Thursday, October 29, 2015

Happy 46th Birthday, Internet!

46 years ago today was the first remote transmission between two computers using TCP/IP. You have come a long way baby!

In the glow of a green monochrome screen deep in the bowels of the computer science department at UCLA, a young graduate student (Charley Kline) picked up his phone and called the computer lab at Stanford. He is preparing to send the first message over an Internet connection. The men on either end of the phone are Charley Kline and Bill Duvall.

Thank you Leonard Kleinrock, Charley Kline and Bill Duvall, it was the start of a beautiful friendship. 

Wednesday, October 28, 2015

Add up to 128 Inputs, Outputs, or a mix to your Arduino or Raspberry Pi

The MCP23017 is a very useful chip. This I2C device can be wired for 8 unique addresses, and offers 16 inputs, 16 outputs, or 8 of each. A one stop chip for all needs.

You can talk directly to the chip, or use widely available libraries to insulate your experience from the nitty gritty.

Tronixstuff has a fantastic Arduino tutorial which covers a non library implementation. Very easy to understand, you may wish to avoid a library altogether.

Adafruit has a great Raspberry Pi tutorial to get you up to speed with a great increase in I/O capability, as well as allowing 5v I/O where the Raspberry Pi would only accept 3v inputs.

These can be used to convert a parallel lcd to I2C, and give button inputs as well. Adafruit makes a lcd button shield using this functionality. Build your own at

Drive this 16 channel relay board -

Sunday, October 25, 2015

Arduino Ethernet Cable Tester

As a network engineer, I never go anywhere without my Ethernet cable tester. That and a audible cable finder (fox & hound) are invaluable for finding and testing cable pairs. Today I'm showcasing a Arduino Ethernet cable tester. This tester is switchable for a straight through or crossover test. Test results are seen in a ordered line of LED's, as well as serial output that could be displayed on a LCD and written to a sd card.

A Arduino fox and hound will come  later, and then maybe a TDR distance to fault tester. We will see.

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