Hi,
Is there any physical or other type of limitation when putting 300 NRF2401 units to communicate to one NRF2401 unit.
Supose a car parking with 300 places (300 NRF2401 battery powered) and a computer with a NRF2401 to receive signals, to see if there is available places or not to show it on a display at the entrance of the car parking. The system is to work using the push approach (NRF2401’s send periodically info to sink node)
Can this be viable?
Thanks
JohnR
It might be feasible, but not how you describe. You need a
network, with each node communicating with its nearest neighbours.
Leon
But if the transvceivers are installed in an open-space I whink they will communication directly with sink nodes, right?
Remember, the target application is not a car parking. Car parking is just a similar example.
Any problem if they all communicate directly with the sink node?
JohnR
Range?
Leon
25 meters from the sink node with some wood doors in the middle
Maybe those 900 Mhz RF moduls launch the signal more far…
JohnR
Look up a token ring network protocol on the web. Basically the base station sends a ping out to the first unit. The unit then talks to unit two, unit two to three, until all three hundred have been polled. Number 300 sends a message back to home base with the info whether any spaces are open. It’s low tech, but you can build some fail safes into it. Since unit 192 is close to 193, if 193 dies, 192 can jump over it to 194 and send an error number for 193. Conceivably you only need 300 bits of serial data. Each bit equals a full or empty. A few bytes for house keeping, such as a dead unit in the chain, and you are networking baby!
Use the 24L01, as the range is better than the 2401
Ron
Hi Ron,
Look the car parking was a similar example.
In reality, the system will not have all the places with a “sensor”. It will be under subscription. So if the on person subscribes, it will be a sensor on “its place” if not, there will no be a sensor for that person.
At the beginning I cant trust that there will be 300 sensors. At maximum there will be 300 sensors.
On question, why “ping” the first node and then node1 “ping” to node2 and so one and not sink ping node 1 and node 1 answers to sink
sink ping node 2 and node 2 answer and so one.
Ok, in the ring manner there are half of the messages and some batery power is saved.
But is the service is mission critic i think it will be more reliable if sin pings each of the “subscribed” (active) nodes (PULL). Do you agree?
My problem is if I want to put it also to work using push model and pull model.
If some tens on sensor transmite their values at the same time… ok, I have to put ack/nack but is there any other problems if there is a boost of message in the air ate the same time for the same node?
Thanks
JonhR
My problem is also this one
Push is also an important feature because in that way sensors could only communicate when state changes saving power…
JonhR
The reason for a network of sensors, is because 2.4GHz has generally crappy range in the real world. Your trade off is battery power if you increase power. If you do not daisy chain the units, you will more than likely need repeaters to boost the signal to a reliable range that will cover your area in question. 900 MHz will increase range in most circumstances, but I am not as happy with Nordic’s solutions as the Chipcon CC1100 for sub 1GHz transmission.
Ron
Sorry, I did understood very well the last ideas of your last message:
Do you want to say that your choise would be nordic 2.4ghz or Chipcon CC1100 and never 900 mhz, right?
By this order of preference?
I didnt understood also the daisychain. 
So, if were you, do you used ring or pull + push (sink to all nodes one by one) ?
Many thanks
JonhR
If (you need the extra range and you can use 900 MHz){
Choice = CC1100}
Ron
Got it!
Thanks
JonhR
Hello,
You can build this baby: http://www.elektronika.ba/P9020136.JPG
It is CC1101 with 250mW power amplifier. Works great, testing is still in progress. I achieved 1.026 meters of range with no line-of-sight. The signal went from [here to [here. If you are interested, I can give you the schematics.
Regards](Google Maps)](Google Maps)
You’re either going to have to deploy more sinks (on different channels!) or use a multi-hop network. There are various implementations out there - start googling about wireless sensor networks.
Due to conflicts of interest, I won’t go further into this topic 
Dear Muris,
I am interested with your ciruit hence I much appreciate if you can provide me the schematic circuit and source code.
Thanks
Tchau
Hello,
Here you are: http://www.elektronika.ba/629/cc1101-rf … amplifier/
You have a red download button near the end of the page.
Regards
