Architecture
LatticeECP2/M Family Data Sheet
Lattice Semiconductor
MAC sysDSP Element
In this case, the two operands, A and B, are multiplied and the result is added with the previous accumulated value.
This accumulated value is available at the output. The user can enable the input and pipeline registers, but the out-
put register is always enabled. The output register is used to store the accumulated value. The Accumulators in the
DSP blocks in the LatticeECP2/M family can be initialized dynamically. A registered overflow signal is also avail-
able. The overflow conditions are provided later in this document. Figure 2-24 shows the MAC sysDSP element.
Figure 2-24. MAC sysDSP
Serial Register B in
Multiplicand
Serial Register A in
Preload
m
m
Accumulator
m
n
Multiplier
n
m+n+16
(default)
Multiplier
m
n
Input Data
Register A
n
Output
m+n
m+n+16
(default)
x
(default)
Input Data
Register B
Pipeline
Register
n
n
Signed A
Signed B
Input
Register
Pipeline
Register
Overflow
signal
To Accumulator
To Accumulator
To Accumulator
Input
Register
Pipeline
Register
Input
Register
Pipeline
Register
Addn
CLK (CLK0,CLK1,CLK2,CLK3)
CE (CE0,CE1,CE2,CE3)
Accumsload
Input
Register
Pipeline
Register
To Accumulator
RST(RST0,RST1,RST2,RST3)
SROB
SROA
2-24
LATTICE [ LATTICE SEMICONDUCTOR ]
