PIC18CXX2
18.4
Program Verification/Code Protection
18.6
In-Circuit Serial Programming
If the code protection bit(s) have not been pro-
grammed, the on-chip program memory can be read
out for verification purposes.
PIC18CXXX microcontrollers can be serially pro-
grammed while in the end application circuit. This is
simply done with two lines for clock and data, and three
other lines for power, ground and the programming volt-
age. This allows customers to manufacture boards with
unprogrammed devices, and then program the micro-
controller just before shipping the product. This also
allows the most recent firmware or a custom firmware
to be programmed.
Note: Microchip Technology does not recom-
mend code protecting windowed devices.
18.5
ID Locations
Five memory locations (200000h - 200004h) are desig-
nated as ID locations, where the user can store check-
sum or other code-identification numbers. These
locations are accessible during normal execution
through the TBLRD instruction or during program/ver-
ify. The ID locations can be read when the device is
code protected.
7/99 Microchip Technology Inc.
Preliminary
DS39026B-page 189
MICROCHIP [ MICROCHIP ]
