Super cool. I'd love to see 2.4GHz LoRA as well.
Benchmarking latency across common wireless links for microcontrollers
11–20 of 36 posts
Re: Benchmarking latency across common wireless links for microcontrollers
#12Something of a tangent but I couldn't find anywhere a way to wirelessly extend usb ports. Allowing you to plug a mouse/keyboard/Yubikey to a computer in another room with minimum latency and without the need of any software or particular drivers. If one wanted to do something like that one would probably start by reading that article I guess. Thanks for this very thorough work.
WiGig docks were promoted for a short while but the problem they ran into was having an e.g. keyboard in another room wasn't very practical unless the display was as well and that bumped the RF requirements. So it ended up in the 60 GHz range which wouldn't make it to the other room and people basically said "eh, what's the point I'll just plug the dock in and it works".
Re: Benchmarking latency across common wireless links for microcontrollers
#13Years ago I was working on a system where an Android device communicated with a web server written in Erlang, and our Android guy was going off about how Erlang was "really slow" and that made no sense to me. So we looked at the interaction times, and it was certainly true that something was slow. Instead of the Erlang server, we swapped out Apache serving a static page. That was slow too. It turned out he'd been benchmarking the crappy wifi connection.
Re: Benchmarking latency across common wireless links for microcontrollers
#14[dead]
Re: Benchmarking latency across common wireless links for microcontrollers
#15Outstanding blog post. NRF24 had been my fav for a long time, I planned switching to LoRa but I didn't know the latency is that high.
You go for LoRa or NBIoT when you need the low power consumption, and especially for deep penetration. Generally, if you have a better option, you use it. LoRa and similar high latency networks can't easily run TCP due to the standard TCP timers (especially Ack timeouts).
What I would like to see is better support from the cloud providers for UDP based protocols such as MQTT-SN.
Re: Benchmarking latency across common wireless links for microcontrollers
#16Great article!
Here's a perspective from a guitarist's viewpoint. Most wireless guitar systems boast latencies below 3ms, with the better ones being closer to 1ms.
Latency is important here because even small delays can be felt by the player. Since sound travels at ~1 ft per 1ms, a delay on the order of BLE is equivalent to playing with the amplifier ~25ft away from you, which is pretty bad.
It is surprising that the best system is actually nrf24, given how old it is (or maybe because of that ?). It also seems to have enough bandwidth to transfer a 24-bit/48kHz signal.
Re: Benchmarking latency across common wireless links for microcontrollers
#17Something of a tangent but I couldn't find anywhere a way to wirelessly extend usb ports. Allowing you to plug a mouse/keyboard/Yubikey to a computer in another room with minimum latency and without the need of any software or particular drivers. If one wanted to do something like that one would probably start by reading that article I guess. Thanks for this very thorough work.
USBAnywhere + any WiFi AP
You would need drivers on the computer and I don't know about latency.
Re: Benchmarking latency across common wireless links for microcontrollers
#18Thanks for sharing your research!
I’ve done some similar, but not as thorough, tests with 2.4ghz WiFi and 915MHz LoRa before. My goal is to sync time across multiple devices that go in and out of range of each other to play 60fps light animations and sound within half a frame of each other (8ms), with spare time for some computation.
I’ve been surprised at how bad some oscillators (or voltage regulators) can be and their effect on consistent latency.
I was having fun experimenting, but this will be really useful to get me back to actually implementing my project.
Re: Benchmarking latency across common wireless links for microcontrollers
#19Super cool. I'd love to see 2.4GHz LoRA as well.
Not a radio guy but, isn't the whole point of LoRa to use lower frequencies for greater range?
Re: Benchmarking latency across common wireless links for microcontrollers
#20This is a great breakdown, although it doesn't go into any detail on the distance trade offs of each transmission type, which is an important part of the comparison. I look forward to when they go into this part of the analysis.