pic32mx320f064h Microchip Technology Inc., pic32mx320f064h Datasheet - Page 475

• Manufacturer Part Number: pic32mx320f064h
• Description: 64/100-pin General Purpose, 32-bit Flash Microcontrollers
• Manufacturer: Microchip Technology Inc.

25.1
In PIC32MX Family devices, the Configuration Words
select various device configurations. These Configu-
ration Words are implemented as volatile memory reg-
isters and must be loaded from the nonvolatile
programmed configuration data mapped in the last four
words (32-bit x 4 words)
DEVCFG0-DEVCFG3. These are the four locations an
external programming device programs with the appro-
priate configuration data (see Table 25-3).
TABLE 25-3:
On Power-on Reset (POR) or any Reset, the Configu-
ration Words are copied from boot FLASH memory to
their corresponding Configuration registers. A Config-
uration bit can only be programmed = 0 (unpro-
grammed state = 1). During programming, a
Configuration Word can be programmed a maximum of
two times before a page erase must be performed.
After programming the Configuration Words, the user
should reset the device to ensure the Configuration
registers are reloaded with the new programmed data.
25.1.1
To prevent inadvertent Configuration bit changes dur-
ing code execution, all programmable Configuration
bits are write-once. After a bit is initially programmed
during a power cycle, it cannot be written to again.
Changing a device configuration requires changes to
the configuration data in the boot Flash memory and
power to the device be cycled.
To ensure the 128-bit data integrity, a comparison is
continuously made between each Configuration bit and
its stored complement. If a mismatch is detected, a
Configuration Mismatch Reset is generated, causing a
device Reset.
© 2007 Microchip Technology Inc.
DEVCFG0
DEVCFG1
DEVCFG2
DEVCFG3
Configuration Word
Device Configuration
CONFIGURATION REGISTER
PROTECTION
DEVCFG LOCATIONS
of boot Flash memory,
0xBFC0_2FFC
0xBFC0_2FF8
0xBFC0_2FF4
0xBFC0_2FF0
Address
Advance Information
25.2
The PIC32MX Family features a single device code
protection bit, CP that when programmed = 0, protects
boot Flash and program Flash from being read or mod-
ified by an external programming device. When code
protection is enabled, only the Device ID and User ID
registers are available to be read by an external pro-
grammer. Boot Flash and program Flash memory are
not protected from self-programming during program
execution when code protection is enabled. See
Section 25.3 “Program Write Protection (PWP)”.
25.3
In addition to a device code protection bit, the
PIC32MX Family also features write protection bits to
prevent boot Flash and program Flash memory regions
from being written during code execution.
Boot Flash memory is write protected with a single
Configuration bit,
programmed = 0.
Program Flash memory can be write-protected entirely
or in selectable page sizes using Configuration bits
PWP<7:0> (DEVCFG0<19:12>). A page of Program
Flash memory is 4096 bytes (1024 words). The PWP
bits represent the one’s complement of the number of
protected pages. For example, programming PWP bits
= 0xFF selects 0 pages to be write-protected, effec-
tively disabling the program Flash write protection.
Programming PWP bits = 0xFE selects the first page to
be write protected. When enabled, the write-protected
memory range is inclusive from the beginning of pro-
gram Flash memory (0xBD00_0000) up through the
selected page. Refer to Table 25-4.
Note:
PIC32MX FAMILY
Device Code Protection
Program Write Protection (PWP)
The PWP bits represent the one’s
complement of the number of protected
pages.
BWP (DEVCFG0<24>), when
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