Networking & Wireless forum


need help with wifi project

by user00789 / April 6, 2012 6:15 AM PDT

Hi guys, I'm working on a wifi controlled device project, and have some questions I was hoping you could help
me out with.

basically, I have a device that is acting as a web server, that I need to control/communicate with using an
external wireless device(smartphone/tablet). This UI on the external device has to be as robust and lightweight
as possible, running on all wifi devices without having to download an app or anything like that.

The plan I have right now is to hook up a wireless router to the server, and set up a captive portal that
leads to a webpage hosted locally on the server, that acts as the UI in the external device's web browser.

If that is indeed the best solution, I have questions about the setup:

which hardware should I use? It must be less than $40, preferably less than $30. Range is not an issue, in fact
I'd like to contain the range of the signal to less than a few meters, so I'm probably going to use my own
antenna, also must support openWRT or tomato, I've heard bad things about DD-WRT.

Do I need to worry about how much flash/ram the device has? This will not be used to access the internet or
anything major, ONLY to load this one webpage UI from the primary device/server and talk to the primary

So far the following two seem like something I'm after:

the ASUS RT-N10+ is $30 on newegg, and the TP-LINK TL-WR740N is $25 on newegg:

Also, which firmware should I use? Right now I'm in between openWRT and tomato. I think both are capable of
what I want to do, so this mostly depends on which supports the hardware I decide on.

Lastly, which captive portal solution should I use? I don't think I need any authentication or authorization,
any device should be allowed to connect. I started out looking at wifidog, but it seems like that's more than I
need for just redirecting all traffic to the local server's page, and I'd like to avoid having to run a RADIUS.
With this in mind I was considering something like nocatsplash.

Any suggestions at all would be greatly appreciated, thanks for your time.

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Clarification Request
I'm a bit unclear.
by R. Proffitt Forum moderator / April 6, 2012 6:31 AM PDT

When I do such projects, I rarely have to limit my budget to 30, 40 bucks because it's ONE PROJECT and the time I spent fussing with a 10 buck less box is blown far too quickly. Something's not being told here. 10 bucks can't be the end of the project?

As to which firmware, you use the one the you are able to work with and fits the router.

Also unclear is how much work you've done in this area. Read

Now is this you trying to get it right the first time? The perfect device/app by taking the class, notes and thinking you can do this without a lot of practice? You may want to work on this many times to figure it out.

Here's an open source wifi controlled hardware thing ->

So with all that said, maybe what you are doing is just a plug and play thing?

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by user00789 / April 6, 2012 7:24 AM PDT
In reply to: I'm a bit unclear.

R. Proffitt, first of all, thank you for your reply!

The reason for the cost constraint is that this is a prototype project that could possibly be mass manufactured in the future.

With respect to your book reference, that seems like an excellent book and the message makes sense to me, after all, practice makes perfect.

I'm not trying to get the whole project right the first time, that would be a nightmare if I had to debug (incremental approach FTW). I am however trying to get the purchasing of the hardware right the first time, I don't want to waste money.

I guess what I am really asking is what hardware I should buy, while also probing for better solutions than the one I have planned.

Once again, thanks for your reply!

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" The reason for the cost constraint is that this is a
by R. Proffitt Forum moderator / April 6, 2012 7:39 AM PDT
In reply to: re:clarification

" The reason for the cost constraint is that this is a prototype project that could possibly be mass manufactured in the future. "

Sorry but as a designer that has been down that road many many many times you've lead with a common misconception. First you get it working, demo it and then cost reduce it.

If you lead off with cost, you've lost almost any chance of demonstrating your concept to obtain the next round of funding for the cost reduction phase.

Since I know so little of your project I am left to write about lessons I've learned over the years.

--> What is this issue with wasting 20 to 30 bucks to get to mass production?

I've seen that happen as well.

Have you thought of a Raspberry Pi stick for the I/O (25 bucks) and then for the wifi, some router till you get the Raspberry Pi WiFi working?

--> How much embedded design have you done? I started in the late 70's so I have worked on most systems over the years.

I know you may not want to tell enough to reveal what's up but I can assure you that most things have been done and the idea of an IP control link page to control hardware is well, very well done. I think the first time I did that was early 90's. Later we moved to using a web browser.


All Answers

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Let's say we've been here before?
by R. Proffitt Forum moderator / April 6, 2012 7:54 AM PDT

I know the design where we connect to some wifi hotspot and get a captive site with just the web page or app.

It failed for many reasons so I'll share what does work and seems more acceptable to more users.

Go ahead and get your robot/webcam/device on the internet but instead of direct connection to the device your device checks into your web site for what to do next or to report status. Now you can get to your product from any of the usual smart phones or internet pc/apple things.

Your devices can have device IDs so it scales up nicely. There's more but with most folk challenged to connect to a hotspot, your hotspot is going to upset most "users."

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