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Thread: RF peripheral recommendations

  1. #1

    RF peripheral recommendations

    Looking for some project advice if anyone has done much hacking with RF.

    I'm using a Teensy 3.2 to control an LED light system using a custom motherboard that the Teensy plugs into. The Teensy communicates with a peripheral that handles the PWM of the LEDs which speaks UART, but otherwise just stores lighting scripts and plays them.

    My scripts can include strobing modes that operate at 5 to 60Hz. This is simple enough with one light, but I would like to try to create a network of multiple independent lights acting in unison. This is difficult because while the clock drift between lights may no be tolerable for short shows, I do need to be able to tell all of the lights to simultaneously begin a script or else they may be strobing out of phase with their neighbors. Over a few hours of repeating a script over and over they will also drift and need to be resynchronized at regular intervals.

    I am looking for guidance on how I might accomplish this best wirelessly, for a case with perhaps 50 remotes listening for synchronization commands. I have used wifi modules from microchip in the past for this, but due to the large number of devices on one network this results in random fixtures showing latencies of multiple seconds because there's just too much wireless noise in that configuration.

    I have been recommended that I try 802.15.4 without zigbee on top for this to get at least uniform latency reception -- it's okay if all my lights synchronize with 10ms of latency, it just needs to be the same latency for all lights. I was considering an xbee 802.15.4 SMT module for this, which I was thinking to use with their USB dongle so that a computer may act as the master device.

    Does anyone think that this will still have latency issues like with wifi, or have another method that they might recommend? In a pinch I can imagine a simple on-off output that I use as a sync pulse, but true data transmission would be nice so that I can send them new scripts without needing to plug them all in individually to a computer.

    Also considering if the Teensy might not be the best choice here, it would save me a lot of space to not have to use both modules. I think the Photon is probably too much latency, but if there are some microcontrollers with low latency RF transceivers built in for 802.15.4 I'd love to hear about it!

  2. #2
    Senior Member
    Join Date
    Dec 2016
    Posts
    164
    If timing is critical I would use something as simple as possible.

    Either a free usable rf band where you can put out a pulse train or even ir-led's if there's a line of sight.

  3. #3
    Thank you for the advice, I think I may then try the MICRF113 for a super basic transmitter and the MICRF219A or MICRF220 as a basic receiver.

    The transmitter seems simple enough, but the receiver description sounds like something from Star Trek. Love it.

    The MICRF219A has "Auto-Poll" while the MICRF220 has "Integrated Squelch Features". Not sure if either of these are relevant here, but I'll do some more research.

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