UPSD3422 datasheet(216/293 Pages) STMICROELECTRONICS

216 / 293 page

PSD module

uPSD34xx

216/293

28.5.26

Decode PLD (DPLD)

The DPLD (Figure 75 on page 217) generates the following memory decode signals:

●

Eight Main Flash memory sector select signals (FS0-FS7) with three product terms

each

●

Four Secondary Flash memory sector select signals (CSBOOT0-CSBOOT3) with three

product terms each

●

One SRAM select signal (RS0) with two product terms

●

One select signal for the base address of 256 PSD Module device control and status

registers (csiop) with one product term

●

Two external chip-select output signals for Port D pins, each with one product term (52-

pin devices only have one pin on Port D)

●

Two chip-select signals (PSEL0, PSEL1) used to enable the 8032 data bus repeater

function (Peripheral I/O mode) for Port A on 80-pin devices. Each has one product

term.

A product term indicates the logical OR of two or more inputs. For example, three product

terms in a DPLD output means the final output signal is capable of representing the logical

OR of three different input signals, each input signal representing the logical AND of a

combination of the 69 PLD inputs.

Using the signal FS0 for example, the user may create a 3-product term chip select signal

that is logic true when any one of three different address ranges are true... FS0 = address

range 1 OR address range 2 OR address range 3.

The phrase “one product term” is a bit misleading, but commonly used in this context. One

product term is the logical AND of two or more inputs, with no OR logic involved at all, such

as the CSIOP signal in Figure 75 on page 217.

UPSD3422 bảng dữ liệu(PDF) 216 Page - STMicroelectronics