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by wknight
Tue Jul 10, 2012 5:05 am
Forum: Troubleshooting
Topic: Raspberry Pi does not boot
Replies: 4
Views: 2651

Re: Raspberry Pi does not boot

Hi, I have tried the instructions on http://elinux.org/RPi_Easy_SD_Card_Setup (Copying the image to an SD Card on Windows and Copying the image to an SD Card on Windows if first option isn't successful), on 2 SD cards but my raspberry pi does not boot. I only have the red light for PWR on, non of t...
by wknight
Sun Jul 08, 2012 8:45 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

The GPIO's of the Broadcom's SoC (the SD-Card is connected through GPIO's with dedicated SD-card logic behind them) are capable of several "tricks", one of them is that they can enable a pullup (or pulldown) resistor on GPIO's programmed as inputs, in fact its possibly possible to select either a "...
by wknight
Sun Jul 08, 2012 5:39 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

Do you have an sdcard that fails with latest bootcode without the pullups, but works with them? If so what is the state of OK LED? I am sorry but I can't check it now because it is not so easy to desolder the resisters. May be somebody else who didn't solder it can help us. thanks for your answers
by wknight
Sun Jul 08, 2012 3:07 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

Yes an update to bootcode.bin on June 22nd added pullups to the sdcard. I'd be interested if you believe the pullups are still necessary on any sdcards with the updated bootcode.bin. As I understand CPU can read bootcode.bin only after first SD card initialization. Is there some small code inside t...
by wknight
Sun Jul 08, 2012 1:53 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

dom wrote: The latest official image doesn't have the software pullup fix to bootcode.bin. It's only available from github or by using rpi-update.
By the way if you don't have a "compatible" SD card. It is hard to start.
Am I right ?
by wknight
Sun Jul 08, 2012 1:44 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

Yes an update to bootcode.bin on June 22nd added pullups to the sdcard. I'd be interested if you believe the pullups are still necessary on any sdcards with the updated bootcode.bin. I only know. I have took all my SD card from all my electronics to test it (mobile phone, photo camera , portable pl...
by wknight
Sun Jul 08, 2012 1:39 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

Pullups stop the inputs to digital circuits waving abut in the wind due to electrical noise. It is true if the resistance of the pullups is equal to wave impedance of the line. In our case the value of pullups is much higher. The reason is different. Doesn't one of the latest updates to the firmwar...
by wknight
Sun Jul 08, 2012 1:08 pm
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Re: Now my raspberry pi works with all my SD cards

Steep wrote:What does this do exactly?
In transcend datasheet it is written "To prevent bus floating".
I think it helps to detect the type of the card.
There is the period of time during configuration sequence of SD card,
then some pins of SD card and the controller are configured like inputs.
by wknight
Sun Jul 08, 2012 7:09 am
Forum: Troubleshooting
Topic: Now my raspberry pi works with all my SD cards
Replies: 19
Views: 3642

Now my raspberry pi works with all my SD cards

Hi
May be it will help you.

I have found only one SD card which works perfectly (I have tried 5 cards).
It is not necessary to search compatible SD card for raspberry pi.
It is much easy to solder pull-ups resistors 10k-100k on SD connector pins 1,2,7,8,9.
There is power supply +3.3V on pin 4.

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