ECP2 datasheet(18/386 Pages) LATTICE

18 / 386 page

2-15

Architecture

Lattice Semiconductor

LatticeECP2/M Family Data Sheet

Primary Clock Routing

The clock routing structure in LatticeECP2/M devices consists of a network of eight primary clock lines (CLK0

through CLK7) per quadrant. The primary clocks of each quadrant are generated from muxes located in the center

of the device. All the clock sources are connected to these muxes. Figure 2-13 shows the clock routing for one

quadrant. Each quadrant mux is identical. If desired, any clock can be routed globally

Figure 2-13. Per Quadrant Primary Clock Selection

Dynamic Clock Select (DCS)

The DCS is a smart multiplexer function available in the primary clock routing. It switches between two independent

input clock sources without any glitches or runt pulses. This is achieved regardless of when the select signal is tog-

gled. There are two DCS blocks per quadrant; in total, there are eight DCS blocks per device. The inputs to the

DCS block come from the center muxes. The output of the DCS is connected to primary clocks CLK6 and CLK7

(see Figure 2-13).

Figure 2-14 shows the timing waveforms of the default DCS operating mode. The DCS block can be programmed

to other modes. For more information about the DCS, please see the list of additional technical documentation at

the end of this data sheet.

Figure 2-14. DCS Waveforms

Secondary Clock/Control Routing

Secondary clocks in the LatticeECP2 devices are region-based resources. The beneﬁt of region-based resources

is the relatively low injection delay and skew within the region, as compared to primary clocks. EBR/DSP rows and

a special vertical routing channel bound the secondary clock regions. This special vertical routing channel aligns

with either the left edge of the center DSP block in the DSP row or the center of the DSP row. Figure 2-15 shows

CLK0

CLK1

CLK2

CLK3

CLK4

CLK5

CLK6

CLK7

35:1

32:1

35:1

8 Primary Clocks (CLK0 to CLK7) per Quadrant

DCS

Primary Clock Sources: PLLs + DLLs + CLKDIVs + PIOs + Routing

CLK0

SEL

DCSOUT

CLK1

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