PIC24FJ256DA206 datasheet(78/408 Pages) MICROCHIP

78 / 408 page

PIC24FJ256DA210 FAMILY

DS39969B-page 78

 2010 Microchip Technology Inc.

4.3.3

READING DATA FROM PROGRAM

MEMORY USING EDS

The upper 32 Kbytes of data space may optionally be

mapped into any 16K word page of the program space.

This provides transparent access of stored constant

data from the data space without the need to use

special instructions (i.e., TBLRDL/H).

Program space access through the data space occurs

when the MSb of EA is ‘1’ and the DSRPAG<9> is also

‘1’. The lower 8 bits of DSRPAG are concatenated to the

Wn<14:0> bits to form a 23-bit EA to access program

memory. The DSRPAG<8> decides which word should

be addressed; when the bit is ‘0’, the lower word and

when ‘1’, the upper word of the program memory is

accessed.

The entire program memory is divided into 512 EDS

pages, from 0x200 to 0x3FF, each consisting of 16K

words of data. Pages, 0x200 to 0x2FF, correspond to

the lower words of the program memory, while 0x300 to

0x3FF correspond to the upper words of the program

memory.

Using this EDS technique, the entire program memory

can be accessed. Previously, the access to the upper

word of the program memory was not supported.

Table 4-37 provides the corresponding 23-bit EDS

address for program memory with EDS page and

source addresses.

For operations that use PSV and are executed outside

a REPEAT loop, the MOV and MOV.D instructions will

require one instruction cycle in addition to the specified

execution time. All other instructions will require two

instruction cycles in addition to the specified execution

time.

For operations that use PSV, which are executed inside

a REPEAT loop, there will be some instances that

require two instruction cycles in addition to the

specified execution time of the instruction:

• Execution in the first iteration

• Execution in the last iteration

• Execution prior to exiting the loop due to an

interrupt

• Execution upon re-entering the loop after an

interrupt is serviced

Any other iteration of the REPEAT loop will allow the

instruction accessing data, using PSV, to execute in a

single cycle.

TABLE 4-37:

EDS PROGRAM ADDRESS WITH DIFFERENT PAGES AND ADDRESSES

DSRPAG

(Data Space Read Register)

Source Address

while Indirect

Addressing

23-Bit EA Pointing to EDS

Comment

0x200

0x8000 to 0xFFFF

0x000000 to 0x007FFE

Lower words of 4M

program instructions;

(8 Mbytes) for read

operations only.

•

0x2FF

0x7F8000 to 0x7FFFFE

0x300

0x000001 to 0x007FFF

Upper words of 4M

program instructions

(4 Mbytes remaining,

4 Mbytes are phantom

bytes) for read

operations only.

•

0x3FF

0x7F8001 to 0x7FFFFF

0x000

Invalid Address

Address error trap(1)

Note 1:

When the source/destination address is above 0x8000 and DSRPAG/DSWPAG is ‘0’, an address error

trap will occur.

PIC24FJ256DA206 Datasheet(PDF) 78 Page - Microchip Technology

PIC24FJ256DA206 Datasheet(HTML) 78 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL