RC5 / RC6 toggle-bit, repeat and debouncing behaviour

[Jason-R1]

I'm trying to understand how RC5/RC6 protocols represent button press, repeat and held-key behaviour, particularly when using Pronto Hex and IRPlus.

Although my immediate application is a Microsoft eHome receiver, I suspect the underlying question is really about RC5/RC6 protocol behaviour, so I'm hoping someone with knowledge of RC5/RC6, Pronto Hex or IRPlus may be able to help.

Background

I've been comparing RC6 commands from three different sources:

• the built-in IRPlus Microsoft MediaCentre library
• IrScrutinizer generated Pronto Hex
• learned IR captures

One thing I noticed is that many of the original IRPlus library entries consist of two Pronto Hex sequences separated by |.

The two sequences are similar, but not identical.

This raised a number of questions about how RC5/RC6 repeat behaviour is intended to work.

What I've observed

Using IrScrutinizer's Windows Keyboard JP1 definitions I've generated valid RC6 keyboard commands.

Discrete commands work correctly. For example:

• Alt+F4
• Alt+Tab
• Ctrl+Alt+Del
• Windows-key combinations

However, commands that rely on a genuine press-and-hold do not behave like the original hardware.

For example:

• Holding Esc on the original keyboard exits full-screen in many applications.
• Repeatedly transmitting the Esc IR command behaves only as repeated presses.
• Holding Alt while repeatedly pressing Tab cycles through all open windows.
• Repeating the Alt+Tab IR command simply toggles between the two most recently used windows.

I've experimented with:

• different repeat counts
• repeat frequencies
• hybrid Pronto sequences
• repeated transmissions

but haven't yet reproduced true held-key behaviour.

Questions

For RC5 / RC6 protocols in general:

• How are press, repeat and release normally represented?
• Is there any concept of a "key held" state within the protocol?
• Is the toggle bit involved in generating held-key behaviour, or is it intended only to distinguish successive button presses?
• When using Pronto Hex, should a held key normally be represented by:
  • repeated identical frames,
  • alternating toggle-bit frames,
  • different repeat frames,
  • or simply transmitter timing?

IRPlus question

Does anyone know how IRPlus implements repeated transmission?

Specifically:

• What does the | separator actually mean internally?
• Does IRPlus insert any special timing between the two Pronto sequences?
• During a button hold, does IRPlus repeatedly transmit:
  • the complete sequence,
  • only the second sequence,
  • or something else?

Debouncing / Toggle

I've also read that the RC5/RC6 toggle mechanism is used not only to distinguish successive button presses, but also as part of preventing multiple detections caused by:

• mechanical switch bounce,
• repeated IR transmissions,
• or reflections of the IR signal around the room.

If that's correct, could this also explain why simply repeating the same Pronto frame does not produce the same behaviour as holding a button on the original remote or keyboard?

Looking for protocol-level understanding

I'm really interested in understanding the protocol itself rather than just solving one application.

Any information on:

• RC5 / RC6 repeat behaviour
• toggle-bit implementation
• held-key semantics
• Pronto Hex repeat structure
• IRPlus transmission behaviour

or links to protocol documentation or previous reverse-engineering work would be greatly appreciated.

Thanks!

[serp369molot]

___Не интересовался про про RC6, а в RC5 используется ToggleBit - то есть чётные и нечётные посылки при нескольких нажатиях одной кнопки передаются с разными заголовками. Если кнопка удерживается - отправляется серия посылок с одинаковыми заголовками. Так устройство понимает, это удержание или серия нажатий - в том числе и механический дребезг. На само определение команд влиять не должно. Если команды не исполняются устройством - причина в другом. Хотя это может быть и неисправность устройства. Есть возможность проверить работу команд с другим устройством, использующим RC6? ТВ, ДВД и прочее.