• From: Napa, CA USA
  • Registered: 2010-09-16
  • Posts: 100

Topic: sd image

I used the tutorial to create a 4g sd image.  I had no problems.  However, the new image takes significantly more time to boot up.  When powered on the Chumby sends the following:

0x8020a01d

and then waits about 15 seconds to proceed to booting up.  My question is: what's up with that?

I've used the rom image from chumby and I've used a direct copy from the original 1 gig sd using the "dd" command.  Same thing. 

The original sd boots up immediately, so I'm wondering if the size of the sd matters here, but I don't really know.

Is there a fix or do I have to live with the delay?

  • Registered: 2008-06-27
  • Posts: 518

Re: sd image

It could be that your new SD card is taking longer to go ready than the ROM is expecting.

That error apparently means that the ROM couldn't find the MBR, so it's halted booting.  The 15-second delay is it trying other boot devices, before it tries the SD card again.

There is a series of OTP fuses that controls how much time the ROM waits for the SD card, called SD_POWER_UP_DELAY.  Looking at the manual it's bits 19:14 of OTP fuse 0x18.  This is documented on page 7-26 of the reference manual.

The value defaults to 10ms, but can go all the way up to 630ms.  The bootloader contains commands to muck around with the OTP fuses, and blow some of them.  It may help to increase the delay.

  • Registered: 2010-10-09
  • Posts: 16

Re: sd image

ChumbyLurker wrote:

... This is documented on page 7-26 of the reference manual.

What!?  What is this manual?

  • Duane
  • Duane
  • Blue Octy
  • Offline
  • From: San Diego, CA
  • Registered: 2006-08-24
  • Posts: 8,197

Re: sd image

amiso wrote:

What!?  What is this manual?

There are a couple manuals linked from here including the CPU reference manual.

Duane's Website