Woud different type of IR transmitter affect the sent raw data ?

[twinsenfan]

I am trying to decode an IR remote for a ceiling light. Managed to decode with the IRrecvDumpV3, here is what I got

Code : 0xFE6D6BB6 (38 Bits)
uint16_t rawData[75] = {3398, 1716, 398, 1300, 398, 1300, 398, 428, 396, 428, 416, 1280, 398, 428, 418, 404, 396, 430, 396, 1300, 398, 1300, 398, 1300, 398, 428, 396, 1300, 420, 404, 398, 426, 396, 428, 418, 406, 398, 426, 396, 1300, 400, 428, 396, 426, 418, 404, 396, 428, 396, 426, 396, 426, 420, 1278, 418, 404, 398, 428, 396, 1302, 398, 1300, 398, 1300, 398, 1302, 398, 1300, 398, 426, 418, 1280, 420, 1280, 444}; // UNKNOWN FE6D6BB6

I was able to send it with sendRaw(rawDataOff,75, 38) using an IR transmitter like below and the light responded to the code sent.
https://europe1.discourse-cdn.com/arduino/original/4X/1/3/3/1336d7c9b35c7eee07957c9b8064b9f647b00dec.jpeg

However, the same code does not work if I use an IR Led connected to the same pin together with a 200ohm resister. I dumped the IR signal and it was completely different. I've also tried other IR Led. Here is the datasheet for one of them
https://www.marutsu.co.jp/contents/shop/marutsu/datasheet/503HIRT2V-1CD.pdf

Any suggestions about how to debug the issue ? Thank you

[NiKiZe]

Follow the troubleshooting guide https://github.com/crankyoldgit/IRremoteESP8266/wiki/Troubleshooting-Guide#basic

TL;DR sounds like you have only connected a resistor, and not the required transistor?

[twinsenfan]

I am pretty new to IR, i do have other IR led with different wave length I can test. Does that mean the library only works with 940nm IR LED?

[crankyoldgit]

The library will work with any LED etc. The problem is at a hardware level. The IR receivers in most consumer devices are expecting IR light with a wavelength of 940nm. If you're not providing that, the hardware is likely going to have a very bad time of it.

[twinsenfan]

Ok understood. Right now I am using the same receiver to dump IR remote code and verify the rawdata sent from my transmitter. Is it correct to assume the same code should send the same rawdata through 880/940nm IR LED. On the receiver side I should get the same data captured.

[crankyoldgit]

Is it correct to assume the same code should send the same rawdata through 880/940nm IR LED.

Yes. One will have a carrier wavelength of 880nm, the other will have a carrier wavelength of 940nm.
Imagine someone sending morse code, but with either a blue light, or a red light. The message is still the same. The encoded message is still the same, however if you can't see blue light well, then you're stuffed.

On the receiver side I should get the same data captured.

No.
Using the above analogy, a typical IR demodulator in consumer devices is expecting "Red" light. It is tuned to see "Red" light, it may not see "Blue" light at all, or might only detect "Blue" light as "Red" about 20% of the time etc.

In short, unless you're using a "red" light producing flashlight to send a signal to someone who can only "see" red, then things are going to be terrible.
Using a "green" or "blue" light producing flashlight is going to have unpredictable behavior, or not be seen at all.

Just to make sure it's clear (on a different point per FAQ I indicated earlier), you are almost NEVER going to get/capture the exact same "raw" timings for the same message being sent. You're converting from digital to analogue and back to digital again with significant distortion/fidelity loss at every point along the way.

[twinsenfan]

Thank you for the detailed explanation, I guess I need to find the IR LED with the same wavelength used in my "working" transmitter and move on from there.