NS32FX161-15 Datasheet, PDF (72/102 Pages) National Semiconductor (TI) – Advanced Imaging/Communication Signal Processors

4 0 Device Specifications (Continued)
BPU
BPU Cycle
This signal is activated during a bus cycle to en-
able an external BITBLT processing unit The
EXTBLT instruction activates this signal
Note BPU is low (Active) only during bus cycles involving pre-
fetching instructions and execution of EXTBLT oper-
ands It is recommended that BPU ADS and status lines
(ST0–ST3) be used to qualify BPU bus cycles If a DMA
circuit exists in the system the HLDA signal should be
used to further qualify BPU cycles BPU may become
active during T4 of a non-BPU bus cycle and may be-
come inactive during T4 of a BPU bus cycle BPU must
be qualified by ADS and status lines (ST0–ST3) to be
used as an external gating signal
RSTO Reset Output
This signal becomes active when RSTI is low
initiating a system reset
RD
Read Strobe
Activated during CPU or DMA read cycles to en-
able reading of data from memory or peripherals
See Section 3 5 5 2
WR
Write Strobe
Activated during CPU or DMA write cycles to en-
able writing of data to memory or peripherals
TSO
Timing State Output
The falling edge of TSO identifies the beginning
of state T2 of a bus cycle The rising edge identi-
fies the beginning of state T4
DBE
Data Buffers Enable
Used to control external data buffers It is active
when the data buffers are to be enabled
OSCOUT Crystal Output
This line is used as the return path for the crystal
(if used) When an external clock source is used
OSCOUT should be left unconnected or loaded
with no more than 5 pF of stray capacitance
IAS
Special Cycle Address Strobe
Signals the beginning of a special bus cycle
CTTL1 – 2 System Clock
Output clock for bus timing CTTL1 and CTTL2
must be externally connected together
FCLK Fast Clock
This clock is derived from the clock waveform on
OSCIN Its frequency is either the same as
OSCIN or is lower depending upon the scale fac-
tor programmed into the CFG register
ALE
Address Latch Enable
Active high signal that can be used to control
external address latches
IOUT Interrupt Output
Activated when the execution of a command list
stops and the associated interrupt is enabled
4 1 4 Input-Output Signals
AD0 –15 Address Data Bus
Multiplexed Address Data Information Bit 0 is
the least significant bit of each
SPC
Slave Processor Control
Used by the CPU as the data strobe output for
slave processor transfers used by a slave proc-
essor to acknowledge completion of a slave in-
struction See Section 3 5 5 7
DDIN
Data Direction
Status signal indicating the directon of the data
transfer during a bus cycle During HOLD ac-
knowledge this signal becomes an input and de-
termines the activation of RD or WR
ADS
Address Strobe
Controls address latches signals the beginning
of a bus cycle During HOLD acknowledge this
signal becomes an input and the CPU monitors it
to detect the beginning of a DMA cycle and gen-
erate the relevant strobe signals When a DMA is
used ADS should be pulled up to V_CC through a
10 kX resistor
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