AXIOMTEK DASP-52282, Руководство пользователя

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DASP-52282 Card User’s Manual
Theorem of Operation
32
3.3.2 Circular Buffer for Massive Data Buffering
To achieve the desired double buffering mechanism for
DASP-52282, a 256K word ring 0 software buffer is constructed
by the ring 0 driver of DASP-52282. The ring 0 software buffer
serves as the second data buffer for massive data transfer
between DASP-52282 and host computer. The ring 0 buffer
operates as a circular buffer that will continuously update its
contents and recursively overwrite the contents of the buffer
when buffer is full. Incorporate with a header contains current
status of the circular buffer, user can access the gapless
acquired data through the provided ring 3 API.
3.4 Automatic Scan
To perform high speed multi-channel data acquisition (or
automatic scan), an on board micro controller is used to
manipulate the input multiplexer and the PGA (programmable
gain amplifier) of DASP-52282. Benefited by the capacity of
embedded micro controller, DASP-52282 can perform high
speed channel multiplexing and gain adjustment automatically. A
sequence of instructions to perform automatic scan is stored in
the on chip RAM of the micro controller, and can be software
configured through a complete set of ring 3 API of DASP-52282.
Figure 3-10 describes the principle of operation of auto scan
schematically. The user configured auto scan instructions are
stored into a queue structure, and the on board micro controller
executes these instructions recursively when data acquisition is
triggered.
Ch: 0
Gain: 1
Ch: 1
Gain: 0.5
Ch: 7
Gain: 2
Principle of Auto Scan.