Nrf24L01+ to gpu lowest latency

[Joe Wright]

Hi, I have the opportunity to bid for some research funding for my project, and I'm thinking of speccing a workstation for processing video in realtime, and sensor data in real time.

For both situations, I'm interested in the lowest latency possible. For the sensor data, one or more nrf24l01+'s will be used to collect the data. What is the best way to transfer this to the gpu? I'm thinking of some sort of PCIe interface then gpudirect rdma or directgma.

I'm completely new to this kind of thing, and researching online appears confusing. I see there's quite a few gpudirect compatible products like high speed NICs or fpdp ports but I'm talking about stuff I don't know enough about.

At the moment, I'm going nrf24l01+ to stm32 to usb to pc. Wanting to know how to minimise the hops for a gpu workstation (Tesla, Firepro, etc...).

Thanks, Joe

[Joe Wright]

Thanks. I think the latency will probably be ok but I'm interested in what's the best possible. I think ultimately, to get to the GPU in the shortest amount of time, I would have to make my own PCIe card and use the DMA access (gpudirect RDMA or directgma). Not a simple thing and I haven't found any off the shelf options including an MCU that I can programme to take data in via SPI. So I would have to do a lot myself (PCIe interface, etc) and I don't fancy that.

For video there's quite a few PCIe options that are compatible with the gpu DMA schemes, designed for broadcast video applications I think.

Anyway, thanks for your thoughts. Joe

[ovrebekk]

I am sorry I couldn't be of more help...
If you end up going down the USB route you might want to consider the recently released nRF52840 device. It contains a built in USB device interface, and the radio uses DMA rather than SPI internally, so it should be a bit quicker than an nRF24L01+ connected to a separate MCU.
The drawback of this solution is that you have to write some dedicated software for the nRF52840, and you will still be limited by the latency of the USB.