Category: Arduino

Success!

16. July 2010 13:36 by Jens Willy Johannsen
Categories: Arduino | Telit GE865

I connected everything – that is: battery, SIM card, push button, LED and transistor and level shifting for 2.8V <-> 5V logic. And considering how much trouble people seem to have had I was surprised how quickly it worked!

The only two things I ran into was:

  1. The first SIM card I used didn't want to talk to the GE865. Probably because it is for a 3G modem and not a phone. Anyway, the second (normal) SIM card worked perfectly.
  2. Using the Arduino IDE's serial monitor as terminal interface didn't really work. But using "screen /dev/tty.usbserial-A9007ND2 9600" from the Terminal prompt worked flawlessly.

I had zero problems with the power supply. Even though I'm not using the recommended low ESR capacitor. Maybe because I'm in a densly cell-phone-covered area. Or maybe because the battery is capable of delivering up to 2A by itself.

And everything worked: sending and receiving SMS'es, retrieving a web page using GPRS. Nice! Now I just need to connect it to a DTMF decoder and a Speakjet :-)

Here's a picture of the breadboard setup:

(click to view large version)

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Keep it simple

8. July 2010 15:49 by Jens Willy Johannsen
Categories: Arduino | Telit GE865

– at least to begin with.

I have received the stuff (from Lawicel in Sweden since they had everything in stock) so let's fire it up...
Having read about how many problems can arise with these modules, I have decided to try out a simple-simple test first.
That means connecting the GE865 to a 1000 mAh LiPo battery (without the low ESR cap which I haven't received yet), connecting a manual push button on the on-off pin and a LED to the status LED pin (and a SIM card, obviously).
And then use the Arduino's serial monitor to send and receive commands.
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“ET phone home…”

4. July 2010 15:33 by Jens Willy Johannsen
Categories: Arduino | Telit GE865
When SparkFun had a SM5100B module on sale I thought it would be fun to make some sort of device that can provide feedback by way of a cell phone.
But having looked around a bit most people seemed to recommend skipping the SM5100B in favor of one of the Telit modules (GM862, GE864 or GE865). Apparently, the Telit modules have better documentation and there are more information about projects using those. Unsurprisingly, they are also more expensive...
Both the GE864 and GE865 needs an external SIM card holder. The GM862 has an internal SIM card holder and also includes a GPS (there is also a non-GPS version).
Most projects out there seem to use the GM862, but I settled on a GE865. The reasons: it's cheaper and smaller due to its having fewer connection pins (most of which I won't use anyway).
There are a few issues to pay special attention to when using this module (or any of the other Telit modules). Two main concerns are: 1) power supply and 2) logic levels
  1. Power supply
    The power supply is ciritial. Firstly, the module requires 3.8V (will accept 3.4V - 4.2V). Secondly, the power supply has to be able to supply 2 Amps in peaks. This is way more than most simple power supplies can handle. This seems to be the single most common source of problems people have when the module does not work properly.
    I will power the module from a single 3.7V LiPo battery. The hardware guide recommends a battery capacity of 500-1000 mAh in order to handle an output of 2A. Therefore [this] battery looks ideal.

    In order to handle the current spikes a capacitor must be fitted. It is crucial that the capacitor is a "low ESR" type. The hardware guide recommends a 100 µF 10V tantalum capacitor.

  2. Logic levels
    The module uses 2.8V CMOS logic levels. That means that logical high is nominally 2.8V (specified as between ~2.2V and 3.0V). This is different from the ATmega168 levels where output high is close to Vcc (required input high when supplied at 3.7V is ok at approx. 2.0V).
Off to click the "put in basket" button a few times...
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TextMate Bundle for Arduino 0017

17. November 2009 16:07 by Jens Willy Johannsen
Categories: Arduino

TextMate Bundle to build and upload Arduino sketches

Far be it from me in any way, shape or form to criticize the Arduino IDE which is simple, easy to use and works flawlessly (at least I have never had any problems). However, there are times when I find it preferable to write the Arduino sketches in TextMate (which is the text editor for Mac, in case you didn't know) since it has better... well, text editing functions. Until yesterday I frequently wrote/edited the sketches in TextMate and then copied the text over to the Arduino IDE in order to upload the sketch.
There are several guides on compiling and uploading from the command line and also several TextMate bundles for doing this but I couldn't get any of them to work on my setup (Mac OS X 10.6.1, Arduino Duemilanove and Arduino 0017) so I had to hack one together myself using bits and pieces from the other available bundles and documentation from various forums.

Here it is: TextMate bundle for Arduino 0017

Assumptions
This bundle assumes that the Arduino IDE version 0017 is installed in /Applications and it named "Arduino". If this is not the case you need to change a path in the makefile (refer to the section about messing with the Makefile).

How to use it

  • Extract the zip and double-click the .tmbundle file to install it in TextMate (which, of course, you will need to have installed beforehand).
  • Create a new document in TextMate, write some Arduino code (or copy/paste in the sample Blink code) and save the file with a .pde extension
  • Hit Cmd-R to compile and upload the sketch

You can also hit Cmd-B just to compile without uploading (to check your syntax).

Note that a folder named "applet" will be created in the same location as the .pde file during compilation. (You can delete it if you want or leave it in place.)

MCU and F_CPU settings
The Makefile needs to know what AVR processor and which clock speed to compile to. The defaults are ATmega328 and 16 MHz (i.e. a standard Arduino Duemilanove).
These values can be overridden by setting other values in TextMate's preferences. In the TextMate preferences, choose the "Advanced" tab and click "Shell Variables". Add the following variables to override the default values:

Variable Value
TM_ARDUINO_MCU atmega328p|atmega168|...
TM_ARDUINO_F_CPU 16000000|8000000|...

For example, the following settings will compile for an ATmega168 running at 8 MHz:
TextMate preferences

If one or both of the above variables are deleted or disabled, the default values will be used.

Messing with the Makefile
If you need to change something in the Makefile (e.g. the path to the Arduino tools) go right ahead and do it.
The Makefile is located in the bundle. The bundle is located in ~/Library/Application Support/TextMate/Bundles. Option-click and choose "Show Package Contents" and then open the "Support" folder and edit the Makefile to your heart's content.

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