Sunday, January 11, 2009

Another darned *Duino!

UPDATE:   This Arduino clone no longer seems to be available and the links below are now dead. I leave this up here for historical background. Also, the hookup to a USB adapter is still valid for other "Duinos without a USB port.

Just a short post to document my most recent acquisition, which is yet another form factor/variant of the Arduino, this time the DuinoStamp. This is a small, breadboardable version of the Arduino which is described at and orderable from Fundamental Logic (click here to go to their order page). It cost less than $10 for the kit, so I went crazy and ordered four just to have a stock of spare ones.

This comes as a very straightforward kit that takes all of about 15 minutes to solder up. Here is what it looks like all done up on a breadboard:

This is a very basic *Duino that doesn't include a built in USB interface (similar to the Arduino Mini, but a bit bigger). You therefore need to rig it up to an external USB to TTL serial converter, which is where I ran into a minor hiccup.

The problem is that on the new model Arduinos, they load up software very nicely and you don't need to do anything special, but with the older Arduino models you need to fiddle with the reset button at the exact right time to get them to upload new firmware. This is initially how I thought you had to use the DuinoStamp, but it was very frustrating trying to figure out the exact right timing for the reset and an error message that looks like:

avrdude: stk500_getsync(): not in sync: resp=0x60 avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x66

(Whoever "Avrdude" is?). Anyway, I dropped a note to the Fundamental Logic people and Kevin got back to me right away and said the trick is to put a 0.1 uF capacitor between the RST pin on the DuinoStamp and the DTR pin on the USB adapter. Here is a rather crude scheamtic (click for full size):

So, now I can upload new firmware to the StampDuino, I shall try to port over some of my other projects to this new form factor.

Next up, I need to start describing my Xbee sensor network!

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