Datasheet

Jon Waddington
13
3.1 The Parallax Propeller
The Parallax Propeller is a powerful chip capable of high speed processing (up to 80MHz).
The chip has eight processors, called cogs, which can perform independently or
cooperatively, as the program dictates. This eliminates the need for interrupts as a cog
can be dedicated to a single task, leaving the main program to continue undisturbed
[21].
A Propeller application contains code written in the chip’s high level SPIN language and,
optionally, some Propeller Assembly (PASM) language. The SPIN code is interpreted at
run time by the chips SPIN interpreter and the PASM is run directly by a cog [21].
A Propeller application contains one or more SPIN files, called objects. Each object can
contain up to six different types of blocks which are shown in the table below [21].
The Propeller has a memory of 64KB. This consists of 32KB of RAM and 32KB of ROM.
The ROM contains the Boot Loader, SPIN Interpreter, math functions and the font ROM.
The RAM is used for the Propeller application, meaning an external EEPROM must be
used to store the program after the Propeller has been switched off. The Boot Loader is
responsible for loading the program into the RAM from the EEPROM [21].
Block
Purpose
CON
The Constant block which defines the constants
VAR
The Variable block defines the global variables
OBJ
The Object block defines the referenced objects
PUB
The Public blocks contain SPIN code
PRI
The Private blocks contain SPIN code
DAT
The Data block contains PASM