SM320VC5510A-EP Datasheet, PDF (27/82 Pages) Texas Instruments – SM320VC5510A-EP Fixed-Point Digital Signal Processor

Functional Overview
3.2.3 Enhanced Host Port Interface (EHPI)
The 5510 EHPI provides a 16-bit parallel interface to a host with the following features:
• 20-bit host address bus
• 16-bit host data bus
• Multiplexed and non-multiplexed bus modes
• Host access to on-chip SARAM, on-chip DARAM, and external memory
• 20-bit address register (in multiplexed mode) with autoincrement capability for faster transfers
• Multiple address/data strobes provide a glueless interface to a variety of hosts
• HRDY signal for handshaking with host
The 5510 EHPI can access internal DARAM, internal SARAM and a portion of the external memory space.
The EHPI cannot directly access the on-chip peripherals and cannot access the memory-mapped registers
below word address 000060h in DARAM. Note that all memory accesses made though the EHPI are
word-addressed. A map of the memory space accessible by the EHPI is shown in Figure 3−4. The EHPI can
access from word address 000060h to 0FFFFFh. The shaded areas of the memory map are not accessible
by the EHPI.
Word Address
000000h
000060h
Memory Blocks
Memory Mapped
Registers (DARAM)
DARAM
008000h
028000h
SARAM
External − CE0
Memory Accessible
Through the EHPI
100000h
200000h
External − CE0
External − CE1
400000h
600000h
External − CE2
External − CE3
NOTE A: The shaded areas of the memory map are not accessible by the EHPI.
Figure 3−4. EHPI Memory Map
When the EHPI inputs are uncontrolled, noise on the inputs can cause spurious accesses that may corrupt
internal memory. If the EHPI is not driven by a host, the HCS pin should be driven high by one of the following
methods:
• An external device
• External pullup resistor, or
• The on-chip pullup circuit controlled by the HPE bit in the System Register (SYSR). See Section 3.2.1
for more information on how to configure this control.
As of revision 2.1, the byte-enable function of the EHPI is no longer supported. Pins HBE0 and HBE1 must
be driven low at all times.
August 2003 − Revised November 2003
SGUS045A
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