Parallel Port - Analog Devices ADSP-21261 SHARC Hardware Reference Manual

8 PARALLEL PORT

The ADSP-2126x processor has a parallel port that allows bidirectional
transfers between it and external parallel devices. Using the parallel port
bus and control lines, the processor can interface to 8-bit or 16-bit wide
external memory devices. The parallel port provides a DMA interface
between internal and external memory and has the ability to support core
driven data transfer modes. Regardless of whether 8-bit or 16-bit external
memory devices are used, the internal data word size is always 32 bits
(normal word addressing), and the parallel port employs packing to place
the data appropriately.
This chapter describes the parallel port operation, registers, interrupt
function, and transfer protocol.
parallel port.
The processor provides two data packing modes, 8/32 and 16/32. For
reads, data packing involves shifting multiple successive 8- or 16-bit ele-
ments from the parallel port to the ADSP-2126x's Receive register to form
each 32-bit word, transferring multiple successive 8-bit or 16-bit ele-
ments. For writes, packing involves shifting each 32-bit word out into 8-
or 16-bit elements that are placed into the memory device.
ADSP-2126x SHARC Processor Hardware Reference
Figure 8-1 shows a block diagram of the
8-1