PSD211R datasheet(10/51 Pages) STMICROELECTRONICS

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PSD211R Family

Name

Type

Description

This pin is for 8031 or compatible MCUs that use PSEN to

separate program space from data space. In this case, PSEN is

used for reads from the EPROM.

PSEN

Notes:

1) If your MCU does not output a PSEN signal, pull up this pin to

VCC.

2) In programming mode, this pin is pulsed between VPP and 0 V.

The following control signals can be connected to this port, based on

WR/VPP

your MCU (and the way you configure the PSD in PSDsoft):

1. WR—active-low write pulse.

R/W/VPP

2. R/W—active-high read/active-low write input.

Note: in programming mode, this pin must be tied to VPP.

The following control signals can be connected to this port, based on

RD/E

your MCU (and the way you configure the PSD in PSDsoft):

1. RD—active-low read input.

2. E—E clock input.

The following control signals can be connected to this port:

1. CSI-Active-low chip select input. If your MCU supports a chip

select output, and you want the PSD to save power when not

A19/CSI

selected, use this pin as a chip select input.

2. If you don’t wish to use the CSI feature, you may use this pin as

an additional input (logic or address) to the PAD. A19 can be

latched with ALE/AS, or be a transparent logic input.

PSD211R/ZPSD211R:

This pin is user-programmable and can be configured to reset on a

high- or low-level input. Reset must be applied for at least 100 ns.

Reset

ZPSD211RV:

This pin is not configurable, and the chip will only reset on an

active-low level input. Reset must be applied for at least 500 ns,

and no operations may take place for an additional 500 ns minimum.

(See Figure 8.)

ALE/AS

Connect ALE or AS to this pin. The polarity of this pin is configurable.

The trailing edge of ALE/AS latches all multiplexed address inputs.

PA0

PA1

PA2

These pins make up Port A. These port pins are configurable, and

PA3

I/O

can have the following functions: (see Figure 5)

PA4

1. MCU I/O—in this mode, the direction of the pin is defined by its

PA5

direction bit, which resides in the direction register.

PA6

2. Latched address output.

PA7

PB0

These pins make up Port B. These port pins are configurable, and

PB1

can have the following functions: (see Figure 6)

PB2

1. MCU I/O —in this mode, the direction of the pin is defined by its

PB3

I/O

direction bit, which resides in the direction register.

PB4

2. Chip select output —each of PB0-3 has four product terms

PB5

available per pin, while PB4-7 have 2 product terms each.

PB6

See Figure 4.

PB7

Legend: The Type column abbreviations are: I = input only; I/O = input/output; P = power.

Table 2.

PSD211R Pin

Descriptions

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