PIC24H datasheet(55/290 Pages) MICROCHIP

55 / 290 page

Preliminary

DS70175D-page 55

PIC24H

4.0

FLASH PROGRAM MEMORY

The PIC24H devices contain internal Flash program

memory for storing and executing application code.

The memory is readable, writable and erasable during

normal operation over the entire VDD range.

Flash memory can be programmed in two ways:

In-Circuit Serial Programming™ (ICSP™)

programming capability

Run-Time Self-Programming (RTSP)

ICSP programming capability allows a PIC24H device

to be serially programmed while in the end application

circuit. This is simply done with two lines for program-

ming clock and programming data (one of the alternate

programming pin pairs: PGC1/PGD1, PGC2/PGD2 or

PGC3/PGD3, and three other lines for power (VDD),

ground (VSS) and Master Clear (MCLR). This allows

customers to manufacture boards with unprogrammed

devices and then program the digital signal controller

just before shipping the product. This also allows the

most recent firmware or a custom firmware to be

programmed.

RTSP is accomplished using TBLRD (table read) and

TBLWT

(table write) instructions. With RTSP, the user

can write program memory data either in blocks or

‘rows’ of 64 instructions (192 bytes) at a time, or single

instructions and erase program memory in blocks or

‘pages’ of 512 instructions (1536 bytes) at a time.

4.1

Table Instructions and Flash

Programming

Regardless of the method used, all programming of

Flash memory is done with the table read and table

write instructions. These allow direct read and write

access to the program memory space from the data

memory while the device is in normal operating mode.

The 24-bit target address in the program memory is

formed using bits<7:0> of the TBLPAG register and the

Effective Address (EA) from a W register specified in

the table instruction, as shown in Figure 4-1.

The TBLRDL and the TBLWTL instructions are used to

read or write to bits<15:0> of program memory.

TBLRDL

and TBLWTL can access program memory in

both Word and Byte modes.

The TBLRDH and TBLWTH instructions are used to read

or write to bits<23:16> of program memory. TBLRDH

and TBLWTH can also access program memory in Word

or Byte mode.

FIGURE 4-1:

ADDRESSING FOR TABLE REGISTERS

Note:

This data sheet summarizes the features

of this group of PIC24H devices. It is not

intended to be a comprehensive reference

source. To complement the information in

this data sheet, refer to the “dsPIC30F

Family Reference Manual” (DS70046).

Program Counter

24 bits

Program Counter

TBLPAG Reg

8 bits

Working Reg EA

16 bits

Byte

24-bit EA

1/0

Select

Using

Table Instruction

Using

User/Configuration

Space Select

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