Transmitting Data from 2 Sensors to an Arduino using HC-05 (2 TX, 1 RX)

Hello, everyone! I want to ask something for my college project. I need to transfer data from a load cell. In my project, I am using two load cells, let's call them A and B. For each load cell A and B, I already paired it with Bluetooth Modul HC-05 using Arduino Nano. Now I want to send data from load cell A and B to a single Arduino Uno, which I have a plan to pair it with HC-05 also. So basically, in this project, there are two transmitters (load cell A and B) and one receiver. Is it possible that HC-05 could receive data from two different HC-05? Or I need another HC-05 as a receiver? Please help me, thank you. :smiley:

P.S. : I've already tried using Wireless Modul NRF24L01, but I can not use that because of some reason, so my lecturer suggest me with this HC-05 stuff :slight_smile:

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slithzo:
so my lecturer suggest me with this HC-05 stuff :slight_smile:

Pretty piss-poor advice, I would suggest. Your mother would have told you that this is the sort of job the NRF is made for, and doing it with HC-05 is only for the desperate and incompetent.

As things are, your Uno can handle two Blueteeth, one on Hardware serial and the other on software serial. Just remember to disconnect the one on hardware serial when you upload the programme.

Alternatively, you could have a single master HC-05 on Uno which has its power and EN pins under software control. This enables you to reconfigure it on the fly so that it sequentially auto-connects with the respective slaves on the Nanos.

Nick_Pyner:
Pretty piss-poor advice, I would suggest. Your mother would have told you that this is the sort of job the NRF is made for, and doing it with HC-05 is only for the desperate and incompetent.

My lecturer said that using NRF is bad because of the wifi in the area near the NRF will interfere the connection of NRF itself, so it takes a longer delay for transmitting the data. He said it is correlated with OSI Layer and I actually don't understand with it. Could the wifi in the area near NRF interfere the NRF? Is it because of they have same frequency or what?

Nick_Pyner:
Alternatively, you could have a single master HC-05 on Uno which has its power and EN pins under software control. This enables you to reconfigure it on the fly so that it sequentially auto-connects with the respective slaves on the Nanos.

How to enabling that function so that they could transfer data sequentially? What keyword I should search for this? Thank you.

slithzo:
My lecturer said that using NRF is bad because of the wifi in the area near the NRF will interfere the connection of NRF itself, so it takes a longer delay for transmitting the data.

I submit this is all pretty suss - indeed bluff might be more to the point. WiFi, NRF, and Bluetooth all operate on 2.4GHz so you might wait for a long time to hear a proper explanation as to why WiFi is bad for NRF , but OK for Bluetooth. I'm no expert but I understand that NRF and Bluetooth are much the same but just used in a different way. The actual radio waves transmitted for attack by local WiFi can't be that different.

I actually don't understand with it.

No surprise there, I bet nobody else does either. It really does sound like utter bullshit, and he is just trying to bluff you with technobabble. I guess the real meaning is that you should stop asking awkward questions. One thing is absolutely clear - you do not need to know anything about OSI layers in order to fix a simple Arduino problem.

How to enabling that function so that they could transfer data sequentially?

There is no function per se. I repeat - HC-05 cannot connect with two slaves simultaneously. You must therefore:

  1. configure it to connect with one -get the data
  2. interrupt power, restart in AT mode
  3. reconfigure to connect with other
  4. interrupt power, restart for comms mode
  5. connect with other - get that data
  6. interrupt power, restart in AT mode
    etc., ad nauseam. Easy - what possibly could go wrong?

Frankly, if you have the HC-05s already to hand, and no NRFs, you might as well have two on separate ports as described. Your main objective is get the job done, and they will do it.

If you have no HC-05 yet, nor the NRFs, I believe Bluetooth 4 devices can connect to a few others simultaneously, and you might research that on the Martyn Currey website. A cheap and popular example is the HM-10. The HC-05 is Bluetooth 2.