I'm looking to control LED's mounted to wristbands. I'd like them to be lightweight and low power (to keep size down).
I'm looking at the nRF24L01 or maybe even the Particle Photon (adafruit product), but I'm not sure if this is what I need.
I guess I could pick up a nRF24L01 and then build my own board for it. That's not to bad to do. If I did that, what would I need to make it happen? A micro-controller, voltage regulator, battery supply, etc.
Even if I could make 2 wrist bands and then control them via my laptop and my home wifi that would be a huge success for me.
Could I send the wireless signals using artnet? Control the LED's that way?
I'm at the point here it seems like a good idea, I'm just not sure which direction to head in.
A wireless transceiver, as is the NRF24L01, is not the same as an internet-capable device. What you are proposing, in such a small size, probably would require purpose built circuitry.
PaulS:
Would that do any good? Are the watches also going to be using artnet (whatever that is)?
From what I understand artnet is a protocol to send data via wifi.
jrdoner:
A wireless transceiver, as is the NRF24L01, is not the same as an internet-capable device. What you are proposing, in such a small size, probably would require purpose built circuitry.
Could I pair the transceiver with the proper circuitry to do such a task? Or am I starting this in the wrong place?
This sounds interesting, but as i look at it more and more, it looks like a major power suck. If that is the case, I don't know if that is the road I can go down.
If you use WiFi, you need to be able to transmit, and to transmit you need power. But only while you transmit. It makes no difference what hardware you are using; it will require power to transmit.
As far as wristbands go, you should consider the power consumption, firstly for what LED you want to power, and then the receiving device for the wireless data. You could do this with a NRF24L01, but the reverse-F antenna-on-PCB arent that great at receiving unless you have a powerful NRF24L01 transmitter (PA+LNA)
I am assuming you want to receive over distance ?
I did quite a nice project transmitting and receiving DMX, not quite ArtNet, but it all depends on how many channels you are after doing
I think the ESP8266 devices are a bit more power hungry than the NRF24L01
Plus, you can set the NRF24L01 receivers to receive ONLY, so they dont have to transmit an ACK, saving power
If you are thinking you could do this from a 3V button battery, forget it, I tried, they just dont have the ooomph ! Although there are a few decent (but expensive) mini 3.7V lithiums out there which might do it
I would suggest you need at least 150mA to run an Atmel, a NRF, and an LED, so budget around that
As a complete change in direction you could always go for a much lower frequency band and go with serial RF modules that you can buy for a couple of quid a pair
mcnobby:
As far as wristbands go, you should consider the power consumption, firstly for what LED you want to power, and then the receiving device for the wireless data. You could do this with a NRF24L01, but the reverse-F antenna-on-PCB arent that great at receiving unless you have a powerful NRF24L01 transmitter (PA+LNA)
I am assuming you want to receive over distance ?
I did quite a nice project transmitting and receiving DMX, not quite ArtNet, but it all depends on how many channels you are after doing
I think the ESP8266 devices are a bit more power hungry than the NRF24L01
Plus, you can set the NRF24L01 receivers to receive ONLY, so they dont have to transmit an ACK, saving power
If you are thinking you could do this from a 3V button battery, forget it, I tried, they just dont have the ooomph ! Although there are a few decent (but expensive) mini 3.7V lithiums out there which might do it
I would suggest you need at least 150mA to run an Atmel, a NRF, and an LED, so budget around that
As a complete change in direction you could always go for a much lower frequency band and go with serial RF modules that you can buy for a couple of quid a pair
Thank you for the info! I really appreciate it. Power is definitely a big worry for me as well. I'll check out your other post on what you did via DMX. I guess, it's what protocol will be best for this system. I'm not hung on Artnet, but open to any other forms as well. I believe osc is another form as well.
Distance up to 100m max I'd think.
I was thinking of using one of those small 12v batteries potentially. Thank you for the power budget tip!
mcnobby:
Also, on the NRF24L01 side, I did a quick round up of all the different types of NRF modules there are out there, appx costs and pictures
The antenna improves the distance, but my test have shown that the improvement is on the receive rather than the transmit, so I used the NRF+Whip on the receivers too
I originally wanted a TX board with a whip antenna, and all the receivers to just use the NRFs with the PCB antenna, but I couldnt get a good signal throughput, or reliability
In the end my set up can happily transmit and receive up to about 20-25ft, which is fine for my application
What I should do is upgrade the transmitter to the LNA+PA version (which takes a bit more power) and use this with the PCB antenna receivers, but you have to take care on power levels when transmitting on the same frequency (FCC rules) and these things could get you into trouble on hi power setting, so I plan to only use a power setting that is appropriate to the job. I also think the LNA (low noise amplifier) improves sensitivity so that will help with range/power too
These days I am more focussed on other things but I have a plan to move to these boards for both TX/RX
They dont need any external antenna, and some say they can TX for 1km, although this has to be proven to me. I bought about a dozen of them, and the price seems to be very competitive with the bulkier whip antenna version. These are really tiny at 27mm x 12mm with a 1.27mm connector pitch !!
mcnobby:
The antenna improves the distance, but my test have shown that the improvement is on the receive rather than the transmit, so I used the NRF+Whip on the receivers too
That goes back to the reciprocity argument we were having a while back.
Matching of the receive antenna is exactly as important as on the transmitter.
Matching of the receive antenna is exactly as important as on the transmitter.
Agreed, I also found direction of antenna makes a difference too, but to get a real handle on all the 'variables' you need some good kit and an open test site