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BarkerR

Potential fix for repeating keys

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Hello there, I've managed to fix my repeat keys problem using a method I've not seen mentioned here before - changing the USB plug on the Flirc. Here's the backstory for anyone interested:

 

So, I've got two Flircs, one upstairs, one downstairs both plugged into Raspberry Pi's via a USB extension. The one upstairs has never given any issues, but the one downstairs has been a PITA from day one giving repeat keys one minute, then not responding at all the next. I tried every solution mentioned on here, clearing and reconfiguring the Flirc, changed interkey delays, changed remote controls, changed the PSU on the Raspberry Pi, removed the Wii sensor bar from the room (incase it was causing IR interference. Sometimes it would work fine for an hour, or a day then just go haywire again.

 

Tonight I was determined to get it sorted out, so I went through everything all over again, plugged the Flirc back into the Pi and it was being quite unresponsive. I put my finger on top of the Flirc to cover some of the IR sensor, tried pressing some buttons and it was working great. Awesome! I thought as I headed out to the shed to grab the black electrical tape and mask some of the IR sensor. I sat back down on the sofa and... bugger it was playing up again. I tried plugging it straight into the Pi bypassing the USB extension and then it just didn't work at all, that was until I pressed down on it. I then plugged the Flirc back into the extension, squeezed the USB connection and it was working again, released the pressure and it started playing up. Tries a different extension with the same results so I figured something must be with the USB plug on the Flirc itself. Swapped that for one from an old memory stick and voila it works perfectly now  :D

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Ok, well the flirc working after swapping the USB seems to have been a fluke and it stopped working again :( however it brought me back to putting my finger on the USB plug to get it working - here's a vid demo of that http://1drv.ms/1zc7T63 It's hard to see but at the beginning I have my finger on the USB and it's working fine (other than the sticky button on my remote). When I take my finger off it works briefly then the key gets stuck - as soon as I out my finger back on the USB the sticky key stops. Looks like some kind of earthing issue so for now I've run a wire from the Earth on my house mains and attached it to the USB which seems to do the trick.

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Maybe there is some problem with ground connection. Have you tried with different cable or even PC? Maybe the PC or the USB ports on the MoBo are not grounded properly.

 

BTW I have the same OFA URC-6440 (Simple 4) remote :).

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OK sorry I've reread the first post and you already tried changing power supply etc.

 

From what I understand (but I can be wrong) touching the ground on the Flirc can have 2 possible effects on the device: you either make better ground connection or provide additional capacitance, but I don't know how is this actually helping.

 

BTW you haven't mentioned this in your post: have you swapped both units so the one you have upstairs (the one which works properly) is plugged in the RPi downstairs?

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Maybe there is some problem with ground connection. Have you tried with different cable or even PC? Maybe the PC or the USB ports on the MoBo are not grounded properly.

 

BTW I have the same OFA URC-6440 (Simple 4) remote :).

 

I've tried it with other cables, and also plugged directly into the Pi itself with no joy. It works fine if I plug the flirc into my laptop or my Pi setup upstairs.

 

The issue is potentially my Sky TV box as things improve if I unplug the HDMI lead for that. The shielding for the satellite dish grounds to the Sky box, which is a shared ground for the HDMI so maybe it's causing some interference?

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Is any of the hardware in your setup properly grounded? All devices should share a common ground but it should also be grounded as a whole. Are your electric sockets grounded? I don't know what is the socket standard where you live.

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can you do a dmesg at the beginning of this test and at the end? Maybe that give us some clues as to what linux is seeing.

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Is any of the hardware in your setup properly grounded? All devices should share a common ground but it should also be grounded as a whole. Are your electric sockets grounded? I don't know what is the socket standard where you live.

 

I'm in the UK so the electrical sockets are grounded although I'd say none of the hardware is actually grounded in standard configuration (it's grounded now as I've wired the USB shield to ground) - TV and Sky box are on unearthed 'figure 8' leads which are only live/neutral, and the Pi runs on an iPad 5v supply. On a side note the TV on my upstairs setup (which works fine) uses a 3 pin 'kettle lead' which is grounded.

 

can you do a dmesg at the beginning of this test and at the end? Maybe that give us some clues as to what linux is seeing.

 

Yep can do, give me an hour until my daughters gone to bed (she's using the TV at the moment).

Edited by BarkerR

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Ok, well I'm totally convinced now my issues were caused by interference on the ground. Since adding an earth point the flirc has been working like a dream (and if I remove the earth it plays up again) :) 

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crazy, do you have a pic or a diagram of the setup? so a ground was added to the computer?

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crazy, do you have a pic or a diagram of the setup? so a ground was added to the computer?

 

qaA9euP.jpg

 

I soldered the earth wire to the outside of a cut down USB plug, and inserted it into the top USB port on the Pi. (excuse the dust)

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I have the same problem with repeating keys.

 

Just a very stupid idea after reading your initial post: could it be that the clear casing of the Flirc is causing some internal reflections of the IR beam which lead to the key-repeating problem? Possibly, applying pressure on the Flirc just causes more of the casing to be covered, leading to less mirroring. Normally, IR receptors are covered by a rather small, red plastic cover, possibly to prevent this to happen.

 

Also, consider that IR signals are mirrored by walls and other surfaces and the clear casing is open to signals from any direction.

 

I will try different methods of covering the sensor and report back.

Edited by Mathead

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Mathead,

Flirc casing is almost fully transparent to the IR signal so there is no possibility of signal being reflected multiple times inside the case. If material is transparent to some wavelength then it cannot reflect the same wavelength.

I have only white walls in my home which is perfect for signal reflection but I don't experience the problem described here. Instead I have a very good signal reception from almost any position :-). Also the reflected signal is quickly dissipated and cannot bounce back and forth between walls that long.

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Hi Mathead, my issues were definitely caused by some interference/voltage on the USB shielding - I was able to measure it on a multimeter. Since adding a permanent earth to the shield my flirc has worked like a dream :)

 

I had tried the flirc with no casing/taped up casing before with no success.

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Well the easy way to test if you have the same issue as me is to hold your finger on the metal shielding of the USB, then try the remote and see if the keys have stopped sticking. You can also try touching the shielding while the keys are stuck repeating and see if they stop.

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I think that first thing to do is to check if the device is properly grounded from the power outlet. If this is a PC with a three lead plug and the outlet is grounded then whole PC is already grounded together with its USB ports. If it's the raspberry pi we are talking about then there is a good chance that the power supply is a simple PSU without the ground lead. You don't need to solder anything to anything actually. RPi have ground pins in its GPIO pin header which can be used to ground the whole setup. Just look up the GPIO pin header description on Google or directly on RPi wiki. Just note which exactly version of pi you have as there were some changes with a second version (the one with mounting holes).

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So the solution is definitely soldering?

 

I'm not so good at that :(

If you can live with something that doesn't look great, see my post above on how I fixed this.

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I don't get it, my shield is grounded. so if your computer grounded the mating shields, it should be fine....

 

Anyone have a multimeter?

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