Programming – Page 3

Accessing BT Home Hub 5 statistics with PHP + cURL

I’ve had the BT Home Hub 5 for a few months now, and it keeps restarting and generally acting like a cut-price pile o’ shite. So, in an effort to monitor its shitey-ness, I figured that my home server could extract the uptime and the traffic usage every x minutes.

Bt Home Hub 5A — A BT Home Hub 5A in its natural environment, with what looks like pubic hair in the carpet

The HH5 is – on paper – a great little router especially as it has an Infinity modem built in meaning you can do away with the separate OpenReach white box. You can’t mount it on the wall which is annoying, and the feet are fairly useless at keeping it from toppling over, but it does output both 2.4 and 5Ghz wireless networks. One of its big downside, at least for myself, is the lack of any way of scripted monitoring (e.g. SNMP).

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Making a radio controlled tank – Part 1 – Mechanics

I’ve tried my hand – literally – at quadcopters, submarines, and RC buggies, and now its time to make a tank. Hmmm, I guess more of a tracked box but we’ll call it a tank.

While searching for information on the subject, I ran across a website describing how he had made the treads out of bike chain and acrylic, the motors were ripped from cordless drills, and the chassis was essentially adult Meccano. All of this looks to be within the realm of possibility, and has the potential for being massively over-engineered – the best way to engineer.

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CRC8 – Arduino and PHP implementation

For my tank project, I’ll be sending parameters over radio to control the motors so the data packets should be checked to see if they’re valid or if the transmission was corrupted. This is a widely used concept in computing – almost every transaction comes with a checksum which lets you know whether the data that was sent is the same data that you received. If you’ve ever seen a cyclic redundancy check error on older versions of Windows, you’ve seen a bad checksum; the hard drive transmitted something that the operating system checked and found it wasn’t correct.

Data-Error-Cyclic-Redundancy-Check

EDIT

Looks like someone has beaten me to it, and created something much better. Here is an implementation which uses the built-in CRC module on the Teensy 3 to improve CRC calculation speed, and also creates 32 bit checksums.

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