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SD Card Preventing Propeller from Booting — Parallax Forums

SD Card Preventing Propeller from Booting

ZenexerZenexer Posts: 20
edited 2011-09-03 17:20 in Propeller 1
If I have a microSD card wired to the Propeller starting at pin 1 (not 0--haven't tested that), the Propeller appears not to boot. I can flash RAM and EEPROM just fine, but my program, which normally outputs data to a serial terminal, leaves my screen blank. The moment I remove the SD card and reboot, things go back to normal. Any ideas?

If I simply remove power to the microSD card and leave all the other pins connected, the Propeller boots fine.

If I insert the microSD card during runtime, the Propeller freezes execution.

Comments

  • ZenexerZenexer Posts: 20
    edited 2011-09-01 09:42
    I tried removing power from the SD card. That allows the propeller to boot, but of course makes the SD card unusable.
  • rokickirokicki Posts: 1,000
    edited 2011-09-01 09:44
    Time to check your wiring. There's no way an SD card wired to pin 1 should be able to
    prevent the prop from booting.
  • Mike GreenMike Green Posts: 23,101
    edited 2011-09-01 09:45
    You probably have the SD card socket wired wrong or the SD card socket is defective. When you insert the SD card, the power supply is short circuited. There is no other way an SD card could prevent the Propeller from booting.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-09-01 09:51
    Since you're able to program the Propeller with the SD card in its socket, I doubt that it's causing any actual shorts in the power supply. The difference is that, when programming, the Propeller is running in RC mode, not with the crystal. What kind of power supply are you using? What kind of capacitive filtering and bypassing have you implemented?

    -Phil
  • ZenexerZenexer Posts: 20
    edited 2011-09-01 11:18
    Thanks for the help, Phil. It turned out to be an unnecessary capacitor that I was using based on the demo board schematic. All I had to do was yank it.
  • rokickirokicki Posts: 1,000
    edited 2011-09-01 13:30
    Zenexer wrote: »
    Thanks for the help, Phil. It turned out to be an unnecessary capacitor that I was using based on the demo board schematic. All I had to do was yank it.

    Can you tell us more? It would be a very unusual problem if removing an extra capacitor fixed it.

    Usually extra capacitors help, rather than hurt.

    Your problem might be some edge condition somewhere and there may be many small changes
    that "fix" it---none of which actually are the real solution.

    What type and size was the capacitor, and what was it connected to?
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-09-01 13:36
    I agree with rokicki. The premise of my question was a suspicion that you didn't have enough of the right kind of capacitors in your circuit.

    -Phil
  • ZenexerZenexer Posts: 20
    edited 2011-09-03 15:39
    I had a 1 uF capacitor crossing from Vdd to Vss.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-09-03 16:11
    That should definitely not have caused a problem. What kind of capacitors do you have now between Vdd and Vss?

    -Phil
  • ZenexerZenexer Posts: 20
    edited 2011-09-03 16:43
    Simply one 10 uF. Before I had two 1 uF capacitors (I thought one was a 10 uF capacitor).
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-09-03 17:20
    You also need bypass caps, in addition to your 10 uF filter cap. Ideally, one 0.1uF ceramic cap would be connected to each Vdd/Vss terminal pair of the Propeller chip right next to the chip. That's two caps for the DIP; four, for the other packages. Bypass caps are not optional; they're required. Without them, you can actually cause permanent harm to the Propeller's PLL circuitry.

    -Phil
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