TMS320VC5416
Fixed-Point Digital Signal Processor
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SPRS095O–MARCH 1999–REVISED JANUARY 2005
3.7.1 Enhanced 8-/16-Bit Host-Port Interface (HPI8/16)
The host-port interface, also referred to as the HPI8/16, is an enhanced version of the standard 8-bit HPI
found on earlier TMS320C54x™ DSPs (542, 545, 548, and 549). The HPI can be used to interface to an
8-bit or 16-bit host. When the address and data buses for external I/O is not used (to interface to external
devices in program/data/IO spaces), the HPI can be configured as an HPI16 to interface to a 16-bit host.
This configuration can be accomplished by connecting the HPI16 pin to logic "1”.
When the HPI16 pin is connected to a logic ,,0”, the HPI is configured as an HPI8. The HPI8 is an 8-bit
parallel port for interprocessor communication. The features of the HPI8 include:
Standard features:
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•
•
Sequential transfers (with autoincrement) or random-access transfers
Host interrupt and C54x™ interrupt capability
Multiple data strobes and control pins for interface flexibility
The HPI8 interface consists of an 8-bit bidirectional data bus and various control signals. Sixteen-bit
transfers are accomplished in two parts with the HBIL input designating high or low byte. The host
communicates with the HPI8 through three dedicated registers — the HPI address register (HPIA), the
HPI data register (HPID), and the HPI control register (HPIC). The HPIA and HPID registers are only
accessible by the host, and the HPIC register is accessible by both the host and the device.
Enhanced features:
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•
Access to entire on-chip RAM through DMA bus
Capability to continue transferring during emulation stop
The HPI16 is an enhanced 16-bit version of the TMS320C54x™ DSP 8-bit host-port interface (HPI8). The
HPI16 is designed to allow a 16-bit host to access the DSP on-chip memory, with the host acting as the
master of the interface. Some of the features of the HPI16 include:
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•
•
•
16-bit bidirectional data bus
Multiple data strobes and control signals to allow glueless interfacing to a variety of hosts
Only nonmultiplexed address/data modes are supported
18-bit address bus used in nonmultiplexed mode to allow access to all internal memory (including
internal extended address pages)
•
•
HRDY signal to hold off host accesses due to DMA latency
The HPI16 acts as a slave to a 16-bit host processor and allows access to the on-chip memory of the
DSP.
NOTE
Only the nonmultiplexed mode is supported when the HPI is configured as a HPI16.
The HPI functions as a slave and enables the host processor to access the on-chip memory. A major
enhancement to the HPI over previous versions is that it allows host access to the entire on-chip memory
range of the DSP. The host and the DSP both have access to the on-chip RAM at all times and host
accesses are always synchronized to the DSP clock. If the host and the DSP contend for access to the
same location, the host has priority, and the DSP waits for one cycle. Note that since host accesses are
always synchronized to the device clock, an active input clock (CLKIN) is required for HPI accesses during
IDLE states, and host accesses are not allowed while the device reset pin is asserted.
Functional Overview
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