17-2000 C
2020-09-17
39(50)
ADQ8-8C Manual
17-2000 C 2020-09-17
39(50)
7
ACQUISITION CONTROL
The acquisition control consists of two partly independent parts;
•
Acquisition process: acquisition of data in a record into the DRAM of the digitizer
•
Transfer process: transfer data from the DRAM of the digitizer to host PC.
shows the flow of data through acquisition and data transfer.
7.1 Multi-thread notice
Note that the digitizer does not support multi-threaded applications. In high speed applications, how-
ever, a multi-threading programming style has advantages. In such an application, make sure that only
one thread communicates with the digitizer at a time.
In the example in
, one thread handles the control of the digitizer. The other thread only pro-
cesses data.
Example code available with the digitizer is sometimes written with several threads. Study these exam-
ples carefully to see how multi-threading can be used.
7.2 Acquisition memory
The acquisition memory,
, is of size 1 GBytes.
The memory is shared by all activated channels which means that if only one channel is activated, the
entire memory is available for that channel.
The data memory is also shared between data and headers,
. A header contains information
about the data record, for example, timestamp and channel number. The headers can be setup in two
different modes:
•
In the normal mode, the headers are activated. This mode is recommended for all standard acqui-
sition modes.
•
In the raw mode, there are no headers and all available memory is used for data. The raw mode is
only recommended for custom firmware built in the ADQ Development Kit.
The memory is organized as a FIFO where it is possible to record data and read out data simultane-
ously. This is called readout-while-recording and is available both in multi-record and streaming mode.
#
DESCRIPTION
USER COMMAND
REF
a
The A/D converter digitizes the analog signal and generate a flow of data.
b
The acquisition engine manages the data acquisition and builds records
of the data. The acquisition modes are triggered streaming and Multi-
record recording of data into the DRAM.
The acquisition me
MultiRecordSetup
ArmTrigger
c
The transfer of data to the host PC delivers data in buffers for the user.
User schedules the transfer.
GetDataWHTS
d
User’s application reads data and headers for further processing and/or
storage.
Figure 28: Acquisition control and data transfer.
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