Simple way of wirelessly sending analog reading?

Thread Starter

summersab

Joined Apr 8, 2010
146
So, I've certainly done my share of Googling on this one, but having never done anything wirelessly, I'm either not understanding what I've found or searching the wrong terms. To ask in the simplest terms, what is the easiest way to send an analog reading wirelessly? For example, say I have a circuit where I want to measure a voltage output ranging from 0-5VDC. Normally, I'd grab a multimeter and test it locally. Is there a way to transmit that output wirelessly to a second circuit where I can then read the same output with my multimeter? That's . . . basically it. Beyond that, low-power and cheap are ideal, but I'm just tinkering. :)

Thanks!
 

joeyd999

Joined Jun 6, 2011
4,291
So, I've certainly done my share of Googling on this one, but having never done anything wirelessly, I'm either not understanding what I've found or searching the wrong terms. To ask in the simplest terms, what is the easiest way to send an analog reading wirelessly? For example, say I have a circuit where I want to measure a voltage output ranging from 0-5VDC. Normally, I'd grab a multimeter and test it locally. Is there a way to transmit that output wirelessly to a second circuit where I can then read the same output with my multimeter? That's . . . basically it. Beyond that, low-power and cheap are ideal, but I'm just tinkering. :)

Thanks!
The way I would do it today is with something like a Microchip RN4020. The module is self-contained, runs stand-alone or in conjunction with a MCU, and includes an A/D and I/O. You can write a script for it where it will collect and send data automatically to a mobile device via bluetooth LE.

Ok, so it's not simple simple, but, damn if its not far simpler than things like this have been in the past.
 

crutschow

Joined Mar 14, 2008
24,062
In general it's not easy to wirelessly send a DC analog signal as an analog value with any degree of accuracy. That's why it's typically converted to a digital word and then that word is sent wirelessly. That way the signal can be sent with the accuracy of the original analog to digital conversion as long as the word value is sent without error (which is comparatively easy to do).
That's what joey's solution does.
 

Thread Starter

summersab

Joined Apr 8, 2010
146
I imagined it would have to be converted to some sort of analog signal (which I'm totally fine with). I suppose I just have no idea how to get there. I'm poking around for an example circuit that shows how the RN4020 could be used for this purpose, but I'm not seeing much at first glance. I see it has a built-in ADC (so that's nice). Is there any simple example you could point me to?
 

joeyd999

Joined Jun 6, 2011
4,291
I imagined it would have to be converted to some sort of analog signal (which I'm totally fine with). I suppose I just have no idea how to get there. I'm poking around for an example circuit that shows how the RN4020 could be used for this purpose, but I'm not seeing much at first glance. I see it has a built-in ADC (so that's nice). Is there any simple example you could point me to?
Start with this and pay special attention to section 2.3.8 (scripting).

It will be most easy if you purchase one of these (about $49).
 

djsfantasi

Joined Apr 11, 2010
5,913
I don't know if there is s "simple" way.

First, you need a method of capturing the analog data. As several have mentioned, to transmit this data, converting this to digital form is best.

Hence the second requirement - an analog to digital converter or ADC

Third, you need to select and become familiar with a wireless technology. WiFi, Bluetooth or RF come to mind.

This choice will dictate what circuitry you'll need. For example, to transmit digital data using Bluetooth, several complete modules are available. BlueSmirf is one available from SparkFun.

An MCU can perform the ADVZ function as well as communicate with the Bluetooth module to transmit the data.

There is coding to be done. Have you coded?

Then how are you going to receive it?

Another Bluetooth module and another MCU. You could then write the code to display on an LCD. Obviating your voltmeter. Or are you set on reading the voltage with your voltmeter?
 

shteii01

Joined Feb 19, 2010
4,647
The easy way.
1. Hook up your 5 volt sensor to Arduino Uno. Why Uno. Because Uno has 5 volt ADC. It will take your 0-5 volt sensor readings and covert them into digital values 0-255. The software is free.
2. Hook up bluetooth or wi-fi "shield" to Uno, there are a dozen or more of them, and there software already written and tested and known to work just fine. And software is free.
3. Configure your receiver (phone, pc, whatever) to receive.

Once you get something like this to work. Then you can start working out what your task specific device would need and don't need.
 
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