Another Mouse issue with Indivision ECS

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Don't Panic. Please wash hands.

    Hi,


    With the Ind. ECS installed in my A500 I get some random mouse movement when the mouse is unplugged.

    When the mouse is plugged in I can only move the mouse Up and Left.


    I had already replaced the U15 multiplexer before I realized it was happening only when the Ind. ECS was installed.

    I have tried installing a 1.2k resistor between Denise pins 9 &19 as I read on another thread.

    This eliminates the random movement but I still cannot move Down or Right.


    The voltages at the U15 multiplexer suggest that the Down & Right signals from the mouse do not go from 5V to 0V - the only reduce to 2.5V.


    I saw a suggestion to replace the 74LS157 multiplexer with a HC or HCT type.

    Could that change help with my direction issue, or is it really only for the random movement that is already eliminated by the pull up resistor?


    Thanks!

    Quote from Wavey78

    I saw a suggestion to replace the 74LS157 multiplexer with a HC or HCT type.

    Yes, please do that. The old LS types that you find "somewhere on the net" these days have highly questionable characteristics.


    HCT type would be preferred, but HC will also work.


    Jens

    Thank you for the reply.

    Do any of theses HCT units look suitable?

    https://ie.farnell.com/c/semiconductors-ics/logic?st=74hct157&showResults=true


    Im not sure how significant the letters at the end are?

    THe letters at the end usually show the package and temperature range, possibly green status and additional qualifications (automotive, industrial or so - you'll only need "commercial"). You can't go wrong with TI, so SN74HCT157N would be a good part.


    Jens

    Hi Jens,

    I have installed the TI chip but unfortunately the problem remains -also with the pull resistor in circuit.


    Can you advise what I can do here?

    I read on the forums somewhere that the mouse issues came with a change to the card at some point.

    Is there an option to roll back the firmware?


    Also just to check, my unit does not have a socket on top to piggyback the Denise chip so the Denise chip is completely removed. I have seen some cases where there the Denise is inserted on top the ECS unit. Do I have the correct untit for my A500?


    Thanks!

    Quote from Wavey78

    Is there an option to roll back the firmware?

    I suggest to ONLY use the latest firmware. Launch the latest config tool and flash the firmware (menu item in drop-down menu). Depending on when you've bought it (or if you have even bought it used), you may have an old firmware that has the issues you're describing.

    Quote from Wavey78

    Also just to check, my unit does not have a socket on top to piggyback the Denise chip so the Denise chip is completely removed. I have seen some cases where there the Denise is inserted on top the ECS unit. Do I have the correct untit for my A500?

    Only Indivision ECS V1 has the option to put a Denise chip into it. The newer V2 and V3 units completely replace the Denise chip. Please run the config tool for V2 (which also covers V3), and run the firmware update.


    Jens

    It's very well possible that you've received a unit that went through QC before an update. We don't unpack all stock and re-flash when there's an update, unless it's a no-go situation that needs to be resolved with such an update.


    So just download the latest config tool and run the firmware update - can't go wrong with that.


    Jens

    Hi Jens,

    Quote from Jens

    It's very well possible that you've received a unit that went through QC before an update. We don't unpack all stock and re-flash when there's an update, unless it's a no-go situation that needs to be resolved with such an update.


    So just download the latest config tool and run the firmware update - can't go wrong with that.


    Jens


    I have flashed the firmware but no change.

    What to do now?

    Since the pull-up resistors did make a change in your setup, you could add pull-up resistors to all four multiplexer-output lines. So far, I believe you've only installed two, tight? If so, please take a picture of what you've added, and I'll see where the other two can go.


    Jens

    When I read "two resistors", I thought you had put pull-ups to two signals, but this is only a quarter of the mod that I'd suggest if you want to try pull-ups.


    Special service: I have used wired resistors to do this exact mod, using the 1.2k resistor value that you've found in some other thread (not sure where I've mentioned that, but it might have been someone else). If you suspect that the signal quality from the muxer isn't good enough, you need to go all the way and pull up all four signals. BTW, there is no "up" or "down" signal, nut a pair forms a quadrature signal that pulses "up" or "down", so on a "left" or "right" movement, both horizontal signals are involved, no matter what direction you're going. Same with the vertical signals.



    Not sure if this will really make a difference, as the 74HCT part should have way better signal integrity. You might have an additional problem in that particular computer, but this is worth a try.


    Jens