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Topic: WiFi Shield Problem for Mars Rover Concept (Read 522 times) previous topic - next topic

danscarfe

Hello all. :)

Forgive me if I have posted in the wrong section - this is my first post.

Let me introduce myself... My name is Dan, and I work for Astrium, an aerospace engineering company who mainly produce satellites. We are the largest space company in Europe & 3rd largest in the world.

I'm a second year apprentice, and we have been set a task to create a Mars rover concept vehicle by the 11th of October, ready for INTECH Science Fair during World Space Week. There are 6 of us in our team, and I am in charge of the programming side of things. Other than previous experience with HTML, CSS & PHP I have little to no programming knowledge, but I'm willing to learn.

I'm going to give away a few secrets now, but we've decided to use Arduino as part of the concept vehicle. It's not going to be driving the vehicle, but rather reading a large variety of sensors and then relaying back. It should hopefully attract a lot of attention. So far so good - we have the sensors working, but this obviously requires the Arduino to be plugged into a computer at all times to read from the serial monitor. This isn't practical as the rover is going to be moving and away from a laptop, so...

We decided we'd make use of the WiFi shield and create our own webpage that people can view the sensor readings on at the science fair (we will have a laptop connected to it at all times). This is where I ran into problems. I can get the WiFi shield to sort of work. It connects to my WAP network at home just fine, and states its MAC address and IP.

But when I try to connect to the IP, Chrome states 'cannot connect'. I can ping the address so it obviously exists. I have tried several browsers, to no avail. A lot of people said to downgrade the IDE and it will work, but unless you need to do a clean install that's not working for me either. Dragging the app to the trash obviously doesn't remove all files so I wondered if that may have something to do with it..?

I am using an Arduino Mega 2560, Official Arduino WiFi Shield, & a MacBook running OS X 10.7

So what now? Do I need to upgrade the firmware on the WiFi shield or Mega, is that my only option? I can't understand why it's not working. This is one of the last things we need to do but unfortunately crucial to the whole project! :(

Thank you for your help,
Dan

PaulS

First, I think that WiFi is the wrong choice. The Mars Rover really won't be communicating with a WiFi server on Earth. Using something, like XBees, that more closely mirrors what will really be used would be (or have been) a good idea.

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we will have a laptop connected to it at all times

It? What is it? The WiFi shield does not allow connecting to a PC. It allows connecting to a WiFi router. Clearly, the WiFi router doesn't go on the rover.

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A lot of people said to downgrade the IDE and it will work, but unless you need to do a clean install that's not working for me either.

"That's not working" is simply too lame to bother replying to. You have emptied the trash, right?

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It connects to my WAP network at home just fine, and states its MAC address and IP.

Getting it to connect to the WiFi router at the demo sight would be more useful, wouldn't it?

zoomkat

If you need something simple and fairly quick, you might check the below. Simple setup that uses an arduino with a w5100 Ethernet shield and a common wireless router. You can connect an IP cam to the router for video feed, and use a web page as the control interface.

http://www.lynxmotion.net/viewtopic.php?f=20&t=6343
Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

MattS-UK

#3
Sep 29, 2013, 01:52 pm Last Edit: Sep 29, 2013, 02:02 pm by MattS-UK Reason: 1

Let me introduce myself... My name is Dan, and I work for Astrium, an aerospace engineering company who mainly produce satellites. We are the largest space company in Europe & 3rd largest in the world.


Hi Dan,

I am principally a network engineer, been using the wi-fi shield for a few months....and not so far away from you.

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We decided we'd make use of the WiFi shield and create our own webpage that people can view the sensor readings on at the science fair (we will have a laptop connected to it at all times).


An immediately attractive idea but one with a mass of headaches.  

The biggest issue you have is the lack of runtime and RAM available to your Mega.  HTTP is a loose (vague) protocol.  Decoding the protocol is relatively costly, as the host (server) must parse many strings of indeterminate length, within multiple contexts.  Arduino developed and just released the Yun because it is such a big ask for an M/C to do on it's own.  Alternatively, I have been experimenting with a Beaglebone Black for a few months, achieving a roughly similar, single board sensor/web server solution.

I concur with PaulS and XBee would be a much better choice of wireless protocol for your use case - longer range, lower power, fewer dependancies.  

Given how little time you have, there may be a half way house using what you have and what you can download.  Design things so the robot sends no more than it needs to send, and the laptop does the heavy lifting of processing and presentation.

1. Utilise the Wi Fi shield on the robot.
2. Run a web server on your laptop.  A laptop has more than enough CPU and RAM to run IIS, Apache or lighttpd, freeing you from developing your own HTTP parser.
3. Connect the robot to the web server by writing a simple receiving application which will run on the laptop.  It just needs to be able to access the IP stack, assemble a web page and write it into the web server file space.  
4. Implement a simple proprietary protocol for sending the sensor readings over a Sockets interface (UDP or TCP by any other name).  

Personally, I would write the receiving application using Xojo (Real Basic / Real Studio in a former life).  A BASIC like, cross platform OOP language, which runs on Mac, Windows and Linux, compiles to machine code, and comes with some ready to roll Sockets classes.  It should be a cinch for anyone with an ounce of programming skills to pick up the syntax and write a simple server.  Xojo is proprietary but you can download the demo for free.

For the protocol choice, I would go with the lower overheads of the uncompelled UDP.

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So what now? Do I need to upgrade the firmware on the WiFi shield or Mega, is that my only option? I can't understand why it's not working. This is one of the last things we need to do but unfortunately crucial to the whole project! :(


You may have more than one problem!

The Wi Fi shield is not without it's issues.  Barring hardware fault/failure, the WiFi shield will indeed (just about) work but the firmware version must match the version of Library code used by the IDE.  So, to find the right WiFi shield firmware files (on a Mac)
1. Download the latest 1.0.5 arduino.app and install to your /Applications folder as usual
2. Open finder, select Go to folder and enter /Applications/arduino.app/Contents
3. Navigate down the folder tree to Resources/java/hardware/firmwares/wifishield
Keep in mind WiFi shield firmware flashing is a two stage process.  There are two controllers on board, one looking after the WiFi, while the other communicates with Arduino.

Will the firmware fix your Chrome issue?  I doubt it.  

The example web server code has a HTTP semantics issue going on. The server code declares a HTTP1.1 response, then goes and implements a HTTP1.0 response.  The resulting browser behaviour falls into the 'undefined' catch all.  Some browsers will accept the response, others (Chrome) reject it as non-compliant garbage.

HTH.  Good luck with the competition.


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