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ATS9360 User Manual
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 and the entire on-board memory acts like a very
deep FIFO.
Note that a DMA is not started until RecordsPerBuffer
number of records (triggers) have been acquired.
NPT AutoDMA buffers do not include headers, so it is not
possible to get trigger time-stamps.
More importantly, a BUFFER_OVERFLOW flag is asserted
only if the entire on-board memory is used up. This provides
a very substantial improvement over Traditional AutoDMA.
NPT AutoDMA can easily acquire data to PC host memory at
the maximum sustained transfer rate of the motherboard
without causing an overflow.
This is the recommended mode of operation for most
ultrasonic scanning, OCT and medical imaging applications.