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Last Post 19 Jul 2005 12:34 PM by  abest
Reconfiguring Bank Configuration Register
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abest
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15 Jun 2005 09:39 AM
    Just have a quick question,

    We have a NVRAM/RTC on our app board mapped in the address space starting @ 0x6300.0000. The problem is that the NVRAM/RTC has an 8-bit wide data bus (currently looking for 16-bit alternatives). We ran into the problem of the CPLD not generating a nIOWR signal when attempting to write misaligned data. I tried using the UNALIGNED macro, but it did not seem to work.

    Played around a little bit and reconfigured the memory width of the Bank 6 Configuration Register (BCR6) to 8-bits from the default 16. We are not using an ISA devices in the system, but want the option to use the CF to remain open.

    So here are my question:
    If the memory width of BCR6 is 8-bit, how will this affect writes to the CF?

    Do the BCRx registers only get initialized, when the kernel is starting?



    Thanks,
    Adam B.
    Candela Corporation
    mikea@logicpd.com
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    14 Jul 2005 10:36 AM
    Adam,
    Have you been able to find a solution yet? You should be able to use a 8-bit RTC in this area. You will likely need to hook address line A0 of the device to A1 of the Card Engine/Processor, and so on.
    When doing this, you'll need to watch your software as your addressing will be a bit different because you no longer have A0, but instead are starting with A1.

    So, instead, your addressing would map this way:
    Device -> Software Address
    0x00 -> 0x00
    0x01 -> 0x02
    0x02 -> 0x04
    0x03 -> 0x06
    ... and so on

    Thanks,
    -Mike A.
    abest
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    19 Jul 2005 12:34 PM
    Hey Mike,

    Yes we resolved the issue. I just took a look at your other posts regarding the ISA-LIKE bus & external device mapping. We implemented a similar solution. We reconfigured our hardware to be within the memory range of Bank 1 so that it is now enabled by nCS1. This solution gives us control of BCR1 and allows us to setup a scheme for mapping our peripheral(s).

    Thanks for the reply.

    Adam
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