UPSD33XX Datasheet, PDF (163/231 Pages) STMicroelectronics – Fast 8032 MCU with Programmable Logic

uPSD33xx
OMC Allocator. Outputs of the 16 OMCs can be
routed to a combination of pins on Port A (80-pin
devices only), Port B, or Port C as shown in Figure
67. OMCs are routed to port pins automatically af-
ter specifying pin numbers in PSDsoft Express.
Routing can occur on a bit-by-bit basis, spitting
OMC assignment between the ports. However,
one OMC can be routed to one only port pin, not
both ports.
Product Term Allocator. Each OMC has a Prod-
uct Term Allocator as shown in Figure
66., page 162. PSDsoft Express uses PT Alloca-
tors to give and take product terms to and from
other OMCs to fit a logic design into the available
silicon resources. This happens automatically in
PSDsoft Express, but understanding how PT allo-
cation works will help the user if the logic design
does not “fit,” in which case the user may try se-
lecting a different pin or different OMC for the logic
where more product terms may be available. The
following list summarizes how product terms are
allocated to each OMC, as shown in Table
85., page 164.
– MCELLAB0-MCELLAB7 each have three
native product terms and may borrow up to six
more
– MCELLBC0-MCELLBC3 each have four
native product terms and may borrow up to
five more
– MCELLBC4-MCELLBC7 each have four
native product terms and may borrow up to six
more.
Native product terms come from the AND-OR Ar-
ray. Each OMC may borrow product terms only
from certain other OMCs, if they are not in use.
Product term allocation does not add any propaga-
tion delay to the logic. The fitter report generated
by PSDsoft Express will show any PT allocation
that has occurred.
If an equation requires more product terms than
are available to it through PT allocation, then “ex-
ternal” product terms are required, which con-
sumes other OMCs. This is called product term
expansion and also happens automatically in PS-
Dsoft Express as needed. PT expansion causes
additional propagation delay because an addition-
al OMC is consumed by the expansion process
and it’s output is rerouted (or fed back) into the
AND-OR array. The user can examine the fitter re-
port generated by PSDsoft Express to see result-
ing PT allocation and PT expansion (expansion
will have signal names, such as ‘*.fb_0’ or ‘*.fb_1’).
PSDsoft Express will always try to fit the logic de-
sign first by using PT allocation, and if that is not
sufficient then PSDsoft Express will use PT expan-
sion.
Product term expansion may occur in the DPLD
for complex chip select equations for Flash mem-
ory sectors and for SRAM, but this is a rare oc-
curence. If PSDsoft Express does use PT
expansion in the DPLD, it results in an approxi-
mate 15ns additional propagation delay for that
chip select signal, which gives 15ns less time for
the memory to respond. Be aware of this and con-
sider adding a wait state to the 8032 bus access
(using the SFR named, BUSCON), or lower the
8032 clock frequency to avoid problems with
memory access time.
Figure 67. OMC Allocator
PORT A PINS
(80-pin pkg only)
76543210
PORT B PINS
76543210
PORT C PINS
7 * *432 * *
76543210 76543210
OMC Bank AB (MCELLAB0-7) OMC Bank BC (MCELLBC0-7)
* = Used for JTAG,
Pin Not Available
to GPLD
AI09177
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