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PIC18F24K40-I/SP 其他数据使用手册 - Microchip（微芯）
制造商:
Microchip（微芯）
分类:
微控制器
封装:
DIP-28
描述:
PIC18F24K40-I/SP 管装
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
PIC18F24K40-I/SP数据手册
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of 8 Go
若手册格式错乱，请下载阅览PDF原文件
PIC18F24/25K40
DS80000711A-page 4 2016 Microchip Technology Inc.
3. Module: PIC18 Core
3.1 TBLRD Requires NVMREG Value to Point to
Appropriate Memory
The affected silicon revisions of the PIC18FXXK40
devices improperly require the NVMREG<1:0>
bits in the NVMCON register to be set for TBLRD
access of the various memory regions. The issue
is most apparent in compiled C programs when the
user defines a const type and the compiler uses
TBLRD instructions to retrieve the data from pro-
gram Flash memory (PFM). The issue is also
apparent when the user defines an array in RAM
for which the complier creates start-up code, exe-
cuted before main(), that uses TBLRD instructions
to initialize RAM from PFM.
Work around
Assembly code:
Set the NVMREG<1:0> bits to select the
appropriate memory region before executing
TBLRD instructions.
C code:
Create an assembly file named powerup.as and
include this file with the other files in the project.
This file will change the NVMREG<1:0> bits to
point to program Flash before any code is
executed.
Contents of the powerup.as file:
#include <xc.inc>
GLOBAL powerup, start
PSECT powerup, class=CODE, delta=1,
reloc=2
powerup:
BSF NVMCON1, 7
GOTO start
end
If there is a need to change the NVMREG<1:0>
value to anything other than ‘10’ and the Interrupt
Service Routine uses constants or literal strings,
then interrupts must be disabled before the
change and restored to ‘10’ before interrupts are
enabled.
Affected Silicon Revisions
4. Module: Program Flash Memory
4.1 Endurance of PFM is Lower than Specified
The Flash memory cell endurance specification
(Parameter MEM30) is 1K cycles.
Work around
None.
Affected Silicon Revisions
A3
X
A3
X
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