2-15
Architecture
Lattice Semiconductor LatticeECP/EC Family Data Sheet
Figure 2-17. Comparison of General DSP and LatticeECP-DSP Approaches
sysDSP Block Capabilities
The sysDSP block in the LatticeECP-DSP family supports four functional elements in three 9, 18 and 36 data path
widths. The user selects a function element for a DSP block and then selects the width and type (signed/unsigned)
of its operands. The operands in the LatticeECP-DSP family sysDSP Blocks can be either signed or unsigned but
not mixed within a function element. Similarly, the operand widths cannot be mixed within a block.
The resources in each sysDSP block can be configured to support the following four elements:
• MULT (Multiply)
•MAC (Multiply, Accumulate)
• MULTADD (Multiply, Addition/Subtraction)
• MULTADDSUM (Multiply, Addition/Subtraction, Accumulate)
The number of elements available in each block depends in the width selected from the three available options x9,
x18, and x36. A number of these elements are concatenated for highly parallel implementations of DSP functions.
Table 2-1 shows the capabilities of the block.
Table 2-7. Maximum Number of Elements in a Block
Some options are available in four elements. The input register in all the elements can be directly loaded or can be
loaded as shift register from previous operand registers. In addition by selecting ‘dynamic operation’ in the ‘Signed/
Unsigned’ options the operands can be switched between signed and unsigned on every cycle. Similarly by select-
ing ‘Dynamic operation’ in the ‘Add/Sub’ option the Accumulator can be switched between addition and subtraction
on every cycle.
Width of Multiply x9 x18 x36
MULT 8 4 1
MAC 4 2 —
MULTADD 4 2 —
MULTADDSUM 2 1 —
Multiplier 0
Operand
A
Operand
B
Operand
A
Operand
B
Operand
A
Operand
B
Multiplier 1
Multiplier
(k-1)
Accumulator
Output
m/k
loopsSingle
Multiplier
x
xx
x
Operand
A
Accumulator
Operand
B
M loops
Function implemented in
General purpose DSP
Function implemented
in LatticeECP
Σ
Σ
