Understanding IR codes for Samsung TV

问题

Can somebody help me to understand how could I use RAW IR data in an project using ESP8266-HTTP-IR-Blaster library ?

I've created a NodeMCU board with an IR sender and receiver according to https://github.com/mdhiggins/ESP8266-HTTP-IR-Blaster

Everything is working fine as long as I'm using the captured codes for ex.: http://NodeMCU-IP/msg?code=E0E040BF:SAMSUNG:32 This is the Code for the Power button (E0E040BF)

As I'm using it in a home automation system, it would very beneficial for me if I had a dedicated ON and OFF sequence, which I found here: http://www.remotecentral.com/cgi-bin/mboard/rc-discrete/thread.cgi?5780 , but unable to translate, modify, or send it via RAW data.

Using Node-red, tried many ways, also implemented a MQTT client to the original project, but did not accept these codes anyhow I try. Does not sends it.

Also tried as a JSON, didn't help.

[
    {
    "type":"raw",
    "data":"[0000, 006D, 0000, 0022, 00AC, 00AC, 0015, 0040, 0015, 0040, 0015, 0040, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0040, 0015, 0040, 0015, 0040, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0015, 0040, 0015, 0040, 0015, 0015, 0015, 0015, 0015, 0040, 0015, 0040, 0015, 0040, 0015, 0040, 0015, 0015, 0015, 0015, 0015, 0040, 0015, 0040, 0015, 0015, 0015, 0689]",
    "khz":38
    }
]

Any idea what could I try next?

回答1:

A good introduction to the 'Pronto format' that you show above is at Remote Central

For the specific example above, for a Samsung OFF code given at your remote central link, the full code is given as a sequence of 16-bit numbers represented in hexadecimal with spaces in between:

0000 006D 0000 0022 00AC 00AC 0015 0040 0015 0040 0015 0040 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0040 0015 0040 0015 0040 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0040 0015 0040 0015 0015 0015 0015 0015 0040 0015 0040 0015 0040 0015 0040 0015 0015 0015 0015 0015 0040 0015 0040 0015 0015 0015 0689

You can break that down as a preamble (broken out here for interest, but not needed if you already have a working Samsung code):

0x0000 - This is raw code format data
0x006D - Frequency 109 decimal = 38.028kHz (see above link for calculation)
0x0000 - No burst pairs in first sequence
0x0022 - 34 decimal - 34 burst pairs of signal follow
00AC 00AC - First burst of signal - on for 0xAC (172 decimal) cycles at 38kHz, off for the same amount
After that comes 32 pairs of data "burst pairs" (which is likely the only bit you need if you already have other codes for the same device)
0015 0689 - Final burst of signal - on for 0x15 (21 decimal) cycles, off for 0x689 (1673 decimal) cycles, guaranteeing 44ms without any IR before the next code can be transmitted

To interpret the data manually, copy it out (e.g. into a text editor) in groups of 8 numbers:

0015 0040 0015 0040 0015 0040 0015 0015 
0015 0015 0015 0015 0015 0015 0015 0015 
0015 0040 0015 0040 0015 0040 0015 0015 
0015 0015 0015 0015 0015 0015 0015 0015 
0015 0015 0015 0015 0015 0015 0015 0040 
0015 0040 0015 0015 0015 0015 0015 0040 
0015 0040 0015 0040 0015 0040 0015 0015
0015 0015 0015 0040 0015 0040 0015 0015

Then:

Ignore the columns where all the numbers are the same (even columns above, which represent the on time - 0x15 = 21 decimal cycles of IR at 38kHz )
For the remaining columns (which represent the off-time), replace the big numbers (0x40 in this case) with '1' and the small (0x15) with '0'.

For the first line

0015 0040 0015 0040 0015 0040 0015 0015

ignoring the even numbered columns leaves:

0040 0040 0040 0015

replacing those with 1's and 0's

1    1    1    0

and if you convert that into hexadecimal, it's 'E'

Next line is '0', then 'E' then '0' (already it's comforting to see it starting with the same E0E0 that starts your other Samsung code above...), and the remaining lines make it E0E019E6

Doing the same with the ON code gives you E0E09966

And as I've needed to solve the same problem just recently for the same codes, I can confirm that my Samsung TV responds to those codes as OFF and ON.

Not surprisingly, there are a variety of software tools to convert between formats, and a huge range of formats to describe the same signal (explained very well by xkcd). For example, irdb.tk will decode the above string to "Protocol NECx2, device 7, subdevice 7, OBC 152". It's up to you to know that you have to

bit-reverse the device number '07' to get 'E0'
bit-reverse the subdevice number (also '07') to get 'E0'
convert 152 to hexadecimal and reverse the bits to get '19'
calculate the last two digits as ( 0xFF - the bit-reversed OBC ), 0xFF - 0x19 = 0xE6, giving the final 8 bits 'E6'

来源：https://stackoverflow.com/questions/60718588/understanding-ir-codes-for-samsung-tv

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arduino

esp8266

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