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I would like to place analog sensor in a place, that is impractical to reach with a wire. But it looks like an overkill to use a separate small Arduino board to read and transmit sensor signal to main Arduino board at a close range (~1 m).

Is there a cheap practical way to setup such sensor signal broadcast over RF without using Arduino board? Something that could work for considerable duration with a small tablet like battery?

  • Thank you both for very helpful solutions. I've chosen first one, because in Aliexpress at a lot of 10 I can get all needed components for ~1 EUR and second solution at a lot of 10 costs ~1,8 EUR. Will consider all pros and cons and maybe even stick to pricier solution due its ready-made nature. – wilkas Sep 24 '15 at 11:49
  • What kind of sensor? E.g. there are wireless temperature sensors that you can buy in the store, and the signal those send out can be pretty easily read by and arduino. – Gerben Sep 24 '15 at 14:39
  • I've meant solution available for different sensors not only temperature. I did find wireless sensors to purchase, but these were kind of expensive. – wilkas Sep 24 '15 at 15:37
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You don't have to use a $30 Arduino. You can make a "breadboard" one for a few dollars, like this:

Breadboard Arduino

$5 for the chip and a couple of dollars for a couple of capacitors and resistors.


Add to that a NRF24L01 transceiver like this:

NRF24L01

Available from eBay for around $1 each. You need two, as you need to transmit from one and receive from another.

So the whole thing could be done for under $10.


Something that could work for considerable duration with a small tablet like battery?

See Power saving techniques for microprocessors

  • So the only solution is to use NRF24L01 transceiver and barebone Arduino or ATtiny chip. There is no cheap ready-made transceiver that I could connect to sensor and a battery? If no other solutions will be given by other members, I'll select your explanation as an answer. Thanks! – wilkas Sep 24 '15 at 8:24
  • I don't know of any ready-made transceivers that will happen to work with your Arduino base-station. – Nick Gammon Sep 24 '15 at 21:05
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I would recommend investigating the ESP8266 modules. Many people use them as a WiFi interface to an Arduino, but they are also capable of being used completely standalone.

You can pick up a cheap module and program it using a readily available USB to TTL UART adapter using the ESP8266 plugin to the Aduino IDE.

https://github.com/esp8266/Arduino

It's like having an Arduino and a WiFi interface all embedded in one chip, and the modules are tiny too - perfect for embedding in a project.

There are many different modules available, some with more pins than others for IO. The best one is the NodeMCU since it has the programming interface built in (go for version 1.0 not version 0.9 since it has better IO options), but the higher end ESP8266 modules on carrier boards (ESP-12, etc) are as good, if a little harder to work with.

  • Is it possible to have the ESP8266 run for a reasonable amount of time (>few months) on batteries? I haven't seen any projects that use batteries on the ESP8266. – Gerben Sep 24 '15 at 14:37
  • There is a sleep mode available on it. I don't know how effective it is, or how you use it, but it does exist. – Majenko Sep 24 '15 at 14:39
  • You can probably get it to work if you only send an update every hour or so. More frequent updates will probably drain the battery too soon. Setting up a wifi connection take quite a bit of time. Optionally you could batch upload the data. – Gerben Sep 24 '15 at 14:45

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