Data Sheet
June 1999
ORCA Series 2 FPGAs
FPGA States of Operation (continued)
VDD
RESET
PRGM
INIT
M[3:0]
CCLK
HDC
LDC
DONE
USER I/O
INTERNAL
RESET
(gsm)
INITIALIZATION
CONFIGURATION
START-UP
OPERATION
5-4482(F)
Figure 37. Initialization/Configuration/Start-Up Waveforms
All OR2CxxA I/Os operate as TTL inputs during config-
Configuration
uration (OR2TxxA/OR2TxxB I/Os are CMOS-only). All
I/Os that are not used during the configuration process
are 3-stated with internal pull-ups. During configura-
tion, the PLC latch/FFs are held set/reset and the inter-
nal BIDI buffers are 3-stated. The TRIDIs in the PICs
are not 3-stated. The combinatorial logic begins to
function as the FPGA is configured. Figure 37 shows
the general waveform of the initialization, configuration,
and start-up states.
The ORCA Series FPGA functionality is determined by
the state of internal configuration RAM. This configura-
tion RAM can be loaded in a number of different
modes. In these configuration modes, the FPGA can
act as a master or a slave of other devices in the sys-
tem. The decision as to which configuration mode to
use is a system design issue. The next section dis-
cusses configuration in detail, including the configura-
tion data format and the configuration modes used to
load the configuration data in the FPGA.
Lucent Technologies Inc.
41
ETC [ ETC ]
