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USB ports and the Saleae logic

I’ve been playing with a new Saleae Logic (8 channel version) on my Dell laptop. Had quite a few problems with the software locking up. I started moving the Logic between different USB ports, to find the Dell 14z has two types of USB ports. The Logic will not work with the two ports marked SS (for Super Speed part of the USB 3.0 architecture). The Logic runs fine on the USB 2.0 port. I don’t know where the problem is, but at least it works in the correct port.

For the money, the Saleae is an amazing piece of equipment. I would recommend buying from Amazon here. There appear to be a bunch of knockoffs being sold from China at much cheaper prices. The spelling of Saleae is odd enough that it is being forged.

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Software RAID 5 with SSD’s and IOPS performance

In an effort to eek more life out of my workstation, I decided to switch from a single mechanical disk to some on-sale Mushkin SSD’s. They were so cheap I decided to get three instead of one, and try software RAID. I’ve had previous experience with software RAID on Ubuntu, and been reasonable pleased with it.

For this upgrade I used three 120gb Mushkin Chronos units. I configured these on a Dell Precision T3500 (which despite its size, is hard to fit three drives into). This precision has a four core Xeon and 24gb RAM. It is old enough to only support sata 2. I installed Ubuntu 12.04 (alternate) and configured the three drives with software RAID 5.

Now the benchmarking: with iostat the previous 500gb WD mechanical drive would provide 70 to 100 IOPS depending on the size and duration of test. The new configuration provides 800 to 1000 IOPS at 4k size with random reads and writes. I do not have enough time to try with only RAID 0 or RAID 1, so treat this data anecdotal.

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Cheap solar panels and the SQFlex pump

I found a great deal on some solar panels on Amazon. They are sold by a company called DMSolar. The DM145 panels (145 watts) were sold for $160. If you have Amazon prime, you get killer two day shipping. Such a steal…if the panels are legitimate. Deals like this are often too good to be true. Upon receipt and inspection, the panels look clean and of good build quality. They are marked as being manufactured in Thailand…I wish I knew who really made them.

I hooked three panels up in series to run my SQFlex pump (ideally at 60VDC). The pump runs! At this point I do not have more than anecdotal evidence on the performance. I would guess I’m getting three to four gallons per minute. The watt meter on the pump’s control unit indicated 230 watts (out of a theoretical maximum of 435 watts)

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Solar mounts for the well house

I’m searching for the correct and cost-effective parts for the well-house. S-5 has been great in answering my questions. I settled on using the S-5-U Mini with PV Kit on Champion Snap-Loc raised seam roofing.

I found the clamp and PV Kit combo for $8.64 per piece (both pieces) at ABMartin. I was a little hesitant in using this company, but they had the items in stock, shipped quickly and gave me a reasonable shipping quote.

I also found the GBL-4-DBT grounding clamps at my local Platt. I was able to pick these up and not pay shipping.

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Model7 code now on github

I decided to put the code for this robotics journey on GitHub. Not really because I care to share it, but because I need a good way to bounce the code across two development machines onto the BeagleBone. Git is very easy to get working on Angstrom, subversion is not.

GitHub

Otherwise, it’s been a productive day. I wrote a python class to control the RoboClaw. I’m now sitting down to flush out some Arduino Mega stuff.

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Finally, Arduino to Beagle to RoboClaw is working

With a few tweaks I finally got the Arduino Mega to correctly talk to the BeagleBone. I gave up trying to get it to work over USB, and wired Serial 3 from the MEGA to UART4 on the BeagleBone. I can now get the ultrasonic distance measurements. This now allows me to complete a feedback loop between getting measurements and physically moving the robot. I took some video. I’ll get that processed eventually.

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Synology DS212J

I have held off buying a NAS for a few years. With the Gopro Hero2, I’m needing an amount of storage that is bordering on incredible. Finally broke down and get a Synology DS212J. It’s outfitted with two 2tb Seagate Barracuda drives.

This unit offers a lot of options. I got it to export a NFS mount so I can transfer files off my production Linux server. Using NFS, it seems to average 11MB/s transfer rate. I’ve enabled ssh and ftp. I’ve found ftp to be the best way to store backups from my linux machines.

The synology also has several apps you can enable, such as Plex and BitTorrent.