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sadhana
Visitor II
August 14, 2003
Question

Mapping external RAM tp address 0.

  • August 14, 2003
  • 2 replies
  • 748 views
Posted on August 14, 2003 at 07:40

Mapping external RAM tp address 0.

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    2 replies

    S
    sadhanaAuthor
    Visitor II
    August 14, 2003
    Posted on August 14, 2003 at 05:02

    I read the user manual for ST10 F280. But didn't understand how to map the external memory to address 0. Can anybody help me out in this regard?

    Thanks in Advance.

    C
    charles239955_st
    Visitor II
    August 14, 2003
    Posted on August 14, 2003 at 07:40

    The ST10 devices always start executing code from address 0. Depending on the level of the /EA pin the internal Flash will be activated or not.

    If /EA is low at reset disables the internal Flash and the ST10 fetches code at address 0 using the external bus by activating BUSCON0. BUSCON0 value is set up by hardware depending on the configuration of the Port0 at reset. The lines Port0 6 and 7 will configure the BTYP field of the BUSCON0 register: 00 for 8 bit data bus and demultiplexed addresses. Check the user manual section 19.7.1: System Start-up configuration for more details.

    Note: the default number of wait states will be 15 but this can be reprogrammed by software.
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