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Showing posts from November, 2008

Does Google blur phone numbers on Street View?

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I was looking for a business telephone of a tyre repair garage. Unfortunately the small shop might not be paying to get an ad on yellow pages and I could not find it. Next step was to try to find it on Google Maps Street View, as I knew there were lots of text on the garage walls. Unfortunately, though I could find that street photos, the photos blurred the last group of seven numbers. Though I've searched around, it does not seem to be an error: Apparentely the software does blur not only faces but also license plates. I wonder wheter these numbers on the wall might be considered license plate numbers. At any rate I was lucky enoughthat one of the angles of the scene did not blur the numbers. Hopefully we'll get an appointment to get our punctured tyre repaired soon.

Some power benchmarks

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After some time willing to do this I've found a moment to do some measurements. Firstly, I've removed Arduino Mini Pro power led resistor to see how much current was needed for the device in power-down mode: It's just 155uA@3V3, even lower if you go down to just 3Volts. The Mini needed 5mA for normal operation (with no output loaded). The other component I was interested on testing together was Digi's XBee module. While XBee needs 50mA on operation, using SM=1 (Hibernate mode) the power goes down to 1.6uA when sleep mode is forced (by raising pin 9 to high). That all means that a basic wireless sensor node based on this components will use at least 55mA during ON periods and 0.16mA while SLEEP. That translates into about 4 hours of continuous operation from a 220mAh 3V button cell. However, if node is powered up only 3 seconds every 5 minutes, then the same battery should last around 13 days. This seems to start looking ok for my sensor network project.
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A recent project required the use of an industrial computer, able to work within a wide range of temperatures. Interaction with other systems would happen by serial and Ethernet ports. I've used devices manufactured by Moxa , running uClinux (a slim version of Linux that can run in systems without an MMU, like some ARM processors). Development is done using a GNU C cross-compiler and almost all the time development uses familiar tools. My systems came from factory with an old version of the kernel I had to upgrade, but once upgraded they are working rock solid. Manufacturer support was also valuable whenever a feature was expected but missing on the uClinux distribution (i.e. no ?time functions on busybox-based find).