Linux Hardware Access
All programs on this page are free under terms of the GPL.
AD-DA CONVERSION WITH R-2R NETWORK
I have done some experiments with simple AD and DA convertors connected to the parallel port of my computer.
The DA-convertor is of the so called R-2R type and consists of 10 k and 20 k resistors (see diagram below).
The output of the DA-convertor is buffered with an opamp. Another opamp is used as a comparator and compares the output of the DA-convertor with the analog input signal. The software uses the method of successive approximation to calculate the input 8-bit value of the input signal.
The software package contains a DA and an AD conversion program (using xforms of course).
N.B. because of the multitasking nature of Linux this DA / AD convertor is rather slow. I.e. when reading in values from de AD-convertor there can be delays of 10 or more milliseconds. So use this stuff only for slow varying signals.
This programs is derived from an original program to control a Kenwood transceiver.
That program was written by Jeff Pierce (WD4NMQ).
Jeff did all the hard work. I only changed the software to access te ICOM transceiver, because the protocol used is totaly different from the one used by Kenwood. I also changed the way pixmaps are used, so this program can be started by doubleclicking in the icon in filemanager. I have included a diagram with information how to connect the Icom radio to the serial port.
See the documentation in the package for using the program with other radios.
N.B. the software uses the serial port to talk to the radio, so if you want to use the serial port for another piece of hardware, take a look at how this program works.