GPIO IR remote stops working when Ethernet cable unplugged

I am running stable release on RPi2. I have been using a GPIO receiver (hardwired into GPIO pins) and an Xbox IR remote for several weeks now. Today I noticed an odd phenomenon: if I disconnect my Ethernet cable, the Pi immediately stops responding to remote inputs.

I cannot understand why the Ethernet cable and IR GPIO would be related. But it is quite repeatable. As soon as I plug the Ethernet cable back in, remote works perfectly again. Unplug Ethernet cable, and suddenly no response from the IR remote.

Any ideas?

I found a couple of references that appear to be directly related:

Reference 1 says that unplugging Ethernet floods LIRC with phantom keystrokes. Ultimately solved by replacing IR sensor with new TSOP4838 (@DBMandrake suggested this to me some time ago, so I guess I will start here)

Reference 2 points to electrical noise on the 3.3V line, which affects performance of the IR receiver. The noise is suppressed when the Ethernet cable is plugged in. Solution here was to run off the 5 V rail, using a resistor to drop voltage back to 3.3V and a capacitor to clean the voltage.

I’d still be very interested to hear if anyone here has had similar issues, and what their solution was.

You might also wonder why bother - just keep running off Ethernet, and be done with it. The reason is that I am looking to change from Ethernet to WiFi. I will soon be moving to a new house, and the new layout will make it harder to run Ethernet to my osmc setup.

You don’t say what model of IR receiver you are using and whether you are powering it from 3.3v or 5v ?

What kind of power adaptor are you using ? The “electrical noise” is most likely coming from the power adaptor itself. The noise level generated by the switching regulator in the power adaptor will vary with the load.

No problems like you describe with my GPIO IR receiver…

I am using a TRM1038 and 3.3V. The Pi is powered using this 2A switching power supply.

In the other thread I referenced, I think you mentioned you are using a TSOP38238. Is that still the case? If so, I will start by switching over to that sensor and see if it resolves the problem. “Reference 1” in my original post also mentioned fixing this problem by switching to a new sensor (TSOP4838, in that case). So I am hopeful it is simply a sensor issue. Good to know you do not have this issue.

I am curious about your statement that the noise would come from the power adapter. Wouldn’t the Raspberry Pi have some kind of conditioning circuitry to clean it up? As far as I know, the supply is providing the 5V (reported to be clean in “Reference 2”), and the 3.3V comes from onboard circuitry (reported to have noise). So doesn’t this suggest an issue on the Pi itself?

Simple as that! Replaced the IR receiver with a TSOP38238 and the issue is resolved.

I notice that this chip explicitly highlights its electrical noise rejection benefits, so I think this is what did the trick:

I want to know that whether you are powering it from 3.3v or 5v ? Also which adaptor are you using ?
Actually the noise mostly comes from the power adaptor itself.
The noise level generated by the switching regulator in the power adaptor will vary with the load.

pcb quote

The info you asked for is a couple of posts up (running off 3.3V, and a link provided to the 2A adapter I use).