedded processor world. It is used for writing code for the BASIC Stamp microcontrollers. After the code is written, it is tokenized and loaded into an EEPROM on the microcontroller. These tokens are fetched by the microcontroller and used to generate instructions for the processor. Syntax When starting a PBASIC file, the programmer defines the version of the BASIC Stamp and the version of PBASIC that will be used. Variables and constants are usually declared first thing in a program. The DO LOOP, FOR NEXT loop, IF and ENDIF, and some standard BASIC commands are part of the language, but many commands like PULSOUT, HIGH, LOW, DEBUG, and FREQOUT are native to PBASIC and are used for special purposes that are not available in traditional BASIC (such as having the Basic Stamp ring a piezoelectric speaker, for example). Programming In the Stamp Editor, the PBASIC integrated development environment (IDE) running on a (Windows) PC, the programmer has to select 1 of 7 different basic stamps, BS1, BS2, BS2E, BS2SX, BS2P, BS2PE, and BS2PX, which is done by using one of these commands: ' {$STAMP BS1} ' {$STAMP BS2} ' {$STAMP BS2e} ' {$STAMP BS2sx} ' {$STAMP BS2p} ' {$STAMP BS2pe} ' {$STAMP BS2px} The programmer must also select which PBASIC version to use, which he or she may express with commands such as these: ' {$PBASIC 1.0} ' use version 1.0 syntax (BS1 only) ' {$PBASIC 2.0} ' use version 2.0 syntax ' {$PBASIC 2.5} ' use version 2.5 syntax An example of a program using HIGH and LOW to make an LED blink, along with a DO...LOOP would be: DO HIGH 1 'turn LED on I/O pin 1 on PAUSE 1000 'keep it on for 1 second LOW 1 'turn it off PAUSE 500 'keep it off for 500 msec LOOP 'repeat forever An example of a program using HIGH and LOW along with the FOR NEXT loop would be: counter VAR Byte 'sets variable "counter FOR counter = 1 to 5 HIGH 1 'make pin 1 logic level high (5 V) PAUSE 1000 'keep it on for 1000 msec LOW 1 'turn it off PAUSE 500 'keep it off for 500 msec NEXT 'redirects to beginning four more times END 'end program Comments