Section 4. Program Memory - Microchip Taiwan

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dsPIC33E/PIC24E Family Reference Manual4.5 PROGRAM SPACE VISIBILITY FROM DATA SPACEThe upper 32 Kbytes of the dsPIC33E/PIC24E data memory address space can optionally bemapped into any 16K word program space page. The PSV mode of operation providestransparent access of stored constant data from X data space without the need to use specialinstructions (i.e., TBLRD, TBLWT instructions).4.5.1 PSV ConfigurationThe dsPIC33E/PIC24E core extends the available data space through a paging scheme to makeit appear linear for pre- and post-modified effective addresses.The upper half of the base data space address (0x8000 to 0xFFFF) is used with the 10-bit DataSpace Read Page register (DSRPAG) to form a PSV address, and can address 8 Mbytes of PSVaddress space.The paged memory scheme provides access to multiple 32-Kbyte windows in the PSV memory.The PSV in the paged data memory space is illustrated in Figure 4-8.Program space (PS) can be read with a DSRPAG register of 0x200 or greater.Reads from PS are supported using the DSRPAG register. Writes to PS are not supported;therefore, the Data Space Write Page register (DSWPAG) is dedicated exclusively to data space(DS), including extended data space (EDS).For more information on the paged memory scheme refer to Section 3. “Data Memory”(DS70595).Note:The DSRPAG register can be written using the MOVPAG #lit10, DSRPAG instructionor the MOVPAG Wn, DSRPAG instruction. Refer to the “16-bit MCU and DSCProgrammer’s Reference Manual” (DS70157) for details.DS70613B-page 4-12© 2010 Microchip Technology Inc.
Section 4. Program MemoryFigure 4-8:PSV Memory Map16-bitData SpaceAddress[EA]DSRPAG = 1(PSV Access Enabled)0x00000x8000SFR andNon-MappableData Space(PAGE 0)DSRPAG = 1 DSRPAG = 0(MS-ByteAccess Enabled)(LS-WordAccess Enabled)24-bitProgram Space Address[0:DSRPAG:EA]0x000000MappableData SpacePSV PAGE0x300PSV PAGE0x2000xFFFF0x008000PSV PAGE0x301PSV PAGE0x2010x010000PSV PAGE0x302PSV PAGE0x2024PSV PAGE0x3FDPSV PAGE0x3FEPSV PAGE0x2FDPSV PAGE0x2FE0x7E80000x7F0000Program Memory0x7F8000PSV PAGE0x3FFPSV PAGE0x2FF0x7FFFFE© 2010 Microchip Technology Inc. DS70613B-page 4-13
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Section 4. Program Memory - Microchip Taiwan

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