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Comment by ellisd | Hacker News Reader

On this topic: I'm very interested in streaming accelerometer data in real time from a wrist worn device to a body mounted LED controller. My goal is to modify the LEDs animations based on the hand position. Given the sensor bitrate and low latency required for this data, it would appears that BT Classic may be better solution than BLE. Beyond the power consumption needs, BLE connectionless broadcasting of the data seems easier to handle with than having to manage pairing two device. You could simply pick the strongest signal and be reasonable assured that it's your personally worn wrist device.

Am I missing something?

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Where are you planning to use this, is it for a stage or concert? A lot of folks have found in those environments 2.4 ghz wireless (like bluetooth) is flakey and unreliable from all the interference of the audience's devices. I've read folks prefer stuff like 900mhz where almost no one has stuff using it in the area. Akiba and Freaklabs has done some great write-ups about his stage show work that are worth exploring: https://hackaday.com/2013/12/10/get-tangled-up-in-el-wire-wi...

Off stage, within the 2.4 ghz ocean: the audience. Your point is well taken that spectrum saturation will be an issue. Low range/power consumption, not centralization are the driving factors in the design. Thanks for the share!

Why use Bluetooth at all? Depending on the details, hiding a wire inside a sleeve should be doable. If you really want wireless, I’d suggest considering something like RFM69 / RFM95 type radios. You can easily find a wide variety of form factors, optionally with integrated Arduino compatible MCU, from Adafruit.

It's a really good point, a wire based sensor eliminates a dead battery and interference as failure points. The Wireless accelerometer feature should come after the basic animation concepts have been ironed out and tested. I really appreciate the reference to RMF* type radios - I had not come across them in my reading.

> I really appreciate the reference to RFM* type radios

My pleasure. It’s surprising to me how many makers / hobbyists who need wireless don’t know about them so I make it a point to bring it up any time I can. I’ve built dozens of fun projects using them and find them to work really well for my needs. There’s trade offs between the 69s and 95s, so be sure to read up on adafruit’s site to decide which works better for your needs.

> You could simply pick the strongest signal and be reasonable assured that it's your personally worn wrist device.

> Am I missing something?

Phone is in your pocket, wrist worn device is on other side of your body. Another device with unobstructed line of sight across the room may have a stronger signal strength.

I'm actively trying to avoid a phone, rather a dedicated LED controller likely containing an AVR or ESP32. A simple button based paring process to associate the wrist band with its personal controller is likely necessary to solve the RSSI issue you point out.

Just use a wire?

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