Is there a DMA mode on USB8451 for data capture?

[Ianopacino]

I want to use the USB8451 for high speed ADC Data capture in a coherent system?. Id like to be able to tell the pod to gather a large number of samples over SPI. Currently the speed is dependant on the speed of the sw loop in Labview. Id like to be able to provide the DATAREADY signal from my ADC to the 8451 and read back from 8451 when the number of samples is ready?.

[muks]

Have you seen this?

[Ianopacino]

My ADC is a 12bit 1 MSPS. I need to gather 2 bytes from the ADC before the next sample is ready. I was hoping I could use my DATAREADY signal as an interrupt to the 8451 and it could send the data fast enough to Labview for post processing.

[memoryleak]

According to the datasheet the maximum SPI rate on the 8451 is 12MHz, or 12MBit/sec assuming the bus is 100% utilized (I don't know if it's possible to get all the way to 100%, in fact it's likely that there's a cycle or two of dead time inserted).   

If you're transferring two bytes (16bits) at 1MSPS, you end up needing to transfer rate of 16MBit/sec, which is significantly over the 8451's abilities.  😞

It may be possible to do this using a beefier HSDIO card to trigger on DATAREADY to begin playing back a waveform (which could be loaded with the SPI signals you desire), but we'd have to wait for an HSDIO expert to confirm this. 

Hugs,

memoryleak