SIGNAL DESCRIPTIONS
MOTOROLA
DSP56002 PIN DESCRIPTIONS
2 - 9
when the host interface is not being used. These pins are configured as GPIO input pins
during hardware reset.
2.2.5.2
Host Address (HA0–HA2)
These inputs provide the address selection for each host interface register. HA0–HA2 can
be programmed as general-purpose I/O pins (PB8–PB10) when the host interface is not
being used. These pins are configured as GPIO input pins during hardware reset.
2.2.5.3
Host Read/Write (HR/W)
This input selects the direction of data transfer for each host processor access. If HR/W
is high and HEN is asserted, H0-H7 are outputs and DSP data is transferred to the host
processor. If HR/W is low and HEN is asserted, H0-H7 are inputs and host data is trans-
ferred to the DSP. HR/W is stable when HEN is asserted. It can be programmed as a
general-purpose I/O pin (PB11) when the host interface is not being used, and is config-
ured as a GPIO input pin during hardware reset.
2.2.5.4
Host Enable (HEN)
This input enables a data transfer on the host data bus. When HEN is asserted and HR/W
is high, H0–H7 become outputs and the host processor may read DSP56002 data. When
HEN is asserted and HR/W is low, H0–H7 become inputs. When HEN is deasserted, host
data is latched inside the DSP. Normally, a chip select signal derived from host address
decoding and an enable clock are used to generate HEN. HEN can be programmed as a
general-purpose I/O pin (PB12) when the host interface is not being used, and is config-
ured as a GPIO input pin during hardware reset.
2.2.5.5
Host Request (HREQ)
This open-drain output signal is used by the host interface to request service from the
host processor, DMA controller, or a simple external controller. HREQ can be pro-
grammed as a general-purpose I/O (not open-drain) pin (PB13) when the host
interface is not being used.
2.2.5.6
Host Acknowledge (HACK)
This input has two functions. It provides a host acknowledge handshake signal for DMA
transfers and it receives a host interrupt acknowledge compatible with MC68000 Family
processors. When the port is defined as the host interface and neither of the HACK pin’s
two functions are being used, the user may program this input as a general-purpose I/O pin.
For more details about the programming options for this pin, see
Host Ac-
knowledge (HACK)
. This pin is configured as a GPIO input pin during hardware reset.
Note:
HACK should always be pulled high when it is not in use.
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For More Information On This Product,
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