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SD card hot plug error

julianjulian
edited April 2013 in Feature requests and bug reports
For your information, I stumbled over a stupid little mistake on the rev0.4 PCBs yesterday evening.
During the development I used 3 different SD cards and everything worked fine.
Yesterday I tried a newly aquired SD card from a different brand.

As it seems, when inserted during runtime,  the voltage drop caused by this new card is enough to cause a brown out error on the mainboard. :(
Booting with the card already inserted works like a charm.
An additional electrolytics cap between the 3V3 and GND rail on the frontpanel board fixed the issue. I used 100uF but probably 47uF is enough, I will try it out and let you know.

So if you experience problems with hotplugging your SD card, you may have to airwire an additional cap between 2 pins of the mainboard connector.

Will be fixed in the next batch of PCBs

Comments

  • dlylinedlyline
    An additional electrolytics cap between the 3V3 and GND rail on the frontpanel board fixed the issue. I used 100uF but probably 47uF is enough, I will try it out and let you know.

    So if you experience problems with hotplugging your SD card, you may have to airwire an additional cap between 2 pins of the mainboard connector.
    Where is it best to put this? Near the SD slot or psu?
  • julianjulian
    I've added mine to the frontpanel mainboard connector and it is working good.
    image
  • dlylinedlyline
    ok thanks for the pic  :-B thinking that's near the voice buttons?
  • julianjulian
    edited June 2013
    yes. above the open hihat/voice 7 button.
    the lower pin is GND and the upper pin is 3V3
  • dlylinedlyline
    hmm, i only had a 33uf/16v handy & it screwed up my lxr! do you have any idea what might have gone wrong?? my lcd was garbled & shift/copy leds plus some steps stayed lit.. needed to reupload firmware, really glad you have a bootloader julian  ;)
    i'll try again when i have a 100uf (soon)
  • julianjulian
    the cap should not screw up your unit regardless of its value!
    Are you sure you had the right polarity and the correct pins?

    A simple reeboot did not fix it?
    The new haven displays are a little bit picky about their cv's.
    even a simple reboot of the AVR during programming causes  these displays to show scrambled data :p
  • dlylinedlyline
    yes, it was connected as in your photo. i used multimeter to continuity check also..
    it didn't boot at all even once i removed the cap again!  :-<
    i am using a normal clcd.
    might have been the extra cold days we've had here??
    anyway working as normal after the hiccup 
    \:D/ 
  • dlylinedlyline
    working fine with 47uf/35v now
    :@)
  • julianjulian
    great :D
  • jannizjanniz
    I just recently get "SD Card init error" when turning on the LXR and can't load anything from the SD. It's still the same card I used right from the start – an old lady from one of my first digicams, 256 MB only – but it worked well since today. Do I have to reformat the card? 

    I didn't solder that buffer cap yet, because I thought I would not need to – since I "never change a running system". I already made a backup of the card so hopefully my patterns/sounds can be restored after all ..? Any idea what went wrong here?
  • dlylinedlyline
    maybe the sd socket has come loose? i only got the problem by removing card with LXR turned on..
    have you tried to read the card on a PC?
  • julianjulian
    things to check:
    4050 IC: sits tight in the socket, no cold solder joints
    all pins on the sd card socket on the mainboard attached firmly (should not move if you push them lightly with screwdriver or needle)

    the cap has nothing to do with this. without the cap the mainboard stops responding with some cards when you insert them while the synth is running. The "init error" indicates that the synth can't communicate with the card. so either the filesystem is damaged (then it should not work on the PC, too) or a connection came loose.
  • jannizjanniz
    edited July 2013
    I guess the filesystem somehow got corrupted ... When I removed the card I got "SD card not detected" so I thought the connections were all good. I was still able to read the card on either Mac/Windows, so I just copied all files to a new, freshly formatted card. Everything's fine again, all patterns/kits are still there :)

    I was blaming my Macbook for messing up the cards filesystem. I put the old card in my Mac yesterday to copy the new firmware onto it. OS X copies a lot of "invisible" files to every mounted volume so the Finder knows which windows were open and where and what size and whatever ... But they are only hidden on a Mac. I thought maybe these files might have confused the LXR. I erased all of them on a Windows machine today but the old card still doesn't work. So I still have no idea what happened but luckily everything could be restored. 

    Guess I'm gonna solder in the buffer cap anyways, since all of my ancient SD-cards cause the hotplugging-error. I just thought I'd never change the card while the machine is running ... but you never know.


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