The ever shrinking Arduino

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The las version of Arduino I bought is the micro. Around the size of the Arduino Pro Mini but
featuring a processor that handles the USB port too and costing $7.50. As I bought mine from an Asian online seller off eBay I decided to give a try before providing feedback.

Last week I have got trouble with two items I bought on Aliexpress: a set of Kossel linear rails that have rough spots along the rail and a set of hardened chromed smooth rods that are very smooth but bent too. In both cases they first impression was they were ok and I give them the heads up so they could get my money. Unfortunately, on closer inspection I discovered the problems mentioned above and I am still in the process of sorting it out with the sellers.

This time I wanted to be quite sure everything worked as expected ... but it did not. I could happily upload new sketches once I selected the Arduino Micro as the target board. But I could not get Blink program to work. After checking Arduino docs about the Micro it was clear pin 13 was actually the LED pin on it. But I had not one but two leds staying on all the time (besides the power pin).

A closer inspection revealed my unit was another variant called Pro Micro. It turned out this board does not have the led at pin 13. The two leds availables are somehow weird, as one of them is connected to RX_PIN that happens to be pin number 17 but the other led is connected to TX_PIN which, oddly enough, is not associated with a pin number, but two macros: TXLED1; will set it off and TXLED0; will turn that led on.

You can get the Blink program for that board from Sparkfun. And a micro USB cable is needed (similar to the one most Android smartphones phones use).

I am happy to report that at least this device works ok :-)

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