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Hello Amit,

Are you powering the BeagleBoard from the external 5V power supply? If so, try instead powering it via the OTG USB port. This is the small USB port. Disconnect the 5V power supply.

I found that for the C4 revision BB the I2C only works when the board is powered from the OTG USB - not the 5V power supply.

Best regards,

Pascal

Hi Pascal,

I am using the 5v power supply. However, I found that when I try to power it using OTG, the angstrom demo image does not load. In between, it gives an error (here is the copy of tera term pro)

21.125762] [<c004c2e4>] (omap3_pm_idle+0x4c/0x50) from [<c0625fd0>] (0xc0625fd0)
[   21.133270] Code: e3530003 13a02000 05963078 05933018 (05d33014)
[   21.139465] ---[ end trace 8ab6a661b2f156b8 ]---
[   21.144134] Kernel panic - not syncing: Fatal exception in interrupt

If I power it using 5V supply, everything goes smoothly and the login screen comes up. 

I have a windows xp machine and I am connecting a USB to mini-usb cable from my PC to beagleboard OTG port to power it up

Amit

Amit,

I have not tried the latest Angstrom Demo, so I can't say why it is giving a kernel panic when powered from the OTG USB port. TI did not develop the Angstrom Demo, and can not support it. I suggest that you post the kernel error issue to the Angstrom support forum and see if anyone there can give some help.

However, I have confirmed several ways that the i2c-bus3 commands do not work if the BB is powered by the 5V supply. The i2c-bus3 commands do work if the BB is powered by the OTG USB port. The i2c-bus3 commands also require root privileges, so you must be "root" or use the "sudo" command if you are logged in as a normal user. Angstrom allows you to log in as "root", but some other Linux distributions restrict login as root, requiring a user login.

I am using an Ubuntu installation on the BB, which is working. But, it is not an off-the-shelf installation. It required quite a bit of tweaking.

I will continue to look into this - but meanwhile it would be good to get some help from the Angstrom users.

Pascal

Pascal,

There is no good reason that I2C should only work when powered via OTG USB per the BeagleBoard itself.  Perhaps you can share more information on your configuration?  I suspect you might have some sort of grounding issue here where the ground for the Pico Projector and the ground for the BeagleBoard aren't the same.  They need to share good grounding for I2C to work properly.

Regards,
Jason
(co-founder of BeagleBoard.org)

amit agrawal

Hi Pascal,

I am using the 5v power supply. However, I found that when I try to power it using OTG, the angstrom demo image does not load. In between, it gives an error (here is the copy of tera term pro)

21.125762] [<c004c2e4>] (omap3_pm_idle+0x4c/0x50) from [<c0625fd0>] (0xc0625fd0)
[   21.133270] Code: e3530003 13a02000 05963078 05933018 (05d33014)
[   21.139465] ---[ end trace 8ab6a661b2f156b8 ]---
[   21.144134] Kernel panic - not syncing: Fatal exception in interrupt

If I power it using 5V supply, everything goes smoothly and the login screen comes up. 

I have a windows xp machine and I am connecting a USB to mini-usb cable from my PC to beagleboard OTG port to power it up

Amit

You need to use a Y-cable when powering the BeagleBoard from a USB port, per the BBSRM_latest.pdf document.  One of the Angstrom maintainers (Koen Kooi, currently also doing some contract work for TI) has also provided a kernel build that lowers the power consumption to make it more likely to work off of OTG power.  It also compiles in the Gadget Ethernet driver to avoid producing a kernel fault due to an unplugged interrupt handler when the PC tries to start talking to the BeagleBoard.

Look in http://www.angstrom-distribution.org/demo/beagleboard/ for uImage-2.6.32-r88+gitra6bad4464f985fdd3bed72e1b82dcbfc004d7869-beagleboard.multi-config-cpuidle-gether.bin

You can read a bit more about this on the BeagleBoard.org discussion group list as it relates to enabling cpuidle and also on the IRC logs.  We were also discussing this on the IRC channel today.

You might also find http://www.flickr.com/photos/koenkooi/4941801167/ interesting as it is a configuration that avoids grounding problems.

Hi Pascal,

I also tried ubuntu lucid 10.04 on the beagleboard. Unfortunately it does not have bus3-i2c capability and the build does not have gcc for me to compile i2c-tools on the beagleboard.

Is it possible for me to try your ubuntu image if you can upload it somewhere?

thanks

Amit

Hi,

I got the I2C working with the power via OTG!!. But it does NOT work with the 5v supply. Now I can run picodlp-control and bus3-i2c commands. Jason, you might want to look into it further,

I am running the latest Angstrom demo image on beagleboard C4 using a SD card.

Amit

Amit, Pascal, Jason and others, I just wanted to confirm that my beagleboard showed the same behavior -

when I was power the board using the external 5V supply, the bus3-i2c commands failed:

ERROR: I2cTransfer: ioctl failed: Input/output error (5)

ERROR: I2cReadByte failed: -1

However, the commands do work when I power using the USB-OTG port and a Y-cable.

So this thread was very helpful for me. Thanks.

hi,

where can I get  picodlp-control and bus3-i2c commands?