Remote not controlling PVR properly (not batteries)

[everthewatcher]

Does the OP have any unaccounted for remote control handsets?

Good point. Ten years or so back when I was working with IR remote control I made up a sniffer consisting of an 38kHz IR receiver coupled to a piezo sounder for spotting and tracking down rogue sources.

[Edit] Comes in very useful for checking all the buttons on a remote work OK.

 

[everthewatcher]

...I made up a sniffer consisting of an 38kHz IR receiver...

Here's the cct if anyone's interested. Apologies for the crop at the right.

Built on Vero and powered by a PP3 it fits into a pocketable 72 x 60 x 24mm box. The LED is a very high efficiency red one.

 

[af123]

Are you sure about that? The NEC format as used by the Humax transmits the address and data code once on a button press followed by the short 'repeat' code if it's held down. The multiple log entries for one button press seem to indicate the log software adding one complete code to the log for every repeat code received.

No I'm not sure. There's obviously some translation going on somewhere, most likely in the Broadcom nexus layer. The software sees each IR code as keydown + keycode followed by keyup + keycode. They don't always come in pairs, there can be several keydown events followed by a single keyup.

 

[everthewatcher]

Here's the cct...

As this seems to be liked, here are some notes along with a picture.

The project was a quick build-it-with-what's to-hand one, hence the notes on salvaged components.

IR receiver used clearly has an internal pull-up on the output. Some have an open collector output and will need a pull-up resistor (say 47k) to +V.

The piezo element used had the vital property of being very thin.

The big white circle is a felt pad to stop the battery rattling.

 

[af123]

[Edit] Comes in very useful for checking all the buttons on a remote work OK.

Nowadays smartphone (or any other digital) cameras do the job but this presumably pre-dates them.

 

[everthewatcher]

Nowadays smartphone (or any other digital) cameras do the job but this presumably pre-dates them.

Way before smartphones (ignore the date on the cct) though but not digital cameras, both of which may have near-IR filters on them.

It's a receiver, not a camera, with an audio output. So you can hear is it's say NEC, Sony or Philips/RC5 and also get a good idea of the range of a given transmitter.

 

[everthewatcher]

No I'm not sure. There's obviously some translation going on somewhere, most likely in the Broadcom nexus layer. The software sees each IR code as keydown + keycode followed by keyup + keycode. They don't always come in pairs, there can be several keydown events followed by a single keyup.

That suggests it's marking keyup as the end of the short 'repeat' code transmission. The succession of keydowns before a keyup may be the result of pressing several keys in quick succession coupled with latency.

FWIW I've just gone through the Humax RM-F04 remote and all keys do code+repeat except the PVR, TV, DVD & AUDIO ones - they just transmit the code once.

 

[Black Hole]

Nowadays smartphone (or any other digital) cameras do the job but this presumably pre-dates them.

With a camera you have to specifically look for a source (and as noted above the latest batch of cameras won't do it anyway). ETW's unit looks great as a sniffer, as he said.