espressif/rmt: replace rmtchar with arch-specific lirc adapter by PiyushPatle26 · Pull Request #18654 · apache/nuttx

PiyushPatle26 · 2026-03-30T22:11:14Z

Note: Please adhere to Contributing Guidelines.

Summary

Replace the ESP-specific rmtchar upper-half with arch-local esp_lirc adapters for Xtensa and RISC-V.

This moves the RMT upper-half out of drivers/rmt, registers LIRC
devices from the ESP board bring-up paths, and removes the old common
rmtchar driver and headers.

Also update the ESP Kconfig and build wiring to build esp_lirc when
ESP_RMT and DRIVERS_RC are enabled.

Impact

Moves ESP-specific RMT support from common drivers/rmt into arch-local esp_lirc, aligning with NuttX layering.
Replaces the legacy rmtchar interface with the standard LIRC framework and removes obsolete code.
Registers LIRC devices from board bring-up, fixing RX/TX device conflicts and improving stability.
Limited to ESP targets; out-of-tree users must migrate to /dev/lircX

Testing

Tested on: ESP32-DEVKITC (Chip v1.0)
booted with CONFIG_ESP32_IGNORE_CHIP_REVISION_CHECK=y for local validation only

flashed and booted successfully to NSH
confirmed device registration:
- /dev/lirc0
- /dev/lirc1
- /dev/leds0
confirmed the previous TX registration collision was fixed
- before fix: board_rmt_txinitialize() failed: -17
- after fix: both /dev/lirc0 and /dev/lirc1 register
confirmed the RX worker thread crash was fixed
- before fix: opening the RX side triggered a kernel panic in esp_lirc_rx_thread
- after fix: devices open successfully

Fixes discovered during hardware validation:

register TX as /dev/lirc1 so RX and TX do not collide
parse the RX worker thread argument from the correct argv slot
keep RX devices from advertising TX capability

Test logs:

Irtest seems struck so need guidance on what must be changed to validate completely

drivers/rmt/Kconfig

drivers/rmt/Make.defs

drivers/rmt/CMakeLists.txt

acassis · 2026-03-31T11:27:52Z

@PiyushPatle26 I liked the idea, however ESP32 RMT is use not only for RC, it is used as signal "generator" to control WS8212 RGB LEDs for example. Similar how people use I2S to emulate other protocols.

@fdcavalcanti @tmedicci @eren-terzioglu please take a look

acassis · 2026-03-31T11:28:59Z

@xiaoxiang781216 who from Xiaomi could help him: "Irtest seems struck so need guidance on what must be changed to validate completely" ?

acassis

@PiyushPatle26 nice work! Kudos!!!
You didn't submit a Documentation about this driver, so searching further I noticed we even don't have basic documentation about RC: https://nuttx.apache.org/docs/latest/components/drivers/character/rc.html#remote-control-devices

Could you please help us to improve it?

raiden00pl · 2026-03-31T11:47:36Z

related issue: #15431

tmedicci · 2026-03-31T13:19:26Z

@PiyushPatle26 I liked the idea, however ESP32 RMT is use not only for RC, it is used as signal "generator" to control WS8212 RGB LEDs for example. Similar how people use I2S to emulate other protocols.

@fdcavalcanti @tmedicci @eren-terzioglu please take a look

Thanks for submitting it, @PiyushPatle26 . We are testing on our internal CI. Please don't merge it yet.

As Alan pointed, @PiyushPatle26 , the RMT driver is used to drive the WS2812 (on-board LED for some of the Espressif's boards). Did you test it?

PiyushPatle26 · 2026-03-31T13:55:07Z

@xiaoxiang781216 have removed the files you asked for
@acassis Added the documentation as asked
@tmedicci not yet, my ESP32-devkitc doesn't have a WS2812 on board LED , can use a external ws2812 with jumper wires for proper testing

xiaoxiang781216 · 2026-03-31T14:39:17Z

@xiaoxiang781216 have removed the files you asked for @acassis Added the documentation as asked @tmedicci not yet, my ESP32-devkitc doesn't have a WS2812 on board LED , can use a external ws2812 with jumper wires for proper testing

need fix:

    1: .codespellrc
Warning: /home/runner/work/nuttx/nuttx/nuttx/arch/risc-v/src/common/espressif/esp_lirc.h:26:1: warning: #include outside of 'Included Files' section
Warning: /home/runner/work/nuttx/nuttx/nuttx/arch/risc-v/src/common/espressif/esp_lirc.h:28:1: warning: #include outside of 'Included Files' section
Some checks failed. For contributing guidelines, see:

PiyushPatle26 · 2026-03-31T16:09:38Z

@xiaoxiang781216, I have made the changes you asked.

linguini1

Please read the contributing guide and update the PR description to match the requirements :)

PiyushPatle26 · 2026-03-31T23:29:22Z

@linguini1 I have made all the changes according to contributing.md

eren-terzioglu · 2026-04-01T12:29:04Z

Please check CI errors

acassis · 2026-04-01T12:32:43Z

@PiyushPatle26 as @tmedicci you need to test it with existing usage case: i.e. to control WS8212 RGB LED matrix. Otherwise you will broke an existing feature

Hi, Tested internal RGB led using rmt defconfig with ws2812 example. C6 and S3 is working fine

So the snake and shift game still working? That is the most important thing to save! :-D

eren-terzioglu · 2026-04-01T12:35:33Z

@PiyushPatle26 as @tmedicci you need to test it with existing usage case: i.e. to control WS8212 RGB LED matrix. Otherwise you will broke an existing feature

Hi, Tested internal RGB led using rmt defconfig with ws2812 example. C6 and S3 is working fine

So the snake and shift game still working? That is the most important thing to save! :-D

I have to find the demo board but even if it doesn't; it would be somehow different, no worries. :)

Replace the ESP-specific rmtchar upper-half with arch-local esp_lirc adapters for Xtensa and RISC-V. This moves the RMT upper-half out of drivers/rmt, registers LIRC devices from the ESP board bring-up paths, and removes the old common rmtchar driver and headers. Also update the ESP Kconfig and build wiring to build esp_lirc when ESP_RMT and DRIVERS_RC are enabled. Fixes discovered during hardware validation: - register TX as /dev/lirc1 so RX and TX do not collide - parse the RX worker thread argument from the correct argv slot - keep RX devices from advertising TX capability Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>

PiyushPatle26 · 2026-04-01T20:17:24Z

Please check CI errors

Hey @eren-terzioglu, i think CI errors should be fixed now
@acassis I was not able to test as I just have a ESP32-devkitC which doesn't have WS8212, But i think @eren-terzioglu have already tested, right?

linguini1 · 2026-04-01T21:32:52Z

Ideally you should have a way to test your changes in some capacity. Also, the CI is failing because of config files which aren't normalized. You can use tools/refresh.sh to normalize them :)

PiyushPatle26 · 2026-04-01T22:08:30Z

Ideally you should have a way to test your changes in some capacity. Also, the CI is failing because of config files which aren't normalized. You can use tools/refresh.sh to normalize them :)

Sorry for not being able to test properly, Thanks for helping for CI, now i have normalized the configs

eren-terzioglu · 2026-04-02T07:27:40Z

Please check CI errors

Hey @eren-terzioglu, i think CI errors should be fixed now @acassis I was not able to test as I just have a ESP32-devkitC which doesn't have WS8212, But i think @eren-terzioglu have already tested, right?

I did not test for esp32, only made for esp32c6 and esp32s3 let me test and report back

Update: Seems it is fine too, fyi

simbit18 · 2026-04-02T12:19:31Z

Hi @PiyushPatle26, please fix

====================================================================================
Configuration/Tool: esp32-devkitc/match4
2026-04-01 23:08:58
------------------------------------------------------------------------------------
  Cleaning...
  Configuring...
  Building NuttX...
  [1/1] Normalize esp32-devkitc/match4
29d28
< CONFIG_ESP_RMT=y
31,33d29
< CONFIG_EXAMPLES_RMTCHAR=y
< CONFIG_EXAMPLES_RMTCHAR_RX=y
< CONFIG_EXAMPLES_RMTCHAR_TX=y
53,55d48
< CONFIG_RMT=y
< CONFIG_RMTCHAR=y
< CONFIG_RMT_DEFAULT_RX_BUFFER_SIZE=256
Saving the new configuration file
HEAD detached at pull/18654/merge
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   boards/xtensa/esp32/esp32-devkitc/configs/match4/defconfig

no changes added to commit (use "git add" and/or "git commit -a")
====================================================================================

Add documentation for the RC/LIRC character driver subsystem covering device registration, the LIRC interface, and usage from user space. Remove placeholder empty files under drivers/rmt that were left over from the rmtchar era and are no longer referenced. Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>

PiyushPatle26 · 2026-04-02T15:32:44Z

tools/refresh.sh

Hi @PiyushPatle26, please fix

====================================================================================
Configuration/Tool: esp32-devkitc/match4
2026-04-01 23:08:58
------------------------------------------------------------------------------------
  Cleaning...
  Configuring...
  Building NuttX...
  [1/1] Normalize esp32-devkitc/match4
29d28
< CONFIG_ESP_RMT=y
31,33d29
< CONFIG_EXAMPLES_RMTCHAR=y
< CONFIG_EXAMPLES_RMTCHAR_RX=y
< CONFIG_EXAMPLES_RMTCHAR_TX=y
53,55d48
< CONFIG_RMT=y
< CONFIG_RMTCHAR=y
< CONFIG_RMT_DEFAULT_RX_BUFFER_SIZE=256
Saving the new configuration file
HEAD detached at pull/18654/merge
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   boards/xtensa/esp32/esp32-devkitc/configs/match4/defconfig

no changes added to commit (use "git add" and/or "git commit -a")
====================================================================================

Done

The common ESP board RMT bring-up files are built whenever ESP_RMT is enabled, but the esp_lirc declarations are only visible when DRIVERS_RC is enabled. Guard the esp_lirc header include and esp_lirc_rx_initialize() / esp_lirc_tx_initialize() calls with CONFIG_DRIVERS_RC so non-RC ESP configs continue to build while keeping the LIRC registration path for the rmt configs. Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>

esp_ws2812.h exposes esp_ws2812_setup() with a struct rmt_dev_s * argument but did not include esp_rmt.h directly. After guarding the LIRC board registration path with CONFIG_DRIVERS_RC, non-RC ESP configs no longer pulled in the RMT type indirectly and CI started failing with an incomplete struct rmt_dev_s declaration. Include esp_rmt.h in the Xtensa and RISC-V ws2812 headers. Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>

acassis · 2026-04-03T18:41:26Z

@linguini1 PTAL, he already fixed the Summary

PR fixed!

Add: - replace rmtchar with arch-specific lirc adapter apache#18654 Signed-off-by: simbit18 <simbit18@gmail.com>

PiyushPatle26 requested review from acassis, fdcavalcanti, jerpelea, pkarashchenko, tmedicci and xiaoxiang781216 as code owners March 30, 2026 22:11

xiaoxiang781216 reviewed Mar 31, 2026

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acassis reviewed Mar 31, 2026

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PiyushPatle26 requested a review from raiden00pl as a code owner March 31, 2026 13:23

xiaoxiang781216 previously approved these changes Mar 31, 2026

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PiyushPatle26 dismissed xiaoxiang781216’s stale review via a214d60 March 31, 2026 13:46

PiyushPatle26 force-pushed the espressif-rmt-lirc-refactor branch from 03469b0 to a214d60 Compare March 31, 2026 13:46

PiyushPatle26 force-pushed the espressif-rmt-lirc-refactor branch from a214d60 to e94f877 Compare March 31, 2026 16:08

linguini1 previously requested changes Mar 31, 2026

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PiyushPatle26 force-pushed the espressif-rmt-lirc-refactor branch 2 times, most recently from 07a76b6 to f9787c9 Compare March 31, 2026 23:28

PiyushPatle26 force-pushed the espressif-rmt-lirc-refactor branch from 411e3b0 to 3acd6c5 Compare April 1, 2026 20:15

PiyushPatle26 dismissed jerpelea’s stale review via b3972b6 April 1, 2026 22:06

PiyushPatle26 force-pushed the espressif-rmt-lirc-refactor branch from 3acd6c5 to b3972b6 Compare April 1, 2026 22:06

acassis previously approved these changes Apr 2, 2026

View reviewed changes

PiyushPatle26 dismissed acassis’s stale review via c5abfb4 April 2, 2026 15:30

PiyushPatle26 force-pushed the espressif-rmt-lirc-refactor branch from b3972b6 to c5abfb4 Compare April 2, 2026 15:30

PiyushPatle26 requested review from acassis, linguini1 and xiaoxiang781216 April 2, 2026 17:02

PiyushPatle26 added 2 commits April 3, 2026 00:45

xiaoxiang781216 approved these changes Apr 3, 2026

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PiyushPatle26 requested a review from jerpelea April 3, 2026 16:26

acassis approved these changes Apr 3, 2026

View reviewed changes

acassis merged commit 5796849 into apache:master Apr 4, 2026
42 checks passed

PiyushPatle26 deleted the espressif-rmt-lirc-refactor branch April 4, 2026 15:32

simbit18 added a commit to simbit18/nuttx that referenced this pull request Apr 6, 2026

arch/risc-v/src/common/espressif: Aligned Cmake with Make

c85bf7e

Add: - replace rmtchar with arch-specific lirc adapter apache#18654 Signed-off-by: simbit18 <simbit18@gmail.com>

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