ACA1221EC (and minor ACA500plus) RTC issues?

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Don't Panic. Please wash hands.

    Hey there,


    A couple of years ago I purchased a second hand ACA1221EC accelerator for my A1200.


    The board seems to be working flawlessly, except maybe the RTC port.


    I'm adding "maybe" since I'm using a (well known?) public domain RTC expansion plus a flat cable since it won't fit otherwise. The RTC expansion does work when installed on the dedicated ACA500 plus port though, even though it often won't be recognized at boot (it seems launching the ACA flash utility somehow "wakes it up" but I have no idea how this could be possibly related), despite being forced on the relevant setup page.


    So the question is: how do I check if the ACA1221ec has an actually working RTC clock port? Could the flat cable (roughly 20cm long) be the issue preventing it from being recognized?


    By the way when I checked the ACA1221ec board on the A500 (via ACA500plus) I forced the RTC to "A1200 accel."

    I would happily try that but I can't: as I said it won't physically fit otherwise. And I understand the second RTC port of the 1221 has a different address so it can't be used as a backup solution.

    Ok I really feel dumb. It's definitely an issue due to the flat, I can't be 100% sure the ACA1221 clock port is working but it's very likely the cable since it's mirroring the connection. Damn, how did I miss that?!

    Pinout mirrored, but no magic smoke coming out? That sounds like you've won the "double fault limits damage" lottery, as pin#40 of the clock port is not connected anywhere. This is where the 5V pin comes in on a mirrored-and-reversed-at-the-same-time connection.


    If it was only mirrored, then the two GND connections would have shorted 5V and GND, making the cable a heater coil.

    Yup everything seems to be working fine.


    I guess I learned a lesson anyway despite (apparently) no damage done, I'll be WAY more careful and doublecheck everything as soon as I have the next RTC board assembled, with the proper (male) connector this time.

    I can confirm the RTC (now with a proper male connector) works perfectly fine with a 20cm flat cable, with both the A1200 internal clock port and the ACA1221 one.


    Marking thread as resolved.

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.

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