PIC18F2510 MICROCHIP [Microchip Technology], PIC18F2510 Datasheet - Page 77

• Manufacturer Part Number: PIC18F2510
• Description: 28/40/44-PIN FLASH MICROCONTROLLERS WITH 10-BIT A/D AND NANO WATT TECHNOLOGY
• Manufacturer: MICROCHIP [Microchip Technology]

6.0
In PIC18F2X1X/4X1X devices, the program memory is
implemented as read-only Flash memory. It is readable
over the entire V
read from program memory is executed on one byte at
a time.
6.1
For PIC18 devices, there are two operations that allow
the processor to move bytes between the program
memory space and the data RAM: table read (TBLRD)
and table write (TBLWT).
Table read operations retrieve data from program
memory and place it into the data RAM space.
Figure 6-1 shows the operation of a table read with
program memory and data RAM.
The program memory space is 16 bits wide, while the
data RAM space is 8 bits wide. Table reads and table
writes move data between these two memory spaces
through an 8-bit register, TABLAT.
FIGURE 6-1:
 2004 Microchip Technology Inc.
Note 1: Table Pointer register points to a byte in program memory.
TBLPTRU
FLASH PROGRAM MEMORY
Table Reads
DD
Table Pointer
TBLPTRH
range during normal operation. A
TABLE READ OPERATION
(1)
TBLPTRL
Program Memory
(TBLPTR)
Preliminary
Instruction: TBLRD*
Program Memory
Table reads work with byte entities. A table block
containing data, rather than program instructions, is not
required to be word-aligned. Therefore, a table block can
start and end at any byte address.
Because the program memory cannot be written to or
erased under normal operation, the TBLWT operation is
not discussed here.
Note 1: Although
PIC18F2X1X/4X1X
2: The TBLWT instruction is available only in
PIC18F2X1X/4X1X devices in normal
operation, the TBLWT instruction is still
implemented in the instruction set.
Executing the instruction takes two
instruction cycles, but effectively results
in a NOP.
programming modes and is used during
In-Circuit Serial Programming™ (ICSP™).
it
cannot
Table Latch (8-bit)
TABLAT
DS39636A-page 75
be
used
in