Question on EMX and Wifi


I am going to be porting over a windows XP app to .net micro. It connects to a website via http and downloads data into an excel file. It also finds the wifi network and connects to it.

I was wondering if I purchased the GHI EMX Module, would I use the RS9110-N-11-21-01 WiFi module to be able to make this happen? Also are there any alternatives to RS9110-N-11-21-01 WiFi module. I need long distance and small/low power.

Thanks in advance,


As an alternative you can buy any FEZ (I don’t recommend USBizi for this application because of memory constraints, but it should work) and connect those to it:

The easiest way would be to chose a Gadgeteer board and use the adapter:

I know how the first module works and it can do what you expect - scan networks, connect, send/receive data, low power. The problem is the drivers are not yet developed but are expected any some time soon here: We already have the module but don’t have enough time to write the driver (you can help if you like). I know nothing about the second module other than it’s cheaper and people sometime bring it up. Maybe someone else could help you with it.

Xbee wifi would work but there is a very large difference between having a real wifi connection with sockets that used the internal TCP stack vs a simple wifi connection that do not have sockets and uses simply a serial port.

If using one of GHI’s premium offers like emx then redline wifi is the right choice for most needs.

Thanks for the replies, I appreciate the advice and options.

Gus, If you dont mind, just want to understand if I am on the right track here ->

Is the EMX basically the same as a .net gadgeteer board? Just less marketing? That’s what I need basically.
From this I am going get smaller and smaller GHI boards to find the best lowest cost/size that I can use.

and when you say Redline Wifi - do you mean: RS9110-N-11-21-01 WiFi module ?

It’s great to be able to communicate here, thanks and May The Source (Code) Be With You!

Related: I got the new WiFi module before the cable to attach to Cobra was available. Can’t use te mod on Hydra so is there a way for me to buy just the adapter cable or do I need to get a whole new unit?

The EMX is just a “module”. On it’s own it’s pretty, but pretty useless :slight_smile: It needs to go “in” or “on” something else to allow you to harvest it’s power.

The Cobra uses the EMX as it’s platform. The Cobra is an “OEM” form factor which means it doesn’t have lots of nice sockets to plug stuff in, but has oodles of IO pins available, but is presentable enough for polished demos or even for production.

The EMX Development System is designed as a developers all-in-one tool, that you’d typically use to develop your code on. It uses, strangely enough, an EMX module as it’s core.

The Spider is a Gadgeteer based solution, that again uses the EMX as it’s core. The difference here is that it’s highly modular, so you can rapidly prototype different combinations of devices easily.

So you have choices - and I’d suspect that chosing the EMX module on it’s own is not the right one.

If you don’t have large stockpile of sensors or whatever that are Gadgeteer based, then Spider has less appeal - but if you think this will become a platform you will use more, it may be a good option. If you only need a one-off and the Cobra form factor works, and you are confident in wiring up any connectors you need, then it’s a great choice too, although it may only be so in the short term as GHI have hinted at a number of upcoming releases that might affect it’s availability.

The Wifi question is then based on what platform you buy; the RS21 module if you buy spider, or the RS21 plus the UEXT header if you buy Cobra. If you don’t buy the RS21 but the module itself, you have to worry about PCBs and connections and integrating the electronics yourself.

hope that helps

Thanks Brett, you cleared a lot up for me. The EMX might be ok for me. All I need is the ability to run my .net micro app

  • which will need wifi as it will be a stand alone device.

So I figured that I would need:

  • EMX Module
  • Wifi Module
  • Power source
  • and the code

It does not have to look good. Just has to work. Does that sound do-able?

But I also feel that GHI is going to release some interesting new products. Is that the case? if so, do you know when?

Thanks again. great company!

you forgot a custom printed circuit board.

Mike, that’s what I dont get.

Couldn’t I directly solder wires to the needed terminals of the chip?

  • Power and connection to wifi module?

I am currently playing with the yellowjacket wifi/arduino nano module. And program it via usb/serial using
pins on the board.

Ok now I am starting to understand that this is a chip. But what would be on that custom circuit board?

Soldering wires to the EMX will soon turn out to be a messy. If your goal is an one time application you can make a PCB to mount the EMX SoM, the WiFi module, power supply and any other sensor or conditioning circuit.

If this is something that you are putting together for experiments and reuse you should look at the Spider.

I suggest you read the EMX user manual. You will find that the EMX module is a lot smaller than you think. Further, the EMX module is mean to be mounted on a PCB. There is no way to reliably solder wires to it.

I recommend a Cobra or a Spider.

Thanks, I need something cheaper then the spider. The spider is AWESOME for what it is. But the only thing I need it for it to do some web processing. No sensors. Only wifi So its overkill for this project. Cobra is also awesome, overkill and too much money for this particular project. If it works I will be buying many. I cant go overkill :slight_smile:

making a recomendation on this site is always difficult. :slight_smile:

if the practical EMX solutions are too expensive, wait a while for the open source solutions to mature. a hydra or Cerberus may be a more cost effective solution,

IIRC, you were talking about arduino before so why not just use cerbuino or cerberus? They are extremely low cost, much more powerful than arduino and user friendly.

All our boards are amazingly powerful and full featured but if you pick the best of the best then you need to spend a bit more :wink:

The Wifi bit is the part you’re struggling with I think. Why not go to a Wiz5100 module (Fez Connect shield) which gives wired ethernet, and then use a ethernet-wifi bridge? This would be on a platform that has lower memory, so assuming that’s not an issue (and it usually isn’t!) this might be a sensible, cheap alternative. Heres the GHI bridge that would work in this scenario:

ultimately, a custom PCB would be needed if you went EMX+Redpine board solution, and you’d need to add all the control circuitry around these modules (you could use the GHI designs as starting points, but it’s still a non-trivial exercise). In my mind, the added cost of going with a cobra board plus RS21 with UEXT connector for the first prototype would be quickly eaten up in the time it would take to think about the jigsaw alternatives that may not work; once you get past the point where your prototype and the code works you can then create the PCB design and mount your own EMX+redpine+control circuitry to it, which will keep the hardware required to a minimum (but don’t discount the fact that in quantity, the pre-built options may still work out cheaper and be supported by someone like GHI, who has years of experience making these work)

Brett, yes wifi is the issue or the Cerberus Mainboard would be exactly what I would need/want.
The Ethernet option was a good idea but its to large. Space is an issue.

And by the way I want to be clear. The GHI Products are not “Expensive” they are priced very fair and from what I read they work great. This is my issue for a specific application in an environment where the possibility of losing this equipment is very real. So it must be cheap enough to not care and very small.

Gus, my #1 solution would be the Cerberus with native wifi access and not having to deal with xbee. If I knew this was in the pipeline at GHI, I would be patient, but I have no idea and nobody is talking :slight_smile:

If I knew that using the Xbee would allow my app to connect to a wifi network, connect to a couple of my sites to get data. Then is would somewhat be an option that i can use “today” however the cost would be high. Can you tell me exactly what I would need? Starting with the Cerberus Mainboard, which xbee would I need ( I am not familiar) and also what else would I need to get this all talking together? Thanks, again, Jack

An idea, use panda with connect shield and wifi bridge we offer. You will be around $100

That might be ok in a certain testing situation for me. For live use, the size and extra power requirements would make it not a usable solution.
But as a testing ground to convert my app to .net - this might be good. Are there any limitations? Would it be able to connect to a wifi network without needing the IP?

This is going to add some complexity… and if anyone can chime in with more ideas that would be great -

I need something that is going to be able to connect to a network based on name and not need to be pre-configured with an ip. Ideally I need something that I can esily choose which network to connect to since one device will roam and need to connect to a few.