Arduino Shields Compatibility list: share your experiences

Discussion in 'General Discussion' started by mikelangeloz, Apr 29, 2014.

  1. mikelangeloz

    mikelangeloz Member

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    In order to help people to undertand if their Arduino Shields can be operated with UDOO, and if there is some "gimmicks" needed to make it work, please share here your experiences.
    As we collect informations about working Arduino shields we'll update this topic, giving some kind of reference and a sort of compatibility list. Please keep this thread clean, post just the Shield you've used, if it was working straight away or if you needed some extra trick, no OT please...
    Let's start!

    Arduino Motor Shield: Working, no additional operations needed
     
  2. m3m3nto

    m3m3nto New Member

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  3. francescomm

    francescomm Member

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    Re: Arduino Shields Compatibility list: share your experienc

    For the joystick shield, there is a fix that must applied to the shield itself (cut 5V pin line and solder to 3V pin)

    joystick-shield-t1164.html

    If there is a fix that makes it compatible with both I would like to know.

    I would be interested to know about the following shileds:

    • motor shield - I have seen it used on the totorials, is it totally safe?

      kinkerkit - lots of nice sensors, how to reduce them to 3.3V?

      xbee - is that ok or must be fixed too?
     
  4. ariosa

    ariosa New Member

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    Re: Arduino Shields Compatibility list: share your experienc

    I purchased an LCD button shield (http://i.imgur.com/BBMMYFd.jpg), with the hopes of attaching it to my UDOO. I'm a novice when it comes to using Arduino devices, so I'm not sure if the device I purchased is going to output a voltage which is unsafe for my UDOO. It takes in power of 5v, and uses the analog input pins to carry a voltage to the board. I am a bit concerned when I read about the potential for the UDOO to burn out if receiving above 3.3 volts, and was wondering if there was a "fix" to prevent my UDOO from being damaged. The schematic for the shield is here http://i.imgur.com/fi7eZDy.png and it appears to have only one button which triggers an output higher than 3.3v (the select button at 3.62 volts) I am comfortable with soldering and attaching resistors, and I have seen the post regarding UDOO's compatibility with 5v devices and how to install resistors. I am still confused as to which pins and in what arrangement I would need to attach my resistors in order to make sure I am safely connecting this device, or if I could use a simple fix like the joystick shield compatibility fix mentioned above.
     
  5. mkopack

    mkopack Member

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    Re: Arduino Shields Compatibility list: share your experienc

    Ariosa: You should be fine with the button portion, since a button just shunts (or lets through) whatever power is provided to the input side out to the output side... (ie, buttons don't know if it's 3.3V, 5V or 200V). HOWEVER, you need to change where in the diagram it says to hook to the 5V, and hook up to the 3.3V instead. (ie, cut the trace to the 5V pin, and solder in a wire to jump that trace over to the 3.3V pin instead.

    The LCD might be the issue though. Without the diagram I can't tell, but it might expect to be driven through 5V power and 5V signalling, which the udoo won't do directly (the signalling). Do you have a link to the actual shield in question?
     
  6. ariosa

    ariosa New Member

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    mkopack: Thanks for your response! I see this is the same fix that was applied to the joystick shield, and it seems like a good solution! The link to the shield I purchased is here: http://www.dx.com/p/2-6-lcd-keypad-shie ... 8QJmvldXHU

    I know its a cheap Chinese manufactured shield with little to no documentation -__- so I'm not going to be heartbroken if it does not work at 3.3 volts, but I'll definitely give that solution a try once I get my UDOO and the shield (still waiting for it to show up in the mail)
     
  7. fetcher

    fetcher Member

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    Re: Arduino Shields Compatibility list: share your experienc

    That LCD looks like a common HD44780-type, which needs 5V power on its Vdd pin (and to one side of the contrast adjustment dial), but works fine with 3.3V signals. I use one on my Udoo (driven from i.MX6 GPIO's) without any problems. You'll just need to split the power rail, running 3.3V to the buttons and 5V to the LCD. Its backlight (A & K terminals) would work on either, but will be brighter at 5V. If you want 5V, make sure the negative terminal there isn't connected to a switched pin... or else add a transistor to drive it. A simple 2n2222/2n3904 w/ 1k base resistor to the control pin works fine (but may come on when its driving pin is floated, e.g. set to input). At 3.3V, a direct connection may work, although Udoo/Due pins can't sink as much current as the 5V AVR's can. Hardwiring the backlight to power & ground (w/ series resistor if needed) so that it's always on would be the easiest solution. Your shield may do that already.

    One more thing to be careful of-- make sure the LCD's RW pin is tied to ground, so that it's locked into "read" mode and will never try to send any data back to the Udoo (transmitted data would be at 5V levels). This is almost always the case when this type of LCD is used with an Arduino or other small microcontroller-- there isn't much use for reading out screen contents or status, and R/W just wastes a pin (often in short supply on smaller Arduinos), but check it with an ohmmeter to be sure.

    I did notice a strange quirk after hooking up my HD44780 LCD, where the Udoo would no longer shut down into halt/soft-off state (shutdown -h now), but immediately reboot itself instead. Apparently minor current leakage coming back via control pins, from the LCD's unswitched power supply was enough to confuse the i.MX6's power control section. This was only a minor annoyance, and since I'm using the watchdog timer now I can't halt the machine for very long anyway, but interestingly, adding a 3V coin cell to the Vbat terminal (intended to keep the real-time clock running) stopped this from happening. I guess it helped to stablize the i.MX6's Vdd_SNVS rail.
     
  8. S.Arnold15

    S.Arnold15 New Member

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