ESP32-S3 RMT RX truncating IR signals - need help

lthiagovs
Posts: 2
Joined: Mon Jul 28, 2025 11:26 pm

ESP32-S3 RMT RX truncating IR signals - need help

Postby lthiagovs » Mon Jul 28, 2025 11:29 pm

I'm using ESP32-S3 with an IR receiver and the new RMT RX driver to capture RC6 infrared signals. The issue is that my transmissions are being truncated - I should get 22-24 symbols for complete RC6 frames but I'm only receiving 19-20 symbols before it cuts off. I've tried increasing buffer sizes, timeouts, and various configurations but the truncation always happens at the same point. Has anyone experienced similar RMT RX truncation issues with IR protocols?

Code: Select all

Symbol  0: L0=0 D0= 2604 | L1=1 D1=  965
Symbol  1: L0=0 D0=  386 | L1=1 D1=  957
Symbol  2: L0=0 D0=  386 | L1=1 D1=  512
Symbol  3: L0=0 D0=  393 | L1=1 D1=  510
Symbol  4: L0=0 D0=  420 | L1=1 D1=  931
Symbol  5: L0=0 D0=  863 | L1=1 D1=  478
Symbol  6: L0=0 D0=  393 | L1=1 D1=  512
Symbol  7: L0=0 D0=  393 | L1=1 D1=  518
Symbol  8: L0=0 D0=  387 | L1=1 D1=  512
Symbol  9: L0=0 D0=  391 | L1=1 D1=  520
Symbol 10: L0=0 D0=  400 | L1=1 D1=  490
Symbol 11: L0=0 D0=  418 | L1=1 D1=  474
Symbol 12: L0=0 D0=  891 | L1=1 D1=  931
Symbol 13: L0=0 D0=  413 | L1=1 D1=  490
Symbol 14: L0=0 D0=  383 | L1=1 D1=  513
Symbol 15: L0=0 D0=  851 | L1=1 D1=  962
Symbol 16: L0=0 D0=  412 | L1=1 D1=  487
Symbol 17: L0=0 D0=  426 | L1=1 D1=  477
Symbol 18: L0=0 D0=  418 | L1=1 D1=  495
Symbol 19: L0=0 D0=  394 | L1=1 D1=    0 ← END OF TRANSMISSION
Total duration: 23356 μs (23.36 ms)
Attachments
main.c
(7.5 KiB) Downloaded 17 times

Sprite
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Re: ESP32-S3 RMT RX truncating IR signals - need help

Postby Sprite » Tue Jul 29, 2025 2:38 am

I can't immediately find any fault with the code. Do you have a LA or scope trace of the signal you're receiving?

lthiagovs
Posts: 2
Joined: Mon Jul 28, 2025 11:26 pm

Re: ESP32-S3 RMT RX truncating IR signals - need help

Postby lthiagovs » Tue Jul 29, 2025 12:43 pm

I can't immediately find any fault with the code. Do you have a LA or scope trace of the signal you're receiving?
I don't have a logic analyzer available right now, but I can provide more context. I'm transmitting RC6 code 0x2401 using an Arduino with IRremote library. The transmitted signal should be a standard RC6 frame with ~22-24 symbols, but my ESP32-S3 RMT RX consistently captures only 19-20 symbols before truncating. The timing seems correct (~23ms total duration) but the frame is incomplete. Could this be related to RMT idle detection or end-of-frame detection triggering too early?

Let me also share a photo of my IR receiver module
Attachments
receiver.png
receiver.png (407.1 KiB) Viewed 100 times

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