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ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller SPDIP 28 16-Bit 40 null I/O number 21

dsPIC33F/PIC24H PROGRAMMING SPECIFICATION

5.8 Reading Code Memory

Reading from code memory is performed by executing

a series of TBLRD instructions and clocking out the data

using the REGOUT command.

Table 5-8 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

is stored in TBLPAG and the lower 16 bits of the source

address are stored in W6.

To minimize the reading time, the packed instruction

word format that was utilized for writing is also used for

reading (see Figure 5-7). 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.

TABLE 5-8: SERIAL INSTRUCTION EXECUTION FOR READING CODE MEMORY

Command

(Binary)

Data

(Hex)

Description

Step 1: Exit the Reset vector.

0000

040200

000000

GOTO 0x200

NOP

Step 2: Initialize TBLPAG and the read pointer (W6) for TBLRD instruction.

0000

200xx0

880190

2xxxx6

MOV #<SourceAddress23:16>, W0

MOV W0, TBLPAG

MOV #<SourceAddress15:0>, W6

Step 3: Initialize the write pointer (W7) and store the next four locations of code memory to W0:W5.

0000

EB0380

000000

BA1B96

000000

BADBB6

000000

BADBD6

000000

BA1BB6

000000

BA1B96

000000

BADBB6

000000

BADBD6

000000

BA0BB6

000000

CLR W7

NOP

TBLRDL [W6], [W7++]

NOP

TBLRDH.B [W6++], [W7++]

NOP

TBLRDH.B [++W6], [W7++]

NOP

TBLRDL [W6++], [W7++]

NOP

TBLRDL [W6], [W7++]

NOP

TBLRDH.B [W6++], [W7++]

NOP

TBLRDH.B [++W6], [W7++]

NOP

TBLRDL [W6++], [W7]

NOP