5

SAM2653

DSP engine

The DSP engine operates on a frame-timing basis with the frame subdivided into 64

process slots. Each process is itself divided into 16 micro-instructions known as

« algorithm ». Up to 32 DSP algorithms can be stored on-chip in the Alg RAM memory,

allowing

the

device

to

be

programmed

for

a

number

of

audio

signal

generation/processing applications.

The DSP engine is capable of generating 64 simultaneous voices using algorithms such

as wavetable synthesis with interpolation, alternate loop and 24dB resonant filtering for

each voice. Slots may be linked together (ML RAM) to allow implementation of more

complex synthesis algorithms.

A typical musical instrument application will use a little more than half the capacity of the

DSP engine for synthesis, thus providing state of the art 38 voices synthesis polyphony.

The remaining processing power may be used for typical function like reverberation,

chorus, surround effect, equalizer, etc.

Frequently accessed DSP parameter data are stored into 5 banks of on-chip RAM

memory. Sample data or delay lines, which are accessed relatively infrequently, are

stored in external ROM, or into the built-in 32kx16 RAM. The combination of localized

micro-program memory and localized parameter data allows micro-instructions to

execute in 20.3 ns (49 MIPS). Separate busses from each of the on-chip parameter

RAM memory banks allow highly parallel data movement to increase the effectiveness

of each micro-instruction. With this architecture, a single micro-instruction can

accomplish up to 6 simultaneous operations (add, multiply, load, store, etc.), providing a

potential throughput of 294 million operations per second (MOPS).

Enhanced P16 control processor and I/O functions

The Enhanced P16 control processor is the new version of P16 processor with added

instructions allowing C compiling. The P16 is a general-purpose 16-bit CISC processor

core, which runs from external memory. A debug ROM is included on-chip for easy

development of firmware directly on the target system. This ROM also contains the

necessary code to directly program externally connected flash memory. The P16

includes 256 words of local RAM data memory for use as registers, scratchpad data

and stack.

The P16 control processor writes to the parameter RAM blocks within the DSP core in

order to control the synthesis process. In a typical application, the P16 control processor

parses and interprets incoming commands from the MIDI UART or from the scanning

interface and then controls the DSP by writing into the parameter RAM banks in the

DSP core. Slowly changing synthesis functions, such as LFOs, are implemented in the

P16 control processor by periodically updating the DSP parameter RAM variables.

The P16 control processor interfaces with other peripheral devices, such as the system

control and status registers, the on-chip MIDI UART, the on-chip timers and the

scanning interface through specialized « intelligent » peripheral I/O logic. This I/O logic

automates many of the system I/O transfers to minimize the amount of overhead

processing required from the P16.