ADC 400F Manuál stáhnout pdf (Strana 28)

Chapter 2. Setting up the software

Ì The CAnalyzer reference that will be passed in to the operator() member function is really a

reference to a CTclAnalyzer. Since we will be calling member functions of CTclAnalyzer

directly, we must include the header of that class as well

Í This section of code deﬁnes sevaral constants that help us unpack data longwords from the CAEN

V785 ADC. See the hardware manual for that module for a detailed description of the format of the

buffer produced by this module. Whenever possible avoid magic numbers in code in favor of

symbolic constants as shown in the listing. Symbolic constants make the code easier to understand

for the next person and for you if you have to look at it a long time later. The constants are:

CAEN_DATUM_TYPE

This is a mask of of the bits that make up the ﬁeld in the V785 data that describes what each

longword is.

CAEN_HEADER

If the bits selected by the CAEN_DATUM_TYPE are equal to CAEN_HEADER the longword is an

ADC header word. Thus you can check for header-ness with code like:

if ((data & CAEN_DATUM_TYPE) == CAEN_HEADER) { ...

CAEN_DATA

CAEN_DATA selects ADC data longwords in a mannger analagous to the way that

CAEN_HEADER selects header words. If the bits of a longwords of V785 data are anded with

CAEN_DATUM_TYPE, and the result is CAEN_DATA the longword contains conversion data.

CAEN_TRAILER

If a longword of CAEN V785 data, anded with the CAEN_DATUM_TYPE mask is

CAEN_TRAILER, the longword is an ADC trailer and indicates the end of an event from the

module.

CAEN_GEOMASK and CAEN_GEOSHIFT

These two values can be used to extract the Geographical Address ﬁeld from data returned by

the CAEN V785 ADC. The Geographical Address is what we have been loosely calling the slot

of the ADC. The following code snippet is a recipe for getting the geographical address from

any of the longwords that the module returns:

unsigned long slotNumber = (data & CAEN_GEOMASK) >> CAEN_GEOSHIFT;

CAEN_COUNTMASK and CAEN_COUNTSHIFT

These two values can be used to return the number of channels present in an event from the

CAEN V785 adc. The number of channels present in the event is available in the header word

for the ADC data. Given a header word, this information can be extracted as follows:

unsigned long channelCount = (header & CAEN_COUNTMASK) >> CAEN_COUNTSHIFT;

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ADC 400F Manuál Strana 28