UPSD3212C, UPSD3212CV
Product Term Allocator
The CPLD has a Product Term Allocator. PSDsoft
uses the Product Term Allocator to borrow and
place product terms from one macrocell to anoth-
er. The following list summarizes how product
terms are allocated:
This is called product term expansion. PSDsoft
Express performs this expansion as needed.
Loading and Reading the Output Macrocells
(OMC). The Output Macrocells (OMC) block oc-
cupies a memory location in the MCU address
space, as defined by the CSIOP block (see the
section entitled “I/O PORTS (PSD MODULE),” on
page 104). The flip-flops in each of the 16 Output
Macrocells (OMC) can be loaded from the data
bus by a MCU. Loading the Output Macrocells
(OMC) with data from the MCU takes priority over
internal functions. As such, the preset, clear, and
clock inputs to the flip-flop can be overridden by
the MCU. The ability to load the flip-flops and read
them back is useful in such applications as load-
able counters and shift registers, mailboxes, and
handshaking protocols.
■ McellAB0-McellAB7 all have three native
product terms and may borrow up to six more
■ McellBC0-McellBC3 all have four native product
terms and may borrow up to five more
■ McellBC4-McellBC7 all have four native product
terms and may borrow up to six more.
Each macrocell may only borrow product terms
from certain other macrocells. Product terms al-
ready in use by one macrocell are not available for
another macrocell.
If an equation requires more product terms than
are available to it, then “external” product terms
are required, which consume other Output Macro-
cells (OMC). If external product terms are used,
extra delay is added for the equation that required
the extra product terms.
Data can be loaded to the Output Macrocells
(OMC) on the trailing edge of WRITE Strobe (WR,
edge loading) or during the time that WRITE
Strobe (WR) is active (level loading). The method
of loading is specified in PSDsoft Express Config-
uration.
Figure 51. CPLD Output Macrocell
MASK
REG.
MACROCELL CS
RD
MCU DATA BUS
[
]
D 7:0
WR
PT
ALLOCATOR
DIRECTION
REGISTER
(
)
ENABLE .OE
(
)
PRESET .PR
COMB/REG
SELECT
PT
PT
DIN PR
LD
MUX
I/O PIN
MACROCELL
ALLOCATOR
Q
PT
POLARITY
SELECT
IN
CLR
PROGRAMMABLE
PORT
DRIVER
(
)
CLEAR .RE
(
)
FF D/T/JK/SR
PT CLK
CLKIN
MUX
(
)
FEEDBACK .FB
PORT INPUT
INPUT
MACROCELL
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STMICROELECTRONICS [ ST ]
