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LINUX DRIVES WEEDER I/O BOARDS

by Jack Dennon

Start ý Create the Device Driver ý Create the Device ý The Order of Things ý Load the Device Driver ý Call the Test Program ý Remove the Device Driver ý Sources and PDF

Weeder Technology makes a series of I/O boards that can be plugged into the serial port of a PC to provide low-cost data acquisition and process control. The boards are addressable in such a fashion that up to 32 of these boards can be connected in series to a single RS-232 computer port. Boards that provide functions such as digital I/O, analog input, analog output, stepper motor control, and a counter/timer are available. Also available is a board for connecting and addressing a third-party RS-232 device.

When you attempt to use a product in the real world, unanticipated requirements inevitably arise. These are handled most easily when you have total control of things. Datasheets that come with the boards include QuickBASIC software that can be used to access the boards under DOS. In this article, Iýll show you how to develop functionally equivalent software that can be used to access the Weeder Technology I/O boards via user software written in C and running under Linux. Using an open-source OS such as Linux along with a simple homegrown device driver gives you the level of control you need.

The device driver developed here can be used with any of the Weeder boards. Also, a sample user-side test program is included that demonstrates how to use the device driver. The test program reads 14 bits of data from a Weeder Technology digital I/O board, WTDIOM.

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