Advisory for Wink and Ringo Robots
Robots getting Hot, Prevention
Several users have now reported a problem where their Wink or Ringo robots become hot, and occasionally stop functioning. This problem has been rare with only a few reports over the past year. We have now been able to identify the exact cause of the problem. In this article we provide a solution that will prevent this problem from being able to occur.
WE RECOMMEND THAT ALL OWNERS OF WINK OR RINGO ROBOTS MAKE A SIMPLE MODIFICATION TO THEIR PROGRAMMER BOARDS AS DETAILED BELOW. BY CLIPPING TWO PINS FROM THE PROGRAMMER, YOU WILL ELIMINATE THE POSSIBILTY OF THIS PROBLEM OCCURING.
Background:
This problem occurs when the ribbon cable is connected to the robot incorrectly. The incorrect connection allows power to flow in the reverse direction through the part on the robot that manages charging of the battery. This reverse current can cause the part to become hot to the touch. Once the ribbon cable is removed, the battery may then begin to discharge slowly through the now damaged part which may keep the part hot for several minutes. The robot may or may not continue to function afterward.
When we designed the robots, we took into account that users may connect the ribbon cable upside down. If the user connects the ribbon cable upside down, nothing bad will happen (except of course the robot will not program until connected the correct way).
However, if the ribbon cable is connected upside down AND AT THE SAME TIME it is only connected to the top row of pins on the robot, the contacts will be aligned such that this reverse current situation exists. So it does require two connection errors to be made at the same time, though it is understandable that especially in classroom environments, this will inevitably happen on occasion.
NOTE: Some people assumed the heat was caused by running code (for example running the motors too long, etc). We should point out there is no way to damage the robot by running code or "incorrect" code or anything like that. We designed the robots to be robust and in all cases we are aware, it would be impossible to damage a robot by running the robot too long or running the wrong code, etc.
Also note that there are two circuits on the robot that actively prevent any sort of over current during normal use. There is a part on the robot that electronically limits current to the motors, eyes, LEDs, and other parts that may actively draw current. This part is designed to maintain an endless short circuit event without damage, and restore normal operation as soon as a short is cleared. We have tested this many times and it always works great. In addition to this, the battery tab includes a resettable fuse inside that will automatically open if more than about 300 milliamps are drawn from the battery (for example if the battery tab was directly shorted on the bottom of the robot). Normal operation is restored automatically about a minute after the short is cleared.
So other than this specific case where the ribbon cable is connected in an unexpected orientation, the robots are solid and you should feel confident experimenting and allowing your students to experiment without fear of causing any damage.
Prevention on Future Wink & Ringo Robots:
We are now shipping all orders with the key pin on the programmer already clipped (see below) so it will be a non-issue going forward.
We are also happy to announce we will be releasing a Wink2 and a Ringo2 in the very near future (expected available about February 2017). The new robots will be identical to the original Wink and Ringo, except we are now moving the functionality of the programmer board directly onto the robot itself. This will eliminate the need for the programmer board and ribbon cable altogether. The cost will be the same.
We have listened closely to feedback over the past year and almost all issues we've encountered are related to the ribbon cable. With this new version, the user will simply connect the USB cable directly to the robot. It was a tight fit to get the programming hardware on the robot but we made it happen. We had originally made the programmer board separate so advanced users could connect more sophisticated debugger hardware. However, in practice this is quite rare and the confusion with ribbon cable connections has been far more prevalent.
Modification for Existing Users:
For all users (except advanced users, see note below), we suggest making the following modification to your programmer board.
WE RECOMMEND THAT ALL OWNERS OF WINK OR RINGO ROBOTS MAKE A SIMPLE MODIFICATION TO THEIR PROGRAMMER BOARDS AS DETAILED BELOW. BY CLIPPING TWO PINS FROM THE PROGRAMMER, YOU WILL ELIMINATE THE POSSIBILTY OF THIS PROBLEM OCCURING.
Background:
This problem occurs when the ribbon cable is connected to the robot incorrectly. The incorrect connection allows power to flow in the reverse direction through the part on the robot that manages charging of the battery. This reverse current can cause the part to become hot to the touch. Once the ribbon cable is removed, the battery may then begin to discharge slowly through the now damaged part which may keep the part hot for several minutes. The robot may or may not continue to function afterward.
When we designed the robots, we took into account that users may connect the ribbon cable upside down. If the user connects the ribbon cable upside down, nothing bad will happen (except of course the robot will not program until connected the correct way).
However, if the ribbon cable is connected upside down AND AT THE SAME TIME it is only connected to the top row of pins on the robot, the contacts will be aligned such that this reverse current situation exists. So it does require two connection errors to be made at the same time, though it is understandable that especially in classroom environments, this will inevitably happen on occasion.
NOTE: Some people assumed the heat was caused by running code (for example running the motors too long, etc). We should point out there is no way to damage the robot by running code or "incorrect" code or anything like that. We designed the robots to be robust and in all cases we are aware, it would be impossible to damage a robot by running the robot too long or running the wrong code, etc.
Also note that there are two circuits on the robot that actively prevent any sort of over current during normal use. There is a part on the robot that electronically limits current to the motors, eyes, LEDs, and other parts that may actively draw current. This part is designed to maintain an endless short circuit event without damage, and restore normal operation as soon as a short is cleared. We have tested this many times and it always works great. In addition to this, the battery tab includes a resettable fuse inside that will automatically open if more than about 300 milliamps are drawn from the battery (for example if the battery tab was directly shorted on the bottom of the robot). Normal operation is restored automatically about a minute after the short is cleared.
So other than this specific case where the ribbon cable is connected in an unexpected orientation, the robots are solid and you should feel confident experimenting and allowing your students to experiment without fear of causing any damage.
Prevention on Future Wink & Ringo Robots:
We are now shipping all orders with the key pin on the programmer already clipped (see below) so it will be a non-issue going forward.
We are also happy to announce we will be releasing a Wink2 and a Ringo2 in the very near future (expected available about February 2017). The new robots will be identical to the original Wink and Ringo, except we are now moving the functionality of the programmer board directly onto the robot itself. This will eliminate the need for the programmer board and ribbon cable altogether. The cost will be the same.
We have listened closely to feedback over the past year and almost all issues we've encountered are related to the ribbon cable. With this new version, the user will simply connect the USB cable directly to the robot. It was a tight fit to get the programming hardware on the robot but we made it happen. We had originally made the programmer board separate so advanced users could connect more sophisticated debugger hardware. However, in practice this is quite rare and the confusion with ribbon cable connections has been far more prevalent.
Modification for Existing Users:
For all users (except advanced users, see note below), we suggest making the following modification to your programmer board.
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1) Remove the ribbon cable from your programmer, and disconnect the programmer from your computer.
2) Clip off the two pins shown in red. These pins are fairly easy to clip. If you don't have a small pair of snips, you can also use common fingernail clippers to remove the pins. You do not have to cut them completely flush with the plastic piece. As long as they are close, they will no longer make contact inside the ribbon cable connector, which is what we want. 3) Replace the ribbon cable back onto the programmer with the same alignment it was originally. As the two pins are now missing, be sure to connect the ribbon cable correctly (not shifted over one pin). That's it. This change will have no other effect on how the robot operates or programs. These pins are only used by more advanced debuggers (such as the Atmel AVR MkII Programmer). We use these advanced debuggers for testing and installing the bootloader during production, but end users have no use for these pins. If you are an advanced user and wish to maintain the ability to use these advanced programmers, see the Advanced Users Only note below. |
Advanced Users Only:
If you are an advanced user and you plan to use an AVR MkII or similar programmer/debugger, you should only clip one of the pins. The pin on the top is a "target voltage reference" used by the programmer to match voltage of the target board and is required to allow the AVR MkII to function. The bottom pin is the one we're really after here. (It is a secondary ground pin, which once removed, prevents the reverse current). For most users, we suggest clipping both because getting at the bottom pin is difficult without first removing the top pin. If you do wish to maintain functionality of additional programmers/debuggers, only clip the bottom pin. It's tricky but possible. You may have to bend it outward with some tweezers or small needle nose before you can reach it with a cutting tool. If the top pin is bent in the process it can usually be straightened easily enough.
If you are an advanced user and you plan to use an AVR MkII or similar programmer/debugger, you should only clip one of the pins. The pin on the top is a "target voltage reference" used by the programmer to match voltage of the target board and is required to allow the AVR MkII to function. The bottom pin is the one we're really after here. (It is a secondary ground pin, which once removed, prevents the reverse current). For most users, we suggest clipping both because getting at the bottom pin is difficult without first removing the top pin. If you do wish to maintain functionality of additional programmers/debuggers, only clip the bottom pin. It's tricky but possible. You may have to bend it outward with some tweezers or small needle nose before you can reach it with a cutting tool. If the top pin is bent in the process it can usually be straightened easily enough.
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Advanced users who wish to maintain the ability to use other programmers/ debuggers like the AVR MkII should only cut the bottom of the two pins as shown. |
Helpful Suggestion (Especially for Classroom Use):
Once the modification in this note is complete there will be no further concern of a user damaging the robot. However, students can still easily connect the ribbon cable upside down and require assistance when the resulting connection fails to program the robot. We suggest teachers make a mark on the top side of both ends of the ribbon cables. You can then instruct the students to make sure the mark is facing upward when connecting to the robot. A similar method is to make a red mark on the bottom of the cable and a green mark on the top of the cable and note they should always see green when connecting the cable. We find Sharpie markers work well and are not easily rubbed off the ribbon while handling.
Once the modification in this note is complete there will be no further concern of a user damaging the robot. However, students can still easily connect the ribbon cable upside down and require assistance when the resulting connection fails to program the robot. We suggest teachers make a mark on the top side of both ends of the ribbon cables. You can then instruct the students to make sure the mark is facing upward when connecting to the robot. A similar method is to make a red mark on the bottom of the cable and a green mark on the top of the cable and note they should always see green when connecting the cable. We find Sharpie markers work well and are not easily rubbed off the ribbon while handling.
Add marks to the top side, both ends of cable for easy identification and proper alignment.
Robots that have become Damaged:
If you have a robot that you believe may have been damaged due to this problem, please contact us via the Contact form on this website and we will coordinate with you for a repair. The damaged part is easy for us to replace and we'll have you up and running again quickly. We very much value our customers and want you all to have a great experience. If you're comfortable doing small surface mount soldering yourself, we can also send you the part and you are welcome to replace it yourself. Thanks!
If you have a robot that you believe may have been damaged due to this problem, please contact us via the Contact form on this website and we will coordinate with you for a repair. The damaged part is easy for us to replace and we'll have you up and running again quickly. We very much value our customers and want you all to have a great experience. If you're comfortable doing small surface mount soldering yourself, we can also send you the part and you are welcome to replace it yourself. Thanks!
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