P87LPC779FDH datasheet(63/74 Pages) PHILIPS

63 / 74 page

Philips Semiconductors

P87LPC779

CMOS single-chip 8-bit microcontroller

Product data

Rev. 02 — 03 May 2004

63 of 74

9397 750 13213

8.18.2

Security bits

When neither of the security bits are programmed, the code in the EPROM can be

veriﬁed. When only security bit 1 is programmed, all further programming of the

EPROM is disabled. At that point, only security bit 2 may still be programmed. When

both security bits are programmed, EPROM verify is also disabled.

0 1 0

Low frequency crystal, 20 kHz to 100 kHz.

0 0 1

Medium frequency crystal or resonator, 100 kHz to 4 MHz.

0 0 0

High frequency crystal or resonator, 4 MHz to 20 MHz.

Table 51:

UCFG2 - EPROM system conﬁguration byte 2 register (address FD01H) bit

allocation

Unprogrammed value: FFH

Bit

Symbol

SB2

SB1

Table 52:

UCFG2 - EPROM system conﬁguration byte 2 register (address FD01H) bit

description

Bit

Symbol

Description

7, 6

SB2, SB1

EPROM security bits. See Table 53 for details.

5-0

Reserved for future use.

Table 50:

FOSC2-FOSC0 oscillator conﬁguration…continued

FOSC2-FOSC0

Oscillator conﬁguration

Table 53:

EPROM security bits

SB2

SB1

Protection description

Both security bits unprogrammed. No program security features

enabled. EPROM is programmable and veriﬁable.

Only security bit 1 programmed. Further EPROM programming is

disabled. Security bit 2 may still be programmed.

Only security bit 2 programmed. This combination is not supported.

Both security bits programmed. All EPROM veriﬁcation and

programming are disabled.

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