I am working on a wireless telemetry project with a bit of a twist.
I have a CC3220 inside of a rotating shaft connected to an AMS board collecting pitch readings from a magnet mounted inside.
The data is being sampled at 20 MHz and stored locally on the MCU. After 5 seconds of collection, the data is wirelessly transmitted (over Wi-Fi) to my computer where some software crunches the results to display graphically.
Along with the pitch measurements being collected inside the shaft, I am also gathering other metrics with sensors connected directly to my computer. I would like to see how the pitch affects these other readings, so I need to stitch the data together after I send it over Wi-Fi.
The problem is with lining up the data. Because the MCU is separate from the rest of the sensors, it doesn’t start at the same time that I start the others because of the delay induced by using Wi-Fi, so I don’t know the initial time of the first pitch reading to line up with the rest of the data I collect.
I started looking into other RF solutions, including Bluetooth and Zigbee but had to rule those out because of the latency (3 seconds and 15 milliseconds respectively.) This got me wondering if there was ANY wireless protocol that has a latency of less than half a millisecond. The transmission would only have to be one-way. A simple pulse meaning “GO!” to start sampling; then using Wi-Fi to send the data back. If there is no RF solution then I will have to re-engineer the housing to allow a laser diode to have line of sight, but this will cause the cost of this project to skyrocket… which I would like to avoid!
Do you guys have any suggested reading on RF latency? Have any of you had to overcome a similar problem? If you need any more info let me know, I’m not very experienced yet, but that’s why I’m here trying to learn!