dsp56366 Freescale Semiconductor, Inc, dsp56366 Datasheet - Page 9

• Manufacturer Part Number: dsp56366
• Description: Dsp56366 24-bit Audio Digital Signal Processor
• Manufacturer: Freescale Semiconductor, Inc

2.5.1
2.5.2
2.5.3
Freescale Semiconductor
Signal Name
RAS0–RAS2
AA0–AA2/
A0–A17
D0–D23
Signal
Name
Signal
Name
CAS
WR
RD
External Address Bus
External Data Bus
External Bus Control
Input/Output
Output
Type
Output
Output
Output
Output
Type
Type
Tri-stated
during
State during
Reset
State
Tri-stated
Tri-stated
Tri-stated
Tri-stated
Tri-stated
during
Reset
Reset
State
Table 2-5 External Address Bus Signals
Table 2-7 External Bus Control Signals
Table 2-6 External Data Bus Signals
Address Bus—When the DSP is the bus master, A0–A17 are active-high outputs
that specify the address for external program and data memory accesses.
Otherwise, the signals are tri-stated. To minimize power dissipation, A0–A17 do not
change state when external memory spaces are not being accessed.
DSP56366 Technical Data, Rev. 3.1
Data Bus—When the DSP is the bus master, D0–D23 are active-high,
bidirectional input/outputs that provide the bidirectional data bus for external
program and data memory accesses. Otherwise, D0–D23 are tri-stated.
Address Attribute or Row Address Strobe—When defined as AA, these
signals can be used as chip selects or additional address lines. When defined
as RAS, these signals can be used as RAS for DRAM interface. These signals
are tri-statable outputs with programmable polarity.
Column Address Strobe— When the DSP is the bus master, CAS is an
active-low output used by DRAM to strobe the column address. Otherwise, if the
bus mastership enable (BME) bit in the DRAM control register is cleared, the
signal is tri-stated.
Read Enable—When the DSP is the bus master, RD is an active-low output
that is asserted to read external memory on the data bus (D0-D23). Otherwise,
RD is tri-stated.
Write Enable—When the DSP is the bus master, WR is an active-low output
that is asserted to write external memory on the data bus (D0-D23). Otherwise,
WR is tri-stated.
Signal Description
Signal Description
Signal Description
2-5