SCS152

© 1997 Microchip Technology Inc.

Preliminary

DS40150B-page 5

3.1

Access Conditions

The condition codes are:

Note 1: If the access condition does not allow a command that modifies the EEPROM (i.e., BITPROG, ERASE or

DECR-ERASE), it will be converted into a RDBIT command.

2: The commands that can potentially change the EEPROM (even if it is converted into a RDBIT command) do

not increment the I/O address counter.

3: Any command that modifies the EEPROM checks the internal high voltage sensor during the programming

and goes into the standby state if the sensor indicates the internal high voltage was not high enough. Power

must be removed to clear this condition.

4: If the device is not in issuer mode and not in user mode, only BITPROG access is allowed to the CFG field.

TABLE 3-2:

ACCESS CONDITIONS IN ISSUER MODE

Field

RDBIT

BITPROG

ERASE

Extended Commands

CID

Y

F and TC

N

test modes

SER

Y

TC

N

BITPROG

O4…O1

Y

TC and Z

TC and B

DECR-ERASE: TC and Z

O0

Y

TC and Z

N

N

CFG

Y

TC

N

test modes

USER0

Y

Y

Y

BITPROG

UKEY0

‘1’

TC

TC

BITPROG

test modes

SIGN: Y

TABLE 3-3:

ACCESS CONDITIONS IN USER MODE

Field

RDBIT

BITPROG

ERASE

Extended Commands

CID

Y

N

N

test modes

SER

Y

N

N

BITPROG

O4…O1

Y

Z

B

DECR-ERASE: Z

O0

Y

Z

N

N

CFG

Y

Y

N

test modes

USER0

Y

L

L

BITPROG

UKEY0

‘1’

N

N

BITPROG

test modes

SIGN: Y

• Y

Command always allowed

• N

No access allowed and it is converted into a RDBIT command

• TC

Transport code must be submitted before the operation is allowed

• ‘1’

Output always logic high in this field

• F

Command allowed if the fuse is not blown

• Z

The digit code is nonzero

• B

Command allowed if previous operation was BITPROG and was successfully

• L

Command allowed if LOCK0 bit in the CFG field is ‘1’

• BITPROG

The BITPROG condition is checked and executed