
Lattice Semiconductor
149
Data Sheet
November 2006
ORCA Series 3C and 3T FPGAs
Special-Purpose Pins
(continued)
CS0
, CS1
I
I/O
CS0
and CS1 are used in the asynchronous peripheral, slave parallel, and microprocessor
conguration modes. The FPGA is selected when CS0 is low and CS1 is high. During cong-
uration, a pull-up is enabled.
After conguration, these pins are user-programmable I/O pins (see Note).
RD
/
MPI_STRB
I
I/O
RD
is used in the asynchronous peripheral conguration mode. A low on RD changes D7 into
a status output. As a status indication, a high indicates ready, and a low indicates busy. WR
and RD should not be used simultaneously. If they are, the write strobe overrides.
This pin is also used as the microprocessor interface (MPI) data transfer strobe. For
PowerPC, it is the transfer start (TS). For i960, it is the address/data strobe (ADS).
After conguration, if the MPI is not used, this pin is a user-programmable I/O pin (see Note).
WR
I
I/O
WR
is used in the asynchronous peripheral conguration mode. When the FPGA is selected,
a low on the write strobe, WR, loads the data on D[7:0] inputs into an internal data buffer. WR
and RD should not be used simultaneously. If they are, the write strobe overrides.
After conguration, this pin is a user-programmable I/O pin (see Note).
A[17:0]
O
I/O
During master parallel conguration mode, A[17:0] address the conguration EPROM. In
microprocessor interface (MPI) mode, many of the A[n] pins have alternate uses as described
below. See the Special Function Blocks section for more MPI information. During congura-
tion, if not in master parallel or an MPI conguration mode, these pins are 3-stated with a pull-
up enabled.
After conguration, the pins are user-programmable I/O pins (see Note).
Pin Information (continued)
Table 67. Pin Descriptions (continued)
Symbol
I/O
Description
Note: The FPGA States of Operation section contains more information on how to control these signals during start-up. The timing of DONE
release is controlled by one set of bit stream options, and the timing of the simultaneous release of all other conguration pins (and the
activation of all user I/Os) is controlled by a second set of options.
Select
devices
have
been
discontinued.
See
Ordering
Information
section
for
product
status.