Datasheet

© 2009 Microchip Technology Inc. DS70175H-page 213
PIC24HJXXXGPX06/X08/X10
21.0 SPECIAL FEATURES
PIC24HJXXXGPX06/X08/X10 devices include several
features intended to maximize application flexibility and
reliability, and minimize cost through elimination of
external components. These are:
• Flexible Configuration
• Watchdog Timer (WDT)
• Code Protection and CodeGuard™ Security
• JTAG Boundary Scan Interface
• In-Circuit Serial Programming™ (ICSP™)
programming capability
• In-Circuit Emulation
21.1 Configuration Bits
The Configuration bits can be programmed (read as
‘0’), or left unprogrammed (read as ‘1’), to select vari-
ous device configurations. These bits are mapped
starting at program memory location 0xF80000.
The device Configuration register map is shown in
Table 21-1.
The individual Configuration bit descriptions for the
FBS, FSS, FGS, FOSCSEL, FOSC, FWDT and FPOR
Configuration registers are shown in Table 21-2.
Note that address 0xF80000 is beyond the user program
memory space. In fact, it belongs to the configuration
memory space (0x800000-0xFFFFFF), which can only
be accessed using table reads and table writes.
The upper byte of all device Configuration registers
should always be ‘1111 1111’. This makes them
appear to be NOP instructions in the remote event that
their locations are ever executed by accident. Since
Configuration bits are not implemented in the
corresponding locations, writing ‘1’s to these locations
has no effect on device operation.
To prevent inadvertent configuration changes during
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 that power to the device
be cycled.
TABLE 21-1: DEVICE CONFIGURATION REGISTER MAP
Note: This data sheet summarizes the features
of the PIC24HJXXXGPX06/X08/X10 fam-
ilies of devices. However, it is not intended
to be a comprehensive reference source.
To complement the information in this data
sheet, refer to Section 23. “Code-
Guard™ Security” (DS70239), Section
24. “Programming and Diagnostics”
(DS70246), and Section 25. “Device
Configuration” (DS70231) in the
“PIC24H Family Reference Manual”,
which is available from the Microchip web
site (www.microchip.com).
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0xF80000 FBS
RBS<1:0> — — BSS<2:0> BWRP
0xF80002 FSS RSS<1:0>
— — SSS<2:0> SWRP
0xF80004 FGS
— — — — — GSS<1:0> GWRP
0xF80006 FOSCSEL IESO Reserved
(2)
— — —FNOSC<2:0>
0xF80008 FOSC FCKSM<1:0>
— — — OSCIOFNC POSCMD<1:0>
0xF8000A FWDT FWDTEN WINDIS
— WDTPRE WDTPOST<3:0>
0xF8000C FPOR — — — — —FPWRT<2:0>
0xF8000E FICD Reserved
(1)
JTAGEN — — —ICS<1:0>
0xF80010 FUID0 User Unit ID Byte 0
0xF80012 FUID1 User Unit ID Byte 1
0xF80014 FUID2 User Unit ID Byte 2
0xF80016 FUID3 User Unit ID Byte 3
Note 1: When read, these bits will appear as ‘1’. When you write to these bits, set these bits to ‘1’.
2: When read, this bit returns the current programmed value.