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Last Post 26 Sep 2007 10:34 PM by  kurtl@logicpd.com
nIOWR and nIORD not strobing low
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marclai
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13 Jul 2007 12:28 PM
    Hi,
    I am trying to write a compact flash low level driver (memory mapped mode). When trying to write to the following compact flash registers (via 16 bit writes) I have found that the nIOWR signal does not strobe low as I expect. Also nIORD does not strobe low on reads. According to the logicpd IO controller specification the compact flash is mapped at memory address range 0x60200000 to 0x603FFFFF. Looking at the schematic REG is tied to uP_MA12 so the compact flash registers start at 0x60201000.

    When I am trying to write to “Sector Count”. All the address lines look correct.
    Also the control lines are as follows:

    nMWR = 0
    CF_nCE = 0
    nCS6 = 0
    nMWE0 = 0

    However nIOWR is always high.

    I have the same problem when trying to write to “Cylinder Low” and “Select Card/Head” registers.

    Any suggestions would be greatly appreciated.

    Thanks,
    Marc Lai
    paulc@logicpd.com
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    26 Sep 2007 04:23 PM
    i would recommend you look at the signals when you do a "mount fatfs /cf" in lolo to confirm that you know what the accesses are really supposed to look like. Also, make sure you are setting up the chip select in the Static Memory Controller otherwise it's won't be surprising if the external signals don't do anything for you.
    marclai
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    26 Sep 2007 05:22 PM
    Hi thanks for the response. That was a good suggestion. I had looked at the signals from the "mount fatfs /cf" command a couple months ago. However I still cant explain why nIOWR and nIORD do not strobe low. Can you tell me what input signals to the CPLD are used to generate nIOWR and nIORD? This would help me a lot in tracking my problem down. I have looked through all the discussion threads and the LH7A404-11 IO Controller Specification but can't find this information. I believe I am setting up the chip select correctly as nCS6 is strobing low.

    nMWR, CF_nCE, nCS6 and nMWE0 are the signals that I believe are important in generating nIOWR and appear to be strobing low at at the correct time but nIOWR does not strobe low. Are there any other signals I should be concerned with(besides the up_CPLD_CLK)?


    thanks again.
    kurtl@logicpd.com
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    26 Sep 2007 10:34 PM
    The nIOWR and nIORD signals will only assert low when nCS6 is low, the appropriate read/write signal is low, and an address between 0x60200000 to 0x603FFFFF is asserted.

    After power up, the Lolo "mount fatfs /cf" command will definitely assert the nIORD signal as Lolo must read data from the CF card in order to properly mount the device.

    -K
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