Direct Digital IO-Wireless Transmission

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
I am looking for some advise on how to transmit status of a digital pin over wireless. I will have a transmitter module whose digital pin will be toggled. It can toggle at a rate of 1Hz up to 1kHz. I want to reflect same toggle on the receiver side. Receiver should also have digital pin that gives the current state of Tx module digital pin.

Now I have already tried with XBee Series 2 IO line passing but it works near the lower toggle rate (1 Hz) but does not seem to work on higher toggle rate. Any advise or help would be beneficial.
 

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dendad

Joined Feb 20, 2016
3,611
What distance are you wanting to run the link over?
And the power supplies available?
What latency is tollerable?
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
What distance are you wanting to run the link over?
And the power supplies available?
What latency is tollerable?
Link distance 100m+ the longer the better
Power supply will be available
There can be delay in transmission but over all delay should remain the same. This toggle will be happening continuously at specific frequency so if there is delay then that delay should be constant

I hope i answer what you wanted to ask
 

dendad

Joined Feb 20, 2016
3,611
You will run into interferance from mobile phones in the close proximity with a lot of radio links. Is there any reason you cannot run wires?
Or an infa red light beam?
And mentioning the mobile phone interferance and the modules you have tried up front would be a help. Any info you can think of can make a difference to the responses to your question. It is likely more answers will come if people can see you have already tried things.
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
You will run into interferance from mobile phones in the close proximity with a lot of radio links. Is there any reason you cannot run wires?
Or an infa red light beam?
And mentioning the mobile phone interferance and the modules you have tried up front would be a help. Any info you can think of can make a difference to the responses to your question. It is likely more answers will come if people can see you have already tried things.
So far I i have tried 433MHz transceivers and Xbee. I love both but both have their own issue. XBee IO line passing is slow and 433MHz has interference issue.

I cannot run wires, in fact i run wires until now and keep wire length up to 10m. But from practicality point of view i want to make myself independent of lenght and wiring mess.

About infrared, what distance we can achieve and is it going to be line of sight or obstacles can come in the way. This would sound interesting. I did not try this so far.

Last, right now I am talking about one transmitter and one receiver. Final goal would be one transmitter and multiple receiver.
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
It would be only one signal in broadcast mode. So any of the receiver can get that timing signal.
Do you merely want to send a timing signal? Can it be the same signal or one of two or three signals?
It would be only one broadcast signal. Any receiver tuned to that channel should be able to get that
 
I am looking for some advise on how to transmit status of a digital pin over wireless. I will have a transmitter module whose digital pin will be toggled. It can toggle at a rate of 1Hz up to 1kHz. I want to reflect same toggle on the receiver side. Receiver should also have digital pin that gives the current state of Tx module digital pin.

Now I have already tried with XBee Series 2 IO line passing but it works near the lower toggle rate (1 Hz) but does not seem to work on higher toggle rate. Any advise or help would be beneficial.

Not sure that this will help and I have not thought it through at length, but:

Given that two approaches, that seemed sound to me, have failed, what about going digital using the venerable Nrf24L01?

https://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo

Given round trip packet transfer times of 1828 microseconds (from the above page), you could probably support one way "toggle" transfer rate of 1 kHz.
Your packet would be minimal, sending as little as one byte to indicate 'on' or 'off'. Receiver side digital pin reflecting transmitter toggle pin is easily accomplished with the connected controller. You could even have some error correcting if you sent a larger packet, I would think.

Maybe worth a try or at least some consideration.
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
Not sure that this will help and I have not thought it through at length, but:

Given that two approaches, that seemed sound to me, have failed, what about going digital using the venerable Nrf24L01?

https://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo

Given round trip packet transfer times of 1828 microseconds (from the above page), you could probably support one way "toggle" transfer rate of 1 kHz.
Your packet would be minimal, sending as little as one byte to indicate 'on' or 'off'. Receiver side digital pin reflecting transmitter toggle pin is easily accomplished with the connected controller. You could even have some error correcting if you sent a larger packet, I would think.

Maybe worth a try or at least some consideration.
Thanks. I would have a look over this. I wanted to avoid micro controller but I will give it a try
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
You would probably get less interference from other signals if you used a superhetrodyne receiver such as this one. Your existing transmiter should work with this.

Les.
Yeah I have seen this. By the way, I did test just now. If I place my mobile phone very close then only I have interference otherwise it is okay. But since I was reading too many things on this I got confused on this point. We cannot use 433MHz band for our customised projects? Will this require us to buy a license? I mean is this frequency band not available for worldwide? 2.4GHz transceivers seem to be worldwide allowable. May be I am confusing this point. My main question if, can I use 433MHz transceiver for short term use worldwide or this is only allowed in certain regions?
 

DickCappels

Joined Aug 21, 2008
6,640
Generally there is wide acceptance of the ISM bands, of which 433.92 MHz is the center of one. I am pretty sure from a project about 10 years ago that there was not much choice in China and 433.92 MHz was not permitted. You really need to check on a country-by-country basis, especially if you are developing a commercial product. Certification or verification may be required for many countries.

https://en.wikipedia.org/wiki/ISM_band
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
Generally there is wide acceptance of the ISM bands, of which 433.92 MHz is the center of one. I am pretty sure from a project about 10 years ago that there was not much choice in China and 433.92 MHz was not permitted. You really need to check on a country-by-country basis, especially if you are developing a commercial product. Certification or verification may be required for many countries.

https://en.wikipedia.org/wiki/ISM_band
Thanks. I am going to give NRF24 a try and see how it works. 2.4GHz is accepted worldwide but not sure whether it will work in my case or not.
 

DickCappels

Joined Aug 21, 2008
6,640
I was advised that Bluetooth was acceptable to China, and I think most of the rest of the world. If you are planning so sell anything you still need to check the rules and regulations for each market. The bands may be the same but the requirements are often different.
 

ericgibbs

Joined Jan 29, 2010
11,095
Thanks. I am going to give NRF24 a try and see how it works. 2.4GHz is accepted worldwide but not sure whether it will work in my case or not.
Hi,
I developed a multi-pipe system using the NRF24, it had a very limited range, around 10 to 15mtrs, I would say for 100+mtrs you will need a dipole antenna and line of sight transmission path.
Look at the PDF section for just detecting the carrier, may suit your App.
E
 

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Last edited:

DickCappels

Joined Aug 21, 2008
6,640
There are things like this out there. <= this particular one has a range of about two miles, but because of its transmitting frequency it can only be used in the Americas.

You can check out the band availability in various ITU regions by consulting this table.
 

LesJones

Joined Jan 8, 2017
2,726
If you use a frequency that does not require a licence in your country then there in nothing to stop someone else near by also transmitting on that frequency which would cause data loss on your system. The very limited way you have described your system I can't see how you can make it fault tolerant. If you give more details about EXACTLY what you are trying to achieve then there is more chance of getting a solution.

Les.
 

Thread Starter

ammaranwar

Joined Mar 23, 2010
9
If you use a frequency that does not require a licence in your country then there in nothing to stop someone else near by also transmitting on that frequency which would cause data loss on your system. The very limited way you have described your system I can't see how you can make it fault tolerant. If you give more details about EXACTLY what you are trying to achieve then there is more chance of getting a solution.

Les.
1. Free to use that frequency worldwide. It will be integrated into commercial product
2. Intermittent data loss/error is not a big issue. I know it sounds strange. System (connect to receiver) will keep on monitoring the On/Off frequency for some time. Even if some interference is giving erroneous results it is okay. BUT if interference is present all the time, then obviously we will not use this mechanism. As mentioned earlier, we are using wired connection of 10m where 5V pulse is switched On/Off. If we cannot use wireless due to interference then wired connection will be used. But ideally we want to use wireless to extend the range and avoid wires. This transmission needs to be done for both indoor and outdoor.
3. The frequency at which Digital pin can toggle is up to 1kHz or as slow as 1Hz.
4. I have used XBee and it works fine up to 10 Hz.
5. I have used 433MHz transceivers, and their response is acceptable. Only issue is that we cannot use it Worldwide. In fact I used this transceiver yesterday and found out exactly what i wanted. But after a little bit of research I found out it is only allowed in Region 2 countries.
6. Going to try IRF24 next week.
7. Rx-Tx distance of 10-20m would be most of the cases but if we can extend that, it would be great.

If you need any specific information, please let me know.
 
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