ST10F269Z1Q6 datasheet(27/184 Pages) STMICROELECTRONICS

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ST10F269

5 - INTERNAL FLASH MEMORY

27/184

5.5.2 - Basic Flash Access Control

When accessing the Flash all command write addresses have to be located within the active Flash

memory space. The active Flash memory space is that logical address range which is covered by the

Flash after mapping. When using data page pointer (DPP) for addressing the Flash, make sure that

address bit A15 and A14 of the command addresses are reflected in both LSBs of the selected data page

pointer (A15 - DPPx.1 and A14 - DPPx.0).

In case of the command write addresses, address bit A14, A15 and above are don’t care. Thus, command

writes can be performed by only using one DPP register. This allow to have a more simple and compact

application software.

Another - advantageous - possibility is to use the extended segment instruction for addressing.

Note: The direct addressing mode is not allowed for write access to the Flash address/command

Flash module always the indirect addressing mode has to be selected.

The following basic instruction sequences show examples for different addressing possibilities.

Principle example of address generation for Flash commands and registers:

When using data page pointer (DPP0 is this example)

MOV

DPP0,#08h

;adjust data page pointers according to the

;addresses: DPP0 is used in this example, thus

;ADDRESS must have A14 and A15 bit set to ‘0’.

MOV

Rwm,#ADDRESS

;ADDRESS could be a dedicated command sequence

;address 2AA8h, 1554h ... ) or the Flash write

;address

MOV

Rwn,#DATA

;DATA could be a dedicated command sequence data

;(xxA0h,xx80h ... ) or data to be programmed

MOV

[Rwm],Rwn

;indirect addressing

When using the extended segment instruction:

MOV

Rwm,#ADDRESS

;ADDRESS could be a dedicated command sequence

;address (2AA8h, 1554h ... ) or the Flash write

;address

MOV

Rwo,#DATA

;DATA could be a dedicated command sequence data

;(xxA0h,xx80h ... ) or data to be programmed

MOV

Rwn,#SEGMENT

;the value of SEGMENT represents the segment

;number and could be 0, 1, 2, 3 or 4 (depending

;on sector mapping) for 256KByte Flash.

EXTS

Rwn,#LENGTH

;the value of Rwn determines the 8-bit segment

;valid for the corresponding data access for any

;long or indirect address in the following(s)

;instruction(s). LENGTH defines the number of

;the effected instruction(s) and has to be a value

;between 1...4

MOV

[Rwm],Rwo

;indirect addressing with segment number from

;EXTS

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