Datasheet

PIC18F2XXX/4XXX FAMILY
DS39622L-page 28  2010 Microchip Technology Inc.
5.0 CONFIGURATION WORD
The PIC18F2XXX/4XXX family devices have several
Configuration Words. These bits can be set or cleared to
select various device configurations. All other memory
areas should be programmed and verified prior to setting
the Configuration Words. These bits may be read out
normally, even after read or code protection. See
Table 5-1 for a list of Configuration bits and Device IDs,
and Table 5-3 for the Configuration bit descriptions.
5.1 ID Locations
A user may store identification information (ID) in eight
ID locations, mapped in 200000h:200007h. It is recom-
mended that the most significant nibble of each ID be
Fh. In doing so, if the user code inadvertently tries to
execute from the ID space, the ID data will execute as
a NOP.
5.2 Device ID Word
The Device ID Word for the PIC18F2XXX/4XXX family
devices is located at 3FFFFEh:3FFFFFh. These bits
may be used by the programmer to identify what device
type is being programmed and read out normally, even
after code or read protection.
In some cases, devices may share the same DEVID
values. In such cases, the Most Significant bit of the
device revision, REV4 (DEVID1<4>), will need to be
examined to completely determine the device being
accessed.
See Table 5-2 for a complete list of Device ID values.
FIGURE 5-1: READ DEVICE ID WORD FLOW
Start
Set TBLPTR = 3FFFFE
Done
Read Low Byte
Read High Byte
with Post-Increment
with Post-Increment