Introduction

Introduction

Measurement and control applications of digital computers usually require sensors with analogue signals and digitizing electronics at the computer/sensor interface. The analogue output of sensors are digitized by Analogue-to-Digital conversion (ADC) techniques. This digitized signal can then be:

manipulated mathematically,

stored (in digital memory),

displayed or used to make decisions.

For control applications, often the converse is needed. A digital signal emanating from a computer must be used to control say a machine. So it must be transformed into an analogue signal. This is usually by a Digital-to-Analogue converter or DAC.

In some control applications counting and timing of events are also needed. Nowadays most ADCs and DACs are monolithic integrated circuits much the same as say a memory or microprocessor integrated circuit (IC).

For ADC ICs the major properties of interest are:-

conversion time :-this should be faster than the response time of the sensor'

resolution:-modern 12bit to 24 bit ADC's (with 3-5 volt full scale deflection) suits many sensors whose outputs are often buffered by high impedance op amps with appropriate gain. Recently sub-microvolt sensitivity is commonplace with state-of-the-art converters.

Linearity.

For DAC IC’s the important properties are:

settling time

and slew rate so that the analogue signal can follow as close as possible the digital one.

PCI ADC/ DAC implementation generally requires

good analogue circuit practice;

implementation of a PCI bus Master,

some programming,

some sensor signal conditioning.

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Linux drivers for modern PCI DAQ cards

In modern applications, most analogue data acquisition cards are PCI-based. Generally these are

Analogue to digital conversion (or ADC cards)

Digital to analogue or DAC cards

Cards with Counter/Timer circuits for timing and counting events

Digital I/O cards

Multifunction data acquisition (DAQ) cards (cards with ADC, DAC , counter/timer etc).

Now the interfacing to the PC-bus of many modern DAQ cards invariably means programming a PCI bus-mastering ASICs such as the AMCC5933, the PLX9080 and ASICs by Vcubed and others. This program is primarily the device driver. However Linux Device drivers for such DAQ cards are relatively under -developed for the most modern PCI cards. This is due to a combination of factors below

Lack of in-house Linux programming expertise in many card and ASIC manufacturers
The clash of the the open-source with Non-disclosure agreement in which some card manufacturers may have entered into with proprietary 'software interests';.

This project aims to help the development of such drivers in selected cases. On the left column are links to sites offering guidance in device driver programming on Linux. To find out more and to participate in our device driver program, please click on "PCI busmaster driver" near the top in the left hand column.

Common DAQ Card types:

PCI 9112, PCI9118, PCI9812 using the AMCC 5933 ASIC
PCI9111, PCI9114 et al using the PLX 9080 ASIC

Comprehensive description, prices and availability of these cards are given by Basis Volume Limited.

Downloads:

Only Downloads for Adlink cards yet available

Basis Volume Limited supply cards using these drivers and our training group runs embedded Linux training courses which include driver development for cards of this type. Thus additional data sheets for the above cards are available from our training-site.

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