Microchip Technology XC8 Standard Compiler (Workstation) SW006021-1 SW006021-1 ユーザーズマニュアル
製品コード
SW006021-1
C Language Features
2012 Microchip Technology Inc.
DS52053B-page 139
5.3.7
ID Locations
The 8-bit PIC devices have locations outside the addressable memory area that can be
used for storing program information, such as an ID number. For PIC18 devices, the
config
used for storing program information, such as an ID number. For PIC18 devices, the
config
pragma is also used to place data into these locations by using a special
register name. The pragma is used as follows.
#pragma config IDLOCx = value
where x is the number (position) of the ID location, and value is the nibble or byte
which is to be positioned into that ID location. If value is larger than the maximum
value allowable for each location on the target device, the value will be truncated and
a warning message issued. The size of each ID location varies from device to device.
See your device data sheet for more information.
which is to be positioned into that ID location. If value is larger than the maximum
value allowable for each location on the target device, the value will be truncated and
a warning message issued. The size of each ID location varies from device to device.
See your device data sheet for more information.
For example:
#pragma config IDLOC0 = 1
#pragma config IDLOC1 = 4
will attempt fill the first two ID locations with 1 and 4. One pragma can be used to pro-
gram several locations by separating each register-value pair with a comma. For
example, the above could also be specified as shown below.
gram several locations by separating each register-value pair with a comma. For
example, the above could also be specified as shown below.
#pragma config IDLOC0 = 1, IDLOC1 = 4
The config pragma does not produce executable code and so should ideally be placed
outside function definitions.
outside function definitions.
The compiler also has legacy support for the __IDLOC macro. This macro must be
used for baseline and mid-range devices. The macro is used in a manner similar to:
used for baseline and mid-range devices. The macro is used in a manner similar to:
#include <xc.h>
__IDLOC(x);
where x is a list of nibbles which are positioned into the ID locations. Only the lower
four bits of each ID location is programmed, so the following:
four bits of each ID location is programmed, so the following:
__IDLOC(15F0);
will attempt to fill ID locations with the values: 1, 5, F and 0.
To use this macro, ensure you include <xc.h> in your source file.
The __IDLOC macro does not produce executable code and so should ideally be
placed outside function definitions.
placed outside function definitions.
Some devices permit programming up to seven bits within each ID location. The
__IDLOC()
__IDLOC()
macro is not suitable for such devices and the __IDLOC7(a,b,c,d)
macro should be used instead. The parameters a to d are the values to be pro-
grammed. The values can be entered in either decimal or hexadecimal format, such as:
grammed. The values can be entered in either decimal or hexadecimal format, such as:
__IDLOC7(0x7f,1,70,0x5a);
It is not appropriate to use the __IDLOC7() macro on a device that does not permit
seven-bit programming of ID locations.
seven-bit programming of ID locations.