LFECP40 Lattice Semiconductor, LFECP40 Datasheet - Page 16

• Manufacturer Part Number: LFECP40
• Description: (LFEC Series) LatticeECP/EC Family Data Sheet
• Manufacturer: Lattice Semiconductor

Lattice Semiconductor
Memory Cascading
Larger and deeper blocks of RAMs can be created using EBR sysMEM Blocks. Typically, the Lattice design tools
cascade memory transparently, based on specific design inputs.
Single, Dual and Pseudo-Dual Port Modes
Figure 2-15 shows the four basic memory configurations and their input/output names. In all the sysMEM RAM
modes the input data and address for the ports are registered at the input of the memory array. The output data of
the memory is optionally registered at the output.
Figure 2-15. sysMEM EBR Primitives
The EBR memory supports three forms of write behavior for single port or dual port operation:
1. Normal – data on the output appears only during read cycle. During a write cycle, the data (at the current
2. Write Through – a copy of the input data appears at the output of the same port, during a write cycle.
3. Read-Before-Write – when new data is being written, the old content of the address appears at the output.
Memory Core Reset
The memory array in the EBR utilizes latches at the A and B output ports. These latches can be reset asynchro-
nously or synchronously. RSTA and RSTB are local signals, which reset the output latches associated with Port A
and Port B respectively. The Global Reset (GSRN) signal resets both ports. The output data latches and associated
resets for both ports are as shown in Figure 2-16.
address) does not appear on the output.
AD[12:0]
AD[12:0]
DI[35:0]
CS[2:0]
CS[2:0]
RST
RST
CLK
CLK
WE
CE
CE
Single Port RAM
ROM
EBR
EBR
DO[35:0]
DO[35:0]
2-13
ADW[12:0]
DOA[17:0]
ADA[12:0]
DIA[17:0]
CSA[2:0]
DI[35:0]
CS[2:0]
CLKW
CLKA
RSTA
CEW
WEA
CEA
RST
WE
Pseudo-Dual Port RAM
True Dual Port RAM
EBR
EBR
LatticeECP/EC Family Data Sheet
ADB[12:0]
DIB[17:0]
CEB
CLKB
RSTB
WEB
CSB[2:0]
DOB[17:0]
ADR[12:0]
DO[35:0]
CER
CLKR
Architecture