93C56A/B

DS21206B-page 6

Preliminary

© 1998 Microchip Technology Inc.

3.6

ERASE/WRITE Disable and Enable

(EWDS/EWEN)

The device powers up in the ERASE/WRITE Disable

(EWDS) state. All programming modes must be pre-

ceded by an ERASE/WRITE Enable (EWEN) instruc-

tion. Once

the

EWEN

instruction

is

executed,

programming remains enabled until an EWDS instruc-

protect against accidental data disturbance, the EWDS

instruction can be used to disable all ERASE/WRITE

functions and should follow all programming opera-

tions. Execution of a READ instruction is independent

of both the EWEN and EWDS instructions.

3.7

READ

The READ instruction outputs the serial data of the

addressed memory location on the DO pin. A dummy

zero bit precedes the 8-bit (93C56A) or 16-bit

(93C56B) output string. The output data bits will toggle

on the rising edge of the CLK and are stable after the

when CS is held high. The memory data will automati-

cally cycle to the next register and output sequentially.

FIGURE 3-4:

READ TIMING

FIGURE 3-5:

EWDS TIMING

FIGURE 3-6:

EWEN TIMING

CS

CLK

DI

DO

11

0

An

•••

A0

HIGH-Z

0Dx

•••

D0

Dx

•••

D0

•••

Dx

D0

CS

CLK

DI

10

00

0

X

•••

X

1X

CS

CLK

DI

00

1

1

X

•••