Output Dma Activation; Decimation By 2 - Motorola DSP56305 User Manual

12.5.3

Output DMA Activation

The DMA for output data transfers should be programmed for single word transfers
triggered by the FDOBF bit. The DMA can be activated at any time (even before the
FCOP is enabled).
12.5.4

Decimation by 2

FIR decimation by 2 is performed on input, when the FDCM bit is set. When FCOP
decimates input, it waits until it gets two input data items (depending on the mode, the
data may be real or complex) in FDM and then performs the FIR calculation on the
second input data items only. This is equivalent to performing the full FIR filter but
reading only every second FIR result, thus saving half the calculations.
MOTOROLA DSP56305 User's Manual
Filter Co-Processor
Operation Modes
12-16