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Eagle PCI30 Analogue Input Example

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This example shows how MATLAB's Generic DLL Interface Functions allow you to interact with an Eagle PC30 device and acquire analogue data. Only a single buffer of data is acquired in this example. It is beneficial to be familiar with MATLAB's Generic DLL Interface Functions and the PC30's DLL methods for this example.

This code 'runs' but due to the lack of a terminal board we don't know if it actually 'works'! Any feedback/ enhancements to the code presented here would be welcomed.

Contents

 

Getting More Information

More information about interfacing with .DLLs from MATLAB can be found in MATLAB 7.0's HTML documentation contents at:

MATLAB/External Interfaces Reference/Generic DLL Interface
Functions

Pointers are required when setting up the various device properties. The LIBPOINTER function is used to create these pointers in MATLAB, for more information type:

doc libpointer

at the MATLAB command line. See the PCI30 device driver manual for more information on the devices .dll calls. This should be downloadable from Eagle's website: http://www.eagle.co.za.

Loading the Dynamic Link Library into MATLAB

In order to call methods belonging to the device driver we need to load the .DLL into MATLAB. We use the LOADLIBRARY function to load the functions defined in header file 'EDRAPI.H' and found in shared library 'edrapi.dll' into MATLAB. The LIBFUNCTIONS function is useful for seeing the names of the library functions available.

% Load the driver .dll
loadlibrary ('c:\WINDOWS\system32\edrapi.dll', ...
'C:\Prog\Eagle\include\EDRAPI.H');

% Find the methods offered by the .dll
m = libfunctions('edrapi', '-full')

Error using ==> loadlibrary>lFullPath
Could not find file C:\Prog\Eagle\include\EDRAPI.H.

Creating a Buffer Variable to Store Acquired Data

When the device starts acquiring data we need to have somewhere in memory to store this data. The .DLL's methods require a pointer to this memory location, which is created in this section.

% Get the maximum number of samples we can store

% swBufferSize = calllib('edrapi','EDRE_Query', ...
% deviceSerialNumber, 106, 0);
% 1048576 apparently
swBufferSize = 1000000; % 1048576 gave issues so hardcoded
% for the time being

% NOTE: The variable 'inputDataBuffer' just contains the
% values with which the memory pointed to by 'buffPointer'
% is initialised. The variable 'inputDataBuffer' is not
% actually the buffer into which the data is put (the data
% is actually put into the memory pointed to by 'buffPointer').

inputDataBuffer = int32(zeros(swBufferSize,1));

% Create a pointer to our buffer and the size of the buffer
buffPointer = libpointer('int32Ptr',inputDataBuffer);
buffSizePointer = libpointer('uint32Ptr',swBufferSize);

Defining Device Properties

We need to define the following properties of the device:

  • Sample rate
  • Clock source
  • Mode of operation
  • Input voltage range
  • List of the devices analog input channels we are going to use

 

It is necessary to have the device manual in order to know what valid property values are.

% The Eagle EDRE_DAConfig method requires the device serial
% number to be specified
deviceSerialNumber = 1000000379;

% Specify the frequency at which the data must be
% sampled (Hertz)
samplingFrequency = 100000;

% Specify the clocksource:
% 0: Internal and to External Gate
% 1: Internal
% 2: External Clock
% 3: External Clock and Gate
clockSource = 1;

% Use burst mode?
% 0: Normal Mode
% 1: Burst Mode
burstMode = 0;

% Input range
% 0: -5V to +5V, Single Ended
% 1: 0 to +10V, Single Ended
% 2: -10V to +10V, Single Ended
% 3: -5V to +5V, Differential
% 4: 0 to +10V, Differential
% 5: -10V to +10V, Differential
inputRange = 0;

% Channel list. Must be a pointer to unsigned long.
chanList = 1; % Can be array of channels
chanListPointer = libpointer('uint32Ptr',chanList);

% Gain List. Must be a pointer to unsigned long.
gainList = 1;
gainListPointer = libpointer('uint32Ptr',gainList);

% Channel/gain list size
listSize = length(chanList);

Configuring, Starting and Stopping the Device

After configuring the device with the properties defined above we can start the acquisition. Currently the the device is stopped after the buffer is filled, but there may be a more elegant way of stopping the device after a certain amount of samples have been acquired (for example a timer object could be used to query the device after a certain interval of time).

% Configure the device for analogue input operation using
% the parameters defined above
%
% From the PCI30 manual:
%
% EDRE_ADConfig (ulng Sn, pulng Freq, ulng ClkSrc, ulng
% Burst, ulng Range, pulng ChanList, pulng GainList,
% ulng ListSize)
disp('Configuring for AI...');

calllib('edrapi','EDRE_ADConfig', deviceSerialNumber, ...
samplingFrequency, clockSource, burstMode, inputRange, ...
chanListPointer, gainListPointer, listSize)

% The EDRE_Query method can be used to ask the device about
% itself. Here are some examples of queries (QueryCodes can be
% found in the manual):
%
% Syntax:
% EDRE_Query (ulng Sn, ulng QueryCode, ulng Param)
%
% disp('Query FIFO size:')
% calllib('edrapi','EDRE_Query', deviceSerialNumber, 104, 0)
%
% disp('Query FIFO buffer allocation:')
% calllib('edrapi','EDRE_Query', deviceSerialNumber, 108, 0)
%
% disp('Get ADC range:')
% calllib('edrapi','EDRE_Query', deviceSerialNumber, 113, 0)
%
% disp('Check if ADC system is busy:');
% calllib('edrapi','EDRE_Query', deviceSerialNumber, 103, 0)
%
% disp('Get number of samples available:');
% calllib('edrapi','EDRE_Query', deviceSerialNumber, 109, 0)

% Start the analogue input operation
disp('Starting AI...');
calllib('edrapi','EDRE_ADStart', deviceSerialNumber) % Start
pause(25); % Would be better to query the driver and stop
% after enough samples are acquired

% Stop the analogue input operation
disp('Stopping AI...');
calllib('edrapi','EDRE_ADStop', deviceSerialNumber) % Stop

% EDRE_Query (ulng Sn, ulng QueryCode, ulng Param)
disp('Get number of samples available:');
samplesAvailable = calllib('edrapi','EDRE_Query',...
deviceSerialNumber, 109, 0)

Getting the acquired Data

In this section we retrieve the data stored acquired during the analog input session and unload the .dll.

% Getting data from the driver buffer
% From PCI30 manual:
% Long EDRE_ADGetData (ulng Sn, plong Buf, pulng BufSize)
disp('Getting data from device buffer...');
calllib('edrapi','EDRE_ADGetData', deviceSerialNumber,...
buffPointer, buffSizePointer);

% Unload the driver library. Horrible things can happen
% if you don't unload
% the library in a timely fashion...
disp('Unloading library...');
unloadlibrary('edrapi')

aiData = get(buffPointer,'Value');

plot(double(aiData)/1e6) % Converting to Volts