Week 3 – Struggling with Beagleboard

My goal this week was to set up my Beagleboard as a RAID server. I have had a Dell system with 2 external USB disk drives set up as RAID 1 as my server for the past few years and it has served me well but I don’t like the idea of leaving it powered on all the time as I am pretty anal about watching my power usage. I decided to set up the Beagleboard as my server for two reason: 1. less power – the entire system with disks is less than 10 watts. 2. I will soon be getting a Raspberry Pi and the Beagleboard will no longer be of interest as a development platform.

Well, this week turned into a massively frustrating exerience with the Beagleboard trying to get Linux running. I continue to see errors with the MMC card no matter what I do. I am trying to use a Ubuntu arm build and if I use either the curent 11.10  or 11.04  releases I see a boat load of these errors:

[  181.645996] mmcblk0: error -84 transferring data, sector 4603160, nr 32, cmd response 0x900, card status 0xb00
[  181.735992] mmcblk0: error -84 transferring data, sector 4604216, nr 136, cmd response 0x900, card status 0xb00

If I go back to 10.10, I see a similar boat, but it is full of these errors:

[   20.931884] end_request: I/O error, dev mtdblock2, sector 8
[   20.944763] uncorrectable error :
[   20.948272] end_request: I/O error, dev mtdblock2, sector 128
[   20.961456] uncorrectable error :

I have tried several different SD cards and it acts the same so I am guessing there is some issue with the MMC drivers in the linux kernel for ARM.  The lack of people complaining about this when I google it gives me a bit of suspicion about this but the fact that it acts differently under different Linux kernels make me think that there is something fishy going on.

So here is my plan. I am going to spend another week on this project. First I will try the Ångström distribution for the Beagleboard and see if the MMC errors persist. If not, great, I can get the RAID services running and perhaps take on my next project. If the errors persist, I’ll dig into the kernel sources and see if I can do anything about it. I don’t have access to an ARM emulator, so I will just be able to look at the code and MMC specs to see if I can determine what is going on and fix it. I plan to either have this working by next Sunday, or I simply give up and buy an extra Raspberry Pi board for the server.  Even if this turns into a two week failure, I’ll have learned some stuff about the Linux kernel and MMC protocols.

I also started my oximeter project. I took apart a commercial oximeter that I bought to see what makes it tick. I’ll post pictures as I dig into the project more.

Also, I got a pad lock open that I don’t know the combination to using a coke can (look here).


So this week I finished just under the wire. I made a sign out of EL wire to take to Buffalo Bandits games so that when the opposing team get a penalty, I can celebrate with some geeky flair. Here is the result:

B-O-X finished (click on this to watch the video)

Most of the work on this was attaching the EL wire to the piece of carpet that I bought at Home Depot. I did the layout in chalk and then attached the EL wire by stitching it with embroidery floss. This took several hours as I am not so skilled at hand stitching.  I then wired the EL wire to a cat-5 network cable which was used to power the lights.  This attaches to a box that has a 3 AA batteries, three AC inverters to power the EL wire and 3 switches (OK so it has four switches but one isn’t used because I had the crazy idea that I could light all three just by wiring another switch an powering all three. luckily I drew out the wiring diagram right before I started soldering and realized my blunder)(UPDATE 23Jan2012-16:14: So I realized in the shower this morning that I just need some diodes to allow the 4th switch to turn on all three letters in a way that doesn’t affect the other switches, I’ll update the circuit and post the schematic at some point).

I still need to wash off the chalk and cover the curly turns but I am calling it done and I will take care of these cosmetic things when I go to the Bandits game (I can’t make the game this week but I’ll be there on Feb 4).

Here are some pictures.



Alright so I’ve got a blog now

I’ve decided to take up the challenge and make a thing a week (or at least make really good progress on whatever it is that I am currently working on).  I need to figure out wordpress a bit to make it work for me and then I am going to get started. Also I don’t know what I want to used for and idea notebook, I’m not sure if WordPress is what I want or a wiki or something else.

Here are the ideas that I have on the ready. I should add that there are two quite distinct categories that I’ll be following – tech and cooking. I doubt that they’ll intersect at all unless I end up getting into sous-vide, which I doubt will happen.

The Tech stuff looks like this right now:

  • B-O-X  I want to make a cool lit up B-O-X for taking to Bandits Games (indoor lacrosse) to get into the fun when there is a penalty. I have two ideas at this point.
    1. Using EL wire and some sort of reasonably durable structure but yet not too difficult to carry and deal with at a game that will hole the wire so that it it the outline or B-O-X with switched to turn them on at the appropriate time.
    2. Having a longing pole with a bunch of bright LEDs and do a POV B-O-X. This would need some small processing (arduino or maybe MSP430) and something to drive the LEDs. I’m not sure if it would need to drive directly or use I2C or SPI or something. I’ll need to look at the speed require to do the POV.
  • Get the GigaPan out of the box and use it and make some amazing pictures. I am thinking a nice picture of Occupy Buffalo could be really cool if I found the proper vantage point for taking the picture. Once I figure it out there are bunches of possibilities.
  • Get idverbhernoun.com going. I’ve go the domain name and the idea. I just need to figure out enough about web stuff to find or build the code. I think it might be fun.
  • Look into Android-Arduino using the ADK that Google put out last year.  I have a bit of a start on this but I need to think of a cool application to make it real. Maybe the POV B-O-X think might be the right app.
  • HexBright – once I get it and figure out how to control the PWM I think some fun will be had. I’m not sure if it is bright enough to make a decent strobe of photo flash, we’ll see. Also some modulated light communication might be fun.
  • Raspberry Pi – I want to get one and get to know it and use it for everything I can think of.
  • Solder up the Pico Paso boards that I bought to give to my friends.
  • Build a pulse oximeter. This will be a bit of a bigger project.  I may break it into parts. Making a decent finger dealy (fingermajigger) with the LEDs and light sensor might be one part. Gathering data to measure the SaO2 level accurately might be another piece and then getting it all together and packaged and documented as sort of a finished product could be another. I’d like to see if I could write an article for make or something about this.

Food things (this list will grow):

  • Bake Pies – Pie Crust is a thing that intimidates me and I am just going to have to get over it and bake some pies.
  • Paneer – This will be fun but might smell bad if I don’t do it right.
  • Pierogis – I’m Polish and should be able to make these in my sleep. I want to get tot he point where whipping out some flour, eggs and farmers cheese is second nature.