Thread: How to convert this into a meaningful timestamp

the documentation for this particular piece of equipment gives the following:

Code:

struct 
{ 
  UINT32  CycleOffset : 12; 
  UINT32  CycleCount  : 13; 
  UINT32  Second      : 7; 
}BUSTIME; 
 
 
which is:  
 
Bit[11..0]  = Cycle Offset in parts of 1/3072 (=24.576 MHz) 
Bit[24..12] = Cycle Count 
Bit[31..25] = Second Count

the author of this documentation is...terse, to say the least.

my problem is that i need to ensure that the data i am retrieving from it is obtained after the function call is made. typically not a problem, but this has a buffer ring, and even if i drain it completely on each acquisition cycle, sometimes the data is still from the past :\


the only timestamping information is as follows:

UINT32[2] RxTime Out Receive time as 100ns ticks since 1.1.1601.
UINT32 BeginCycleTime Out When frame start events are active this is the bus time when
the frame start was detected (for bus time see remarks).
UINT32 EndCycleTime Out This is the bus time when the frame end was detected (for
bus time see remarks).

does anyone see a way to obtain the time that the data was actually acquired by the hardware? RxTime connotes to me the time when the data was transferred to me (which is not helpful), as opposed to when it was copied into the equipment's local buffer.

So it's in "DMA - Replace Mode" then?

yes.

Is this really what you need to do? That would be FGFRAME.Id if so.

no. i don't care about grabbing every frame. there will be many stolen frames.

Also, I would guess that RxTime does not refer to when the function returned. When the frame was placed in the "Ready-Queue" would make more sense.

any guess as to which windows function converts RxTime? the doc says it can be done but doesn't clue you in as to which one is appropriate.

thank you!