
Clock and Control Signals
Rev. A
2-7
Copyright 2000 by LSI Logic Corporation. All rights reserved.
CPSEQ
Sequential Address
This output goes HIGH when the address of the next
memory cycle is related to that of the last memory
access. The new address is either the same as the pre-
vious one, four greater in ARM state, or two greater when
fetching opcodes in Thumb state.
O
This signal is analogous to SEQ on the hard macrocell.
CPnTRANS
Not Memory Translate
When LOW, this signal indicates that the processor is in
user mode. It can be used to indicate to memory man-
agement hardware when to bypass translation of the
addresses, or as an indicator of privileged mode activity.
O
This signal is analogous to nTRANS on the hard macro-
cell.
2.3 Clock and Control Signals
This section describes the clock, interrupt, and reset signals.
CLK
Clock Input
All ARM7TDMI Smemory accesses and internal opera-
tions are clocked with respect to CLK. All outputs change
from the rising edge of CLK, and all inputs are sampled
on the rising edge of CLK.
I
The CLKEN input can be used with a free running CLK to
add synchronous wait states. Alternatively, the clock can
be stretched indefinitely in either phase to allow access
to slow peripherals or memory, or to put the system into
a low power state.
CLK is also used for serial scan chaindebug operation
with the EmbeddedICE tool chain.
This signal is analogous to inverted MCLK on the hard
macrocell.
CLKEN
Wait State Control
When accessing slow peripherals, driving CLKEN LOW
forces the ARM7TDMI Sto wait for an integer number of
CLK cycles. When the CLKEN control is not used, it must
be tied HIGH.
I
This signal is analogous to nWAIT on the hard macrocell.