Syncing 2 LED Strobes Via RF
Syncing 2 LED Strobes Via RF
(OP)
I hired an electronics engineer to design a portable LED lighting system that has bluetooth for controlling the LEDs (color change, strobe, brightness, etc.). One of the objectives is to have the ability for each LED lighting system to sync to one another. So for example if one system is strobing at a certain rate then you bring another system near it they would both synchronize and strobe at exactly the same time. My engineer says he thinks the bluetooth protocol would have too much lag to get them in sync. I was thinking about using infrared but these will often be used in direct sunlight so I don't think it would be reliable. I would appreciate any creative ideas in how you think this could be achieved.
Thank you!
Thank you!





RE: Syncing 2 LED Strobes Via RF
I'd probably use a simple wireless scheme that sends out a single sync pulse occasionally. Skip all the protocols.
You can use IR also. It dumps scads of FCC hassles. You would need to modulate the signal and use the correct filters which both raise the signal to noise ratio considerably. It's quite do-able.
Back to the BT. You would find a repeatable time delay that you could just subtract out.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Syncing 2 LED Strobes Via RF
Don
RE: Syncing 2 LED Strobes Via RF
Here's some plain vanilla transmitters and transceivers that would work as radio beacon timebases.
Mouser Sort
Keith Cress
kcress - http://www.flaminsystems.com
RE: Syncing 2 LED Strobes Via RF
Slave Strobes can do this open loop.
RE: Syncing 2 LED Strobes Via RF
Additionally, where the lights are in one's visual field makes a huge difference. Closer to the fovea, your color cones dominate, but are slower, while your peripheral vision is dominated by the monochrome rods, which are more sensitive to flicker. And, while your vision has lag, it is able to detect very short duration pulses, provided they're bright enough.
TTFN

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RE: Syncing 2 LED Strobes Via RF
itsmoked, couldn't I use the bt chip as the radio transmitter and receiver? Since I'm going to have the bt chip there already I'm hoping I don't have to add another rf transceiver to the design.
VE1BLL, I like the idea and I think the strobe would be bright enough for some situations, but I need this to work omnidirectionally in direct sunlight, so I don't think it would be reliable like that.
IRstuff, that's interesting info about the eyes. I didn't know that. I think if I can get them to sync within 30hz of each other it will be good enough, even if some few millisecond delay is noticed that would be okay.
RE: Syncing 2 LED Strobes Via RF
http://en.wikipedia.org/wiki/Persistence_of_vision
RE: Syncing 2 LED Strobes Via RF
Keith Cress
kcress - http://www.flaminsystems.com
RE: Syncing 2 LED Strobes Via RF
RE: Syncing 2 LED Strobes Via RF
RE: Syncing 2 LED Strobes Via RF
As Keith says - just do it.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Syncing 2 LED Strobes Via RF
Gunnar do you recall what current you drove your IR LED at? Did you use more than one?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Syncing 2 LED Strobes Via RF
Thanks,
Don
__________________________________________________________________
Hi Don,
I am writing to update the project progress.
There is a problem with the BLE. The Nordic chip needs a BLE stack (a kind of firmware) to run as a BLE application. My code runs on top of this stack. When two BLE devices talk to each other, one is master and the other one is slave. However, the stack now just allows us to program the chip as a slave when communicating with the smartphone. In order to synchronize the strobe signal among many systems, we cannot uses the BLE protocol. I am searching the solution for this problem and I'm considering some options as mentioned below:
1. The phone is master and every light system is slave. The phone is required.
The synchronization can be done only if there is a phone in the area. This phone can then play the master role.
2. The phone is master and every light system is slave. The phone is not required.
I'm putting forward this method now. Only the transmission from phone to (one) light system is BLE protocol. The communication between two (or more) light systems is our defined protocol. During the synchronization, BLE stack will be disabled and I will use the radio link directly. Thus the phone then cannot detect and connect to the light system. I can add one more button on the light system to enable the BLE stack again when configuring the light system from phone.
ps: actually, now there are 2 BLE stack:
1. Slave (official)
2. Master (beta)
3. Master and Slave (can switch between two mode): This stack is still under developing.
RE: Syncing 2 LED Strobes Via RF
Alternatively, since the master/slave designation only occurs after connection, you could do something a bit tricky like two light systems somehow deciding who should adopt the master role for the present connection. But that's not really how BLE was intended.
RE: Syncing 2 LED Strobes Via RF
http://en.wikipedia.org/wiki/Zigbee
TTFN

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RE: Syncing 2 LED Strobes Via RF
RE: Syncing 2 LED Strobes Via RF
https://www.nordicsemi.com/eng/Products/ANT/nRF514...
Thanks,
Don