Transmitting Data Wirelessly from my Analog Circuit (short-range)

Discussion in 'Wireless & RF Design' started by roeylazarovits, Apr 17, 2019.

  1. roeylazarovits

    Thread Starter New Member

    Apr 16, 2019
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    Hello!

    I'm working on a project where I want to transmit data from a circuit wirelessly at a short range (< 20 ft) with low latency (< 50 ms). The circuit should be mobile (may move anywhere in the 20 ft range), but I'd like to process the data at my stationary desktop. I am currently using an Arduino to sample data from my circuit and send this data to my desktop for processing. However, I'd like to be able to sample and transmit this data without using an Arduino. I'm not quite sure if this is possible, but I'd love to get some feedback and help in finding potential resources.

    One solution I've considered is using an ADC to sample my analog output, and sending this digitized signal to an RF transmitter. The transmitter would then send the signal to to a receiver connected to my desktop via USB.

    Is this possible (does it even make sense)? Is connecting an ADC to my circuit equivalent to "sampling" the circuit? Does connecting an ADC to my circuit make it compatible with an RF transmitter? Can anybody point me towards specific transmitters and receivers that might handle this? If it's not possible, what other components do I need to include in my design?

    This is my first time posting on this forum, but following others' threads has been a great help in the past. Thank you for any help and advice you can offer!
     
  2. BR-549

    AAC Fanatic!

    Sep 22, 2013
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    Need much more detail. What is the size, weight, and power source and consumption and duration of mobile unit?

    One mobile unit?

    What are you measuring? How often?

    Have you a radio receiver hub for PC. Method of storing and displaying data?
     
  3. NV64

    New Member

    Feb 15, 2019
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    The easiest way is to connect the radio transmitter module to the Arduino. Connect a second Arduino with a radio module to the computer via USB\RS 232\RS 485. The radio transmitter and receiver module can be used for example such: https://www.ebay.com/itm/433Mhz-RF-...282677&hash=item1ed819cf7d:g:ovcAAOSwSGRburpn
     
  4. Yaakov

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    Jan 27, 2019
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    If you replace the Arduino with an ESP8266 and a suitable ADC, you can do this via WiFi.
     
  5. danadak

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  6. roeylazarovits

    Thread Starter New Member

    Apr 16, 2019
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    Thank you all so much for your quick responses! Here are some clarifications:

    My mobile unit is 1 in^2, < 1oz, and uses +9V and -9V. The consumption currently does not exceed 1.5W. These figures do not include the Arduino the circuit is currently connected to, and all dimensions can be changed. Currently, there is only one unit collecting data, but it would be great if I could add additional units to send data to my desktop simultaneously.

    Currently, I am using the Arduino to sample my circuit's output voltage at a 1kHz sampling rate. At the same time that I make my circuit wireless, I'd like to remove the Arduino (so I'd like to avoid solutions involving two Arduinos, like the one proposed here). If I understand correctly, there are receivers that can connect my to my computer via USB, and I can use some Python code to read and process the serial data.

    It seems like transmitting my data using an NRF transmitter without an Arduino will not be possible, as described here. I wouldn't be opposed to indeterminate latency, so long as the latency is consistently below 50ms. Are there any other resources you can recommend to help me learn more about using an ADC and an ESP8266 to transmit data without an Arduino?
     
  7. danadak

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    Mar 10, 2018
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    The ESP8266 has a 10 bit a/d, no specs I can find, and I have read comments
    on web its not so accurate.

    So what accuracy and resolution do you need ?

    These guys make a lot of radio stuff - https://www.nordicsemi.com/Products


    Regards, Dana.
     
  8. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Or if you’re familiar with the Arduino, you can add a WiFi adapter (<$10) and do this. If 10 bit accuracy is sufficient, you won’t need an external need an external ADC.
     
  9. djsfantasi

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    You posted while I was typing my last post. It would help me understand the options available to you, if you could explain why you want to avoid using an Arduino?
     
  10. roeylazarovits

    Thread Starter New Member

    Apr 16, 2019
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    10 bit resolution should work for now, but I'd likely need to upgrade the resolution in the future (16 bit is ideal). Are there similar components to the ESP8266 that could achieve higher resolution?

    My main concern with the Arduino is it's too large for my mobile device. I'd like to keep the size at 1 in^2, and I don't think there are Arduinos that would meet this spec.

    In case the WiFi approach does end up being too inaccurate, does anybody know of an RF transmitter/receiver that can be used without a microcontroller?

    Again, thank you all for your help!
     
  11. djsfantasi

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    There may be an Arduino that meets or is close to that spec. An Arduino Nano is 0.7”x1.73”. That’s 1.2 square inches.

    Take a look here!

    I just used one in a project. Here’s a pic. The circle is 8” in diameter.
    07770EA4-FE92-4DE3-A309-10D3C3032D79.jpeg
     
  12. NV64

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    Feb 15, 2019
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    For example, the STM32F373 microcontroller has a 16-bit ADC. For wireless connection to the computer, you can also use RF\Bluetooth\wi-fi module or ESP8266.
    To reduce the size, you can make your PCB.
     
  13. BR-549

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    One might consider an induction loop, instead of a RF link.
     
  14. Yaakov

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    Jan 27, 2019
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    By the way, the ESP8266 is compatible with the Arduino IDE.
     
    djsfantasi likes this.
  15. danadak

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    Last edited: Apr 19, 2019
  16. roeylazarovits

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    Apr 16, 2019
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    I should have mentioned another reason for not wanting to use an Arduino is because I feel there exists a more elegant solution. Since I am not doing any signal processing on the mobile device, a microcontroller would be overkill, and I should be able to build a sufficient device to simply acquire and transmit data.

    In any case, you've all been a great help showing me where to start with this task, and I appreciate your help immensely! I will post back here if I find that one of these suggestions works best, or if there are any other interesting resources on the topic.
     
  17. BR-549

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    One elegant solution is to FSK an induction loop, inside another induction loop.
     
  18. djsfantasi

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    Ok. I can’t argue with what you think. I’m outta here.

    IMHO, you’re never going a solution.
     
  19. Yaakov

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    Jan 27, 2019
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    For the record, I think that doing electronic contortions to avoid the lowest cost and most flexible solution to the problem for the sake of, what I can only think of as appearance, is not more “elegant”, it’s the opposite.

    MCUs are cheap, very functional, and readily available. I can perceive no benefit of a less functional analog route that somehow avoids them. Including an MCU in such a device is simply sensible, working to leave it out is... something else.

    I do hope you are successful, but I don’t understand why you’d want to spend more time and money to do something that provides no functional benefit.
     
  20. bug13

    Senior Member

    Feb 13, 2012
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    Here is a tiny Arduino (since your code is already working):
    https://www.dfrobot.com/product-1075.html

    Also you mention you want to use an 16-bit ADC, you may need to integrate some low noise design, and/or pay special attention in the firmware. Or you may end up with only 10 useful bit in a 16-bit ADC. Especially you have a wireless transmitter in your design.
     
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