UPSD3422 datasheet(213/293 Pages) STMICROELECTRONICS

213 / 293 page

uPSD34xx

PSD module

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The DPLD performs address decoding, and generates select signals for internal and

external components, such as memory, registers, and I/O ports. The DPLD can generate

External Chip-Select (ECS1-ECS2) signals on Port D.

The GPLD can be used for logic functions, such as loadable counters and shift registers,

state machines, encoding and decoding logic. These logic functions can be constructed

from a combination of 16 Output Macrocells (OMC), 20 Input Macrocells (IMC), and the

AND-OR Array.

Routing of the 16 OMCs outputs can be divided between pins on three Ports A, B, or C by

the OMC Allocator as shown in Figure 78 on page 221. Eight of the 16 OMCs that can be

routed to pins on Port A or Port B and are named MCELLAB0-MCELLAB7. The other eight

OMCs to be routed to pins on Port B or Port C and are named MCELLBC0-MCELLBC7.

This routing depends on the pin number assignments that are specified in PSDsoft Express

for “PLD Outputs” in the Pin Definition section. OMC outputs can also be routed internally

(not to pins) used as buried nodes to create shifters, counters, etc.

The AND-OR Array is used to form product terms. These product terms are configured from

the logic definitions entered in PSDsoft Express. A PLD Input Bus consisting of 69 signals is

connected to both PLDs. Input signals are shown in Table 111, both the true and

compliment versions of each of these signals are available at inputs to each PLD.

Note:

The 8032 data bus, D0 - D7, does not route directly to PLD inputs. Instead, the 8032 data

bus has indirect access to the GPLD (not the DPLD) when the 8032 reads and writes the

OMC and IMC registers within csiop address space.

28.5.25

Turbo bit and PLDs

The PLDs can minimize power consumption by going to standby after ALL the PLD inputs

remain unchanged for an extended time (about 70ns). When the Turbo Bit is set to logic one

(Bit 3 of the csiop PMMR0 Register), Turbo mode is turned off and then this automatic

standby mode is achieved. Turning off Turbo mode increases propagation delays while

reducing power consumption. The default state of the Turbo Bit is logic zero, meaning Turbo

mode is on. Additionally, four bits are available in the csiop PMMR0 and PMMR2 Registers

to block the 8032 bus control signals (RD, WR, PSEN, ALE) from entering the PLDs. This

reduces power consumption and can be used only when these 8032 control signals are not

used in PLD logic equations. See Section 28.5.51: Power management on page 241.

UPSD3422 Datasheet(PDF) 213 Page - STMicroelectronics