Error message

  • Warning: count(): Parameter must be an array or an object that implements Countable in theme_table() (line 1998 of /data/sigrok.org/apache/blog/includes/theme.inc).
  • Warning: count(): Parameter must be an array or an object that implements Countable in theme_table() (line 2061 of /data/sigrok.org/apache/blog/includes/theme.inc).
  • Deprecated function: implode(): Passing glue string after array is deprecated. Swap the parameters in drupal_get_feeds() (line 394 of /data/sigrok.org/apache/blog/includes/common.inc).

New protocol decoder: ir_nec

Submitted by Uwe Hermann on Fri, 03/14/2014 - 20:05

We're happy to announce that libsigrokdecode now supports yet another protocol decoder, this time: ir_nec. The PD has been contributed by Gump Yang, thanks a lot!

This is a decoder for the so-called NEC infrared (IR) protocol, a rather widely used protocol for remote controls (for TVs, VCRs, and lots of other things).

The protocol is based on a pulse-distance encoding, i.e., a 1 bit is encoded by a pulse and a long pause after that, and a 0 is encoded by a pulse and a short pause after the pulse.

The "payload" basically consists of an 8-bit address (which is a number that is supposed to be unique for a certain vendor / device), and an 8-bit command / code which identifies which button was actually pressed.

The 8-bit address is followed by the inverted 8-bit address, the 8-bit code is also followed by its inverse. This is (or can be) used for error checking on the receiver side.

You can read up on the protocol details in various online resources.

When the proper definitions for specific remote controls are added to the PD, it can also decode the actual remote control button in a more human-readable form e.g. "Matsui TV: Mute" vs. "Address: 0x40, command: 0x10", see screenshot for an example.