lirc_rawcode2wav

This script convert to wav file from the rawcode of mode2 command(lirc). It made for CHIP. but it can work any env. maybe.

settings

item	descriptions
RATE	output file sampling rate[Hz]
BIT	output file bit depth
SOX_CMD	sox command path

usage - make wav file

execute with two arg that is input_file_name and output_file_name

[yourmachine]% ./rawcode2wav.sh ./inputfile.txt ./outputfile.wav

usage - IR transmit

play a wav file.

[yourmachine]% aplay ./outputfile.wav
Playing WAVE 'outputfile.wav' : Signed 24 bit Little Endian in 3bytes, Rate 192000 Hz, Stereo

software requirements

• sox
• bash
• egrep / fgrep / sed
• bc

Note: this script generate a very long command line. it is restricted by ARG_MAX.

[yourmachine]% getconf ARG_MAX
2097152

hardware requirement

• C.H.I.P. or any env?
• IR-LEDs (2 LEDs required)

hardware connection

   CHIP
+--------+
|        |
|     HP L----------------------------------+
|        |                                  |
|     HP R-----||------*---[ IR LED |>| ]---*
|        |      C1     |                    |
+--------+             +---[ |<| IR LED ]---+
 
+ : corner/cross-over
* : connect
HP L/R : audio output Left/Right
C1 : 1uF or less

hardware connection for mode2 (optional)

        CHIP          IR receiver
     +--------+       +---------+
     |        |       |         |
     |   VCC-5V-------VCC  OUTPUT---+
     |        |       |         |   |
     |      GND---*---GROUND    |   |
+----MIC IN   |   |   |         |   |
|    +--------+   |   +---------+   |
|                 |                [R1]
|                 |                 |
|                 |                 *----+
|                 |                 |    |
|                 |                [R2]  |
|                 |                 |    |
|                 +-----------------+    |
|                                        |
+----------------------------------[C1]--+
 
+ : corner/cross-over
* : connect
R1 : 100k Ohm
R2 : 560 Ohm
C1 : 1 uF or less

R1 and R2 is needed to avoid input saturation/clipping. it's very important for stabilise a mode2.

reffer

https://bbs.nextthing.co/t/installing-lirc-on-c-h-i-p/2449/5 https://web.archive.org/web/20180602133626/https://bbs.nextthing.co/t/installing-lirc-on-c-h-i-p/2449

usage example

# install tools
[yourmachine]% sudo apt-get install lirc bc sox

# get RAW_CODES
[yourmachine]% sudo mode2 -H audio_alsa -d default | tee inputfile.txt
space 765
pulse 127
space 214
pulse 80
space 1208273
pulse 2624
space 2658
<snip>
pulse 852
space 1895
pulse 831
space 809
pulse 855
^C                <--- Ctrl-C to exit

# convert to wav
[yourmachine]% ./rawcode2wav.sh ./inputfile.txt outputfile.wav
/usr/bin/sox WARN sox: `outputfile.wav' output clipped 46 samples; decrease volume?

# IR transmit
[yourmachine]% aplay outputfile.wav
Playing WAVE 'outputfile.wav' : Signed 24 bit Little Endian in 3bytes, Rate 192000 Hz, Stereo

sox said anything, it's ok. It's using a sine wave with max amplitude.

recommendation

• Edit a RAW_CODES to only a sequence of IR code, before convert. it's appear between leader-code and long space.
• Edit a RAW_CODES to acutual format of NEC-format, AEHA-format or SONY-format.