X88C75PI datasheet(8/27 Pages) XICOR

8 / 27 page

X88C75 SLIC® E2

Figure 8. Setting the SFR Map Register

Figure 9. Setting Program Memory Map Register

BITS 7:6

Setting these two bits to any combination other than “00”

or “11” will interfere with device proper operation.

E2 Memory Map Register (EEM)

Default = 08

LAM

RST

A15

A14

A13

2887 ILL F11

543

A15-A13

Modifying these three bits changes the location of the

program memory within the address map.The A15-A13

correspond to the upper three address bits of the 8K-

byte page where program memory will be mapped.

RST

The RST bit controls the polarity of the RESET input pin.

“0” = RESET is Active LOW

“1” = RESET is Active HIGH

LAM

Port B can be configured as either a general purpose

I/O port (normal I/O mode), or latched address mode

(LAM). The LAM option programs port B to output the

demultiplexed low order byte of the address latched into

the X88C75 by ALE. The LAM bit selects between these

two modes.

“0” = PORT B is I/O Port

“1” = Port B outputs low address byte (A7-A0)

Setting the Mapping Registers

The mapping registers are written using a modified

version of the Software Data Protection sequence. All

timings must adhere to the normal Software Data Pro-

tection sequence.

The complemented contents of the SFR map register

and the E2 memory map register can be read by the

microcontroller at their corresponding SFR addresses.

The physical memory location of these registers can be

derived by adding the following offset to the SFR base

address:

SFR Map Register

00H

E2 Memory Map Register

38H

If the regions specified in the map registers overlap, only

the SFR will be accessible.

P 555

b1 b0

AAA

b1 b0

P 555

b1 b0

P 555

b1 b0

Delay of tWC

Exit Routine

2887 ILL F12.1

b1 b0

XXX

Desired

Value

b1 b0

X = Don’t Care

B[2:0] = E2M [2:0]

P = Address bit (A12) of the

memory plane not being read.

P 555

b1 b0

AAA

b1 b0

P 555

b1 b0

P 555

b1 b0

2887 ILL F13.1

b1 b0

XXX

Desired

Value

b1 b0

Delay of tWC

Exit Routine

X = Don’t Care

B[2:0] = E2M [2:0]

P = Address bit (A12) of the

memory plane not being read.

X88C75PI Datasheet(PDF) 8 Page - Xicor Inc.

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