PIC24H Microchip Technology, PIC24H Datasheet - Page 64

• Manufacturer Part Number: PIC24H
• Description: Flash Programming Specification
• Manufacturer: Microchip Technology

dsPIC33F/PIC24H PROGRAMMING SPECIFICATION
5.8
Reading from code memory is performed by executing
a series of TBLRD instructions and clocking out the data
using the REGOUT command.
Table 5-9 shows the ICSP programming details for
reading code memory. In Step 1, the Reset vector is
exited. In Step 2, the 24-bit starting source address for
reading is loaded into the TBLPAG register and W6
register. The upper byte of the starting source address
is stored in TBLPAG and the lower 16 bits of the source
address are stored in W6.
TABLE 5-9:
DS70152D-page 64
Step 1: Exit Reset vector.
Step 2: Initialize TBLPAG and the read pointer (W6) for TBLRD instruction.
Step 3: Initialize the write pointer (W7) to point to the VISI register.
Step 4: Read and clock out the contents of the next two locations of code memory, through the VISI register, using
Step 5: Repeat step 4 until all desired code memory is read.
Step 6: Reset device internal PC.
Command
(Binary)
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0001
0000
0000
0000
0001
0000
0000
Reading Code Memory
the REGOUT command.
SERIAL INSTRUCTION EXECUTION FOR READING CODE MEMORY
000000
000000
040200
000000
200xx0
880190
2xxxx6
207847
000000
BA1B96
000000
000000
<VISI>
BA9BB6
000000
000000
<VISI>
040200
000000
(Hex)
Data
NOP
NOP
GOTO
NOP
MOV
MOV
MOV
MOV
NOP
TBLRDL [W6], [W7]
NOP
NOP
Clock out contents of VISI register
TBLRDH [W6++], [W7]
NOP
NOP
Clock out contents of VISI register
GOTO
NOP
0x200
#<SourceAddress23:16>, W0
W0, TBLPAG
#<SourceAddress15:0>, W6
#VISI, W7
0x200
Preliminary
To minimize the reading time, the packed instruction
word format that was utilized for writing is also used for
reading (see Figure 5-6). In Step 3, the write pointer,
W7, is initialized. In Step 4, two instruction words are
read from code memory and clocked out of the device,
through the VISI register, using the REGOUT command.
Step 4 is repeated until the desired amount of code
memory is read.
Description
© 2007 Microchip Technology Inc.
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