The Motorola DSP56002 is a high performance 24 Bit DSP (Digital Signal Processor). This refers to the device utilizing a 24 Bit Data Bus to exchange information. In this case, it is external. By comparison, most current DSP’s in the same class: Namely those that perform Fixed Point Numerical calculations, have either a 16 Bit external Data Bus or none at all (only able to address internal memory). The DSP56002 can address 64K of external memory, and 512 Bytes of internal RAM. This is admittedly not mind blowing, however is more than sufficient for most applications. Even Texas Instruments current range of Piccolo DSC’s (Digital Signal Controllers) have the same constraints with internal FLASH.

The DSP56002 runs at a very respectable speed of 66 MIPs (Million Instructions Per Second). Up to 198 MOPs (Million Operations Per Second) at 66 MHz can be achieved due to its inherent Harvard Architecture, which permits simultaneous access to program memory and two data memories. A double precision 48 by 48 Bit multiplication with a 96 Bit result can be calculated in 6 instruction cycles. A 56 Bit Addition or Subtraction can be completed in only 1 Instruction cycle. These Math properties make it ideal for real time Probability, FFT, and Neural Network applications.

For the Electronic Design Engineer interested in Stereo Audio Applications, or IQ demodulation schemes the DSP56002 features an SSI (Synchronous Serial Interface) which makes for a simple interface to Audio CODEC’s. When the DSP is used as a Slave processor (common to most applications) a built in Host Interface and ONCE port provides a convenient interface for communications. Just as important, this DSP is available in 132 and 144 pin QFP (Quad Flat Pack) packages. This makes it easy to implement prototypes as part of a Hardware development phase. The part also has up to 25 General Purpose I/O pins and a 24 Bit Timer/Event Counter that can be used for Waveform generation or simply to measure the time between Waveform changes.

Unfortunately, Motorola SPS changed their name to Freescale Semiconductor back in 2004 and ended up bowing to Texas Instruments dominance in the DSP marketplace. The organization moved away from DSP development, and the DSP56002 became an obsolete part. However, these processors are still available in limited quantities from major Electronic Component Resellers. Contrary to the popular belief: Obsolete means ‘not recommended for new designs’, the only challenge with working with the DSP56002 is sourcing parts, and even this is only a minor challenge. The DSP56002 is still an extremely Powerful DSP that can offer some unique product benefits.

Think outside of the box, and consider it for your next electronic design project!