ATS9462 User Manual
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A PCI or PCI Express digitizer being used in a PRF or
streaming application is, by definition, doing “burst DMA for
lengthy period”, and is a type of product that can negatively
impact response times of the RTOS.
As such, the claim that an RTOS can remove all timing
uncertainties in PRF application is suspect, to say the least.
Furthermore, you may not be able to get software drivers for
the selected RTOS for all the hardware components you
need for your system.
In summary, moving to a real-time operating system will not
guarantee data throughput, but will surely increase the overall
system cost, increase the cost of software development and
maintenance and limit the number of suppliers for other
hardware components.
Dual Port Memory
The basic throughput problem faced by digitizers is that
almost all of them use single-port memory, i.e. if you are
reading data from the acquisition memory, you cannot
capture into it and vice-versa.
This requires a software handshake which is heavily
dependent on the operating system response time.
ATS9462 solves this problem by providing an on-FPGA dual-
port FIFO and an advanced dual-DMA engine that can
stream data to PC host memory at up to 720 MB/s (exact rate
is motherboard dependent).
Bottom line is that , software does not have to wait until the
end of data capture to read the acquired data.
ACQUIRE
TRANSFER REARM ACQUIRE
This transfer and re-arm time limits the
maximum achievable PRF. Note that the
operating system overheads are part of this
delay
