Lattice Semiconductor
•
•
•
•
•
•
Block CLK2
Block CLK3
PT Clock
PT Clock Inverted
Shared PT Clock
Ground
ispMACH 4000V/B/C/Z Family Data Sheet
Clock Enable Multiplexer
Each macrocell has a 4:1 clock enable multiplexer. This allows the clock enable signal to be selected from the fol-
lowing four sources:
•
•
•
•
PT Initialization/CE
PT Initialization/CE Inverted
Shared PT Clock
Logic High
Initialization Control
The ispMACH 4000 family architecture accommodates both block-level and macrocell-level set and reset capability.
There is one block-level initialization term that is distributed to all macrocell registers in a GLB. At the macrocell
level, two product terms can be “stolen” from the cluster associated with a macrocell to be used for set/reset func-
tionality. A reset/preset swapping feature in each macrocell allows for reset and preset to be exchanged, providing
flexibility.
Note that the reset/preset swapping selection feature affects power-up reset as well. All flip-flops power up to a
known state for predictable system initialization. If a macrocell is configured to SET on a signal from the block-level
initialization, then that macrocell will be SET during device power-up. If a macrocell is configured to RESET on a
signal from the block-level initialization or is not configured for set/reset, then that macrocell will RESET on power-
up. To guarantee initialization values, the V
CC
rise must be monotonic, and the clock must be inactive until the reset
delay time has elapsed.
GLB Clock Generator
Each ispMACH 4000 device has up to four clock pins that are also routed to the GRP to be used as inputs. These
pins drive a clock generator in each GLB, as shown in Figure 6. The clock generator provides four clock signals that
can be used anywhere in the GLB. These four GLB clock signals can consist of a number of combinations of the
true and complement edges of the global clock signals.
Figure 6. GLB Clock Generator
CLK0
Block CLK0
CLK1
Block CLK1
CLK2
Block CLK2
CLK3
Block CLK3
8
LATTICE [ LATTICE SEMICONDUCTOR ]
