AlazarTech ATS9462, Руководство пользователя

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ATS9462 User Manual 47
No Pre-Trigger (NPT) AsyncDMA
Many ultrasonic scanning and medical imaging applications
do not need any pre-trigger data: only post-trigger data is
sufficient.
NPT AutoDMA is designed specifically for these applications.
By only storing post-trigger data, the memory bandwidth is
optimized.
NPT AutoDMA buffers do not include headers, so it is not
possible to get trigger time-stamps.
A BUFFER_OVERFLOW flag is asserted if the Data FIFO
overflows.
Continuous AsyncDMA
Continuous AutoDMA is also known as the data streaming
mode.
In this mode, data starts streaming across the PCI bus as
soon as the ATS9462 is armed for acquisition. It is important
to note that triggering is disabled in this mode.
Continuous AutoDMA buffers do not include headers, so it is
not possible to get trigger time-stamps.
A BUFFER_OVERFLOW flag is asserted if the Data FIFO
overflows.
The amount of data to be captured is controlled by counting
the number of buffers acquired. Acquisition is stopped by an
AbortCapture command.
Continuous AutoDMA can easily acquire data to PC host
memory at sustained rates up to 720 MB/s without causing
an overflow. This is the recommended mode for very long
signal recording.
Triggered Streaming AsyncDMA
Triggered Streaming AutoDMA is virtually the same as
Continuous mode, except the data transfer across the bus is
held off until a trigger event has been detected.