Altera Avalon Tri-State Conduit Components User Manual
Page 9
Chapter 2: Generic Tri-State Controller
2–3
Parameters
May 2011
Altera Corporation
Avalon Tri-State Conduit Components User Guide
Preliminary
Table 2–2
lists parameters that you can use to define the signal timing of an external
memory. The appropriate values for these parameters are typically listed in the
vendor’s data sheet for the memory device.
byteenable
On/Off
Enables or disables the
byteenable
signal, which enables specific byte lanes
during transfers on ports with widths greater than 8 bits. Each bit in the
byteenable
signal corresponds to a byte in
writedata
and
readdata
. Bit <n>
of
byteenable
indicates whether byte <n> is being written to. During writes, the
byteenable
signal specifies which bytes are being written to; other bytes
should be ignored by the external device. During reads, the
byteenable
signal
indicates which bytes the Generic Tri-State Controller is reading.
chipselect
On/Off
Enables or disables the
chipselect
signal, which is always used in conjunction
with the
read
or write
signal
.
lock
On/Off
Enables or disables the
lock
signal, which ensures that once a master wins
arbitration, it maintains access to the slave for multiple transactions. It is
asserted coincident with the first
read
or
write
of a locked sequence of
transactions, and is deasserted on the final transaction of a locked sequence of
transactions.
address
On/Off
Enables or disables the
address
signal, which represents a byte address
regardless of the word size of the external device.
waitrequest
On/Off
Enables or disables the
waitrequest
signal, which is asserted by the external
device when it is unable to respond to a
read
or
write
request.
writebyteenable
On/Off
Enables or disables the
writebyteenable
signal, which is equivalent to the
logical
AND
of the
byteenable
and
write
signals. When the
writebyteenable
signal is used, the
write
and
byteenable
signals are not used.
resetrequest
On/Off
Enables or disables the
resetrequest
signal, which is an input from the
off-chip device requesting a system reset.
irq
On/Off
Enables or disables the
irq
signal, which allows the external device to interrupt
the Generic Tri-state Controller.
resetoutput
On/Off
Enables or disables the a
resetoutput
signal, from the Generic Tri-state
Controller to the external device which requests that the external device be reset.
Other Parameters
embeddedsw.configuration.
isNonVolatileStorage
These are configuration names that you can use to identify your components to
downstream embedded software tools. A value of 1 identifies the parameter as
true
, a value of 0 identifies it as
false
.
For more information about these configuration names, re
chapter in the Nios II Software
Developer’s Handbook.
embeddedsw.configuration.
isPrintableDevice
embeddedsw.configuration.
isMemoryDevice
embeddedsw.configuration.
isFlash
embeddedsw.configuration.
isEthernetMacDevice
Table 2–1. Signal Selection Parameters
Parameter
Value
Description