ST10F280_12 datasheet(43/239 Pages) STMICROELECTRONICS

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ST10F280

Internal Flash memory

Doc ID 8673 Rev. 3

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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

5.5.3

Programming examples

Most of the microcontroller programs are written in the C language where the data page

pointers are automatically set by the compiler. But because the C compiler may use the not

allowed direct addressing mode for Flash write addresses, it is necessary to program the

organizational Flash accesses (command sequences) with assembler in-line routines which

use indirect addressing.

Example 1: Performing the command Read/Reset

We assume that in the initialization phase the lowest 32K Bytes of Flash memory (sector 0)

have been mapped to segment 1.

According to the usual way of ST10 data addressing with data page pointers, address bit

A15 and A14 of a 16-bit command write address select the data page pointer (DPP) which

contains the upper 10-bit for building the 24-bit physical data address. Address bit A13...A0

represent the address offset. As the bit A14...A18 are "don’t care" when written a Flash

command in the Command Interface (CI), we can choose the most convenient DPPx

The following examples are making usage of DPP0. We just have to make sure, that DPP0

points to active Flash memory space.

To be independent of mapping of sector 0 we choose for all DPPs which are used for Flash

address handling, to point to segment 2.

For this reason we load DPP0 with value 08h (00 0000 l000b).

MOV R5, #01554h

;load auxilary register R5 with command address

;(used in command cycle 1)

MOV R6, #02AA8h

;load auxilary register R6 with command address

;(used in command cycle 2)

SCXT DPPO, #08h

;push data page pointer 0 and load it to point to

;segment 2

MOV R7, #0A8h

;load register R7 with 1st CI enable command

MOV [R5], R7

;command cycle 1

MOV R7, #054h

;load register R7 with 2cd CI enable command

MOV [R6], R7

;command cycle 2

MOV R7, #0F0h

;load register R7 with Read/Reset command

MOV [R5], R7

;command cycle 3. Address is don’t care

POP DPP0

;restore DPP0 value

In the example above the 16-bit registers R5 and R6 are used as auxiliary registers for

indirect addressing.

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