Eleven incompatible with Yun Shield

The "Eleven" is our Uno-equivalent Arduino-compatible board, but with a number of improvements including prototyping area, a mini-USB connector, LEDs mounted near the edge, and the D13 LED isolated using a FET. [Product page]
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Eleven incompatible with Yun Shield

Post by dqmcdonald » Thu Sep 04, 2014 2:11 am

Hi Forum Folks,

I'm a big fan of the "Eleven" and all "Freetronics" products and generally use them in preference to other models. I have noticed an apparent incompatibility specific to the Freetronics Eleven and it might save somebody else some time to record it here. This arises with the use of the Yun Shield, from Dragino:

http://www.dragino.com/products/yunshie ... hield.html

This shield allows uploading of scripts via WiFi, rather like the Arduino Yun itself but allowing the use of (practically) any Arduino. When I got my shield recently I found I could get it powered and connect to it via WiFi but I could not upload sketches to the Arduino over Wifi. The error was avrdude failing with:

Code: Select all

avrdude: AVR device not responding
avrdude: initialization failed, rc=-1
After a bit of back and forth with the tech support folks from Dragino I ended up removing Q2 (the MOSFET that drives the LED attached to D13) from my "Eleven" board. Once I did that the Yun shield worked. Therefore it seems there's something especially sensitive about the Yun shield and the FET/LED on pin 13 (which is also SCK for SPI) which is enough to prevent the Yun shield from being able to program the Eleven via SPI.

I have used a number of other SPI devices with my Eleven and never noticed anything anomalous. So it seems this particular shield, or the application of programming the Eleven via the ICSP pins, is especially sensitive.

Note that the Dragino Yun Shield also requires the reset of the ATMega8U2 to be tied to ground to disable that device. That's done reasonably easily by soldering a couple of pins onto the USB ICSP and bridging those with a jumper. This is also required for a genuine UNO so not specific to the Eleven.


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Re: Eleven incompatible with Yun Shield

Post by andrew » Sat Sep 06, 2014 8:07 am

Interesting note, thanks for letting everyone know.

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