Hello, First of all, let's see if I got this right. An infrared remote control emits IR pulses to send a bitstream. This is the "raw" data. The bit sequence depends on the button being pressed (or released), and the protocol being used, right? An infrared receiver "captures" this bitstream, which is then translated to a "scancode" using the appropriate (protocol) decoder, IIUC. How does one know which decoder to use, out of the dozen protocols available? Are there ambiguities such that a bitstream may be valid under two different protocols? Hmmm, I'm missing a step for going from 00000000 a9 07 00 00 2e 72 0e 00 04 00 04 00 41 cb 04 00 |.....r......A...| 00000010 a9 07 00 00 2e 72 0e 00 00 00 00 00 00 00 00 00 |.....r..........| to 2589.901611: event type EV_MSC(0x04): scancode = 0x4cb41 2589.901611: event type EV_SYN(0x00). (not the same IR frame, BTW) Once we have a scancode, there is another translation pass, to the higher-level concept of an actual key, such as "1", which all applications can agree on. On the board I'm working on (Sigma SMP8758) there are two distinct infrared hardware blocks. A) the first block supports 3 protocols in HW (NEC, RC-5, RC-6A) Documentation states: "supports NEC format, RC5 format, RC5 extended format, RC6A format, interrupt driven, contains error detection" B) the second block doesn't understand protocols and only captures raw bitstreams AFAIU. Documentation states: "Support for up to 2 IR sources Contains debounce and noise filter Contains Timestamp mode or Delta mode Scancodes are timestamped Freely user programmable May support any IR protocol or format May support any scan code length Timebase either variable system clock or fixed 27MHz clock Interrupt driven GPIO pin user selectable" Tangent: it seems complicated to use two IR sources concurrently... Wouldn't both receivers capture both sources? Back on topic: it seems to me that Linux supports many protocol decoders, including the 3 supported by block A. I am also assuming that IR signals are pretty low bandwidth? Thus, it would appear to make sense to only use block B, to have the widest support. What do you think? Regards.
