USB25IO in box For a long time I had wanted to interface a PC to the outside world, and so I have always kept an eye on eBay for data acquisition and general-purpose I/O cards. When in 2012 I saw the Mirrorbow USB25IO card selling at an excellent price, I could not resist buying one. This device is a small data input/output card that connects via USB to a computer. The image on the right shows it inside the small box I made to protect it. Its capabilities are configurable and are:

  • 24 Digital Input/outputs (three 8-bit ports) each individually programmed for direction
  • Up to 12 of the IOs may be configured as 10-bit ADC inputs (all 12 sampled with 1 command)
  • One 8-bit port can be turned into servo mode, providing control of up to 8 servos
  • An additional output provides programmable PWM (2.93KHz to 1MHz)

I was more interested in the ADCs than anything else, having worked in the past with nanosecond CAMAC ADCs made by LeCroy Corporation. The USB25IO devices are somewhat more modest, but still very interesting.

The first problem that I encountered was using the USB port to communicate with the USB25IO. Mirrorbow provided a Windows XP driver that emulates a serial port, and I started with that. However I wanted to write my applications in Java under NetBeans, and Sun have ceased support for serial ports under Windows. Fortunately there is a third-party library available called rxtx, and I was able to use that. This let me use it under both Windows and Linux.

Having tried a few simple things like cycling the LEDs that indicate the status of the first four bits on the USB25IO, it was time to do something more useful:

By the time I'd done all that, Mirrorbow had stopped marketing the USB25IO and I had upgraded to a different data acquisition device for my seismometer. However I'm always interested in new data acquisition projects so if you have a good idea for one,

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