In a change to our regular column, AND have invited key individuals from the electronics industry to showcase their current Micro's of the Month. This month, we're very pleased to feature the Parallax P8X32A Propeller by David Whale, Director at Thinking Binaries Ltd.

A high performance microcontroller, with a novel architecture that challenges some traditional design trends - The P8X32A Propeller MCU from Parallax Inc., is aimed at embedded systems requiring high speed processing, while maintaining low current consumption & a small physical footprint. Building on the success of the Parallax BASIC STAMP & an 8 year development programme, the Propeller is a serious contender for small to medium scale high-speed embedded applications.

The Propeller has 8 identical 32-bit CPU cores onboard, called "cogs". A cog is a 32-bit RISC processor with its own 2K of local RAM, well designed instruction set, & 2 fast local timer peripherals. Each cog has access to a shared 64K memory map - 32K of which is RAM - & 32 GPIO pins. There is no flash memory on the device, programs instead are loaded in their entirety into shared RAM via a host serial interface (e.g. from a PC or another host processor), or via an I2C interface such as from an external serial EEPROM. Typically, multi processor solutions with shared resources will require some arbitration scheme to access these resources, & their design can be quite complex & introduce unpredictability in real-time code. The Propeller takes a much simpler design approach through its central HUB. The Hub allocates timeslots to each cog on a round-robin basis.

Each Cog has its own set of highly programmable fast timers, & a configuration of these timers that can be used to generate PAL, NTSC & broadcast video complete with audio sub carrier modulation. The on-board ROM has a full 256 character bitmap table, & the combination of the two can generate good quality TV/VGA displays requiring one or two of the cog's only.

The performance story doesn't stop there. Each cog can run from DC up to 80MHz, & there are 8 of them. With 4 cycles per instruction, this gives 160MIPS of performance. Each cog can be allocated dynamically its own code to load from main RAM into its local RAM, meaning that code mostly runs without any hub synchronisation delays. However, most importantly, When one looks deeper at the architecture, there are a few things that will surprise you by their absence, such as any form of interrupt handling, & apart from the onboard timers, an absence of the plethora of peripheral hardware found on many other MCU's targeted at the embedded market - & this is the challenge to traditional thinking.

Want to learn more? Then be sure to read the supplementing article 'Parallax P8X32A Propeller - why the novel architecture?' taking a closer look inside the Propeller architecture. Alternatively, for more information please visit Parallax [www.parallax.com]

Useful links
Parallax Inc [www.parallax.com]
Thinking Binaries Ltd [www.thinkingbinaries.com]