RFC: Add RMT RX module. by elvis-epx · Pull Request #18454 · micropython/micropython

elvis-epx · 2025-11-21T02:47:24Z

Summary

This is a proposal to add RX support to esp32 RMT, that currently supports TX only.

Testing

Tested on ESP32, ESP32-S3, ESP32-C3 and ESP32-C6 boards.

Trade-offs and Alternatives

A different class esp32.RMTRX was introduced. I feel it does not have much in common with esp32.RMT, and using TX and RX at the same time over the same pin is not usual in RMT. But someone may disagree.

projectgus

Thanks for submitting this PR, @elvis-epx. I think this will be a really useful feature to have in MicroPython.

I've left some comments, mostly minor style and nitpicky things. The main high-level question I have is about the software filtering features.

The other thing that would be great to have here would a test, in tests/ports/esp32. It would be new as we also don't have a test for RMT TX ( 😢 ) but you could use the same loopback wiring pattern from tests/target_wiring/esp32.py to connect two GPIOs and then measure output from one via RMTRX. Would you be up for implementing something like this?

elvis-epx · 2026-01-21T13:33:20Z

Thanks for submitting this PR, @elvis-epx. I think this will be a really useful feature to have in MicroPython.

I've left some comments, mostly minor style and nitpicky things. The main high-level question I have is about the software filtering features.

The other thing that would be great to have here would a test, in tests/ports/esp32. It would be new as we also don't have a test for RMT TX ( 😢 ) but you could use the same loopback wiring pattern from tests/target_wiring/esp32.py to connect two GPIOs and then measure output from one via RMTRX. Would you be up for implementing something like this?

Sounds great, will take a while until I find time to write this test, but seems worthwhile.

github-actions · 2026-01-21T14:12:32Z

Code size report:

Reference:  zephyr: Add support for RISC-V RV32IMC native code emitter. [9721955]
Comparison: esp32: Add RMT simple test. [merge of 2a4ec5c]
  mpy-cross:    +0 +0.000% 
   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:    +0 +0.000% PYBV10
      esp32: +5932 +0.340% ESP32_GENERIC[incl +1440(data)]
     mimxrt:    +0 +0.000% TEENSY40
        rp2:    +0 +0.000% RPI_PICO_W
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS
  qemu rv32:    +0 +0.000% VIRT_RV32

Signed-off-by: Elvis Pfutzenreuter <[email protected]>

Small fixes and style changes in RMT RX documentation. Co-authored-by: Angus Gratton <[email protected]> Signed-off-by: Elvis Pfützenreuter <[email protected]>

Align the code style to esp32_rmt.c. Signed-off-by: Elvis Pfutzenreuter <[email protected]>

Add comment to clarify where the 15-bit value comes from. Signed-off-by: Elvis Pfutzenreuter <[email protected]>

codecov · 2026-01-26T19:39:24Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.42%. Comparing base (25b400f) to head (2a4ec5c).
⚠️ Report is 77 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #18454      +/-   ##
==========================================
+ Coverage   98.38%   98.42%   +0.04%     
==========================================
  Files         171      174       +3     
  Lines       22299    22333      +34     
==========================================
+ Hits        21938    21982      +44     
+ Misses        361      351      -10

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elvis-epx · 2026-01-26T19:41:10Z

Thanks for submitting this PR, @elvis-epx. I think this will be a really useful feature to have in MicroPython.
I've left some comments, mostly minor style and nitpicky things. The main high-level question I have is about the software filtering features.
The other thing that would be great to have here would a test, in tests/ports/esp32. It would be new as we also don't have a test for RMT TX ( 😢 ) but you could use the same loopback wiring pattern from tests/target_wiring/esp32.py to connect two GPIOs and then measure output from one via RMTRX. Would you be up for implementing something like this?

Sounds great, will take a while until I find time to write this test, but seems worthwhile.

@projectgus added a simple test, see if this is going the direction you want

projectgus

Hi @elvis-epx,

I have one minor suggestion but the new test looks great, thank you! 😁

The only other request I have is to please name the new test esp32_rmt.py instead of check_rmt.py, that's the (rough) convention we use for the other tests.

Add simple end-to-end test for RMT RX, and TX. Signed-off-by: Elvis Pfutzenreuter <[email protected]>

Backports micropython/micropython#18454 from MP 1.29 (or later)

commit 398a2ce Author: robotmad <[email protected]> Date: Tue Sep 15 21:25:59 2026 +0100 use TILDAGON_XXX_I2C_PORT definitions in place of magic numbers for I2C mux ports commit 83e1411 Author: robotmad <[email protected]> Date: Tue Sep 15 21:25:32 2026 +0100 GPIO pins via AW9523B: cache output state, direction and mode in RAM. Use tildagon-i2c-manager one-shot C callback job for the last write of any action so that micropython can return and leave that to take place in parallel. FreeRTOS Semaphore used to mange serialisation of I2C access for maximum performance. Move toggle to C layer to take advantage of caching. Update fakes for Pin and ePin. commit ffc479b Author: robotmad <[email protected]> Date: Tue Sep 15 21:23:27 2026 +0100 Frontboard 2026 compass - use tildagon-i2c-manager job for polling. The job only does data transfer - so conversion from raw bytes to meaningful values moved to the read function. commit 78da35e Author: robotmad <[email protected]> Date: Tue Sep 15 21:22:28 2026 +0100 IMU class:: use of tildagon-i2c-manager jobs for I2C polling. get and set_period() methods. Default to sensor I2C polling being Off - automatically activated on first read at 'legacy' rates 40mS for gyro/accelerometer, 1000mS for temperature and steps (now controlled separately from accel/gyro). Uses refactored BMI270 driver. Use of const to reduce RAM use. New tildagon_imu_state_t structure for RAM so that lsm6ds3 and bmi270 don't have duplicate static allocations internally. lsm6ds3 control register set to filter sensor data in sync wtih the intended I2C read poll rate. commit a78d22c Author: robotmad <[email protected]> Date: Tue Sep 15 21:21:32 2026 +0100 support 16 bit addressing of i2c device registers (e.g. SCD4X) commit 5ee12dc Author: robotmad <[email protected]> Date: Tue Sep 15 21:14:29 2026 +0100 tildagon_i2c_manager: new task in place of imu task, supports i2c operations running in parallel wtih micropython for imu, but also any other i2c transaction can now take advantage of this parallelism via C callbacks for C/micropython 'jobs'. micropython API provided for 'jobs' comprising up to 5 steps. READ/WRITE/READ16/WRITE16/CHECK step types. One-Shot (run_once) or Periodic execution with status monitoring and optional 'Pin.irq' style callback upon completion. Support for I2C devices with 8 bit and 16 bit register addressing. 10 slots for I2C callbacks/jobs. Replace extern ad-hoc declarations. commit 9c3948f Author: robotmad <[email protected]> Date: Tue Sep 15 21:01:48 2026 +0100 IMU - refactored minimal bmi270 driver in place of flow3r one, with support for setting read/update period and hence internal filters to match I2C polling period. commit f10ecb8 Author: Sam Machin <[email protected]> Date: Mon Sep 14 22:51:16 2026 +0100 Feat/utc settings (emfcamp#440) * add utc offset to settings * add utc offset to settings * store seconds use offset as label * fix formating commit 1fe0fad Author: Sam Machin <[email protected]> Date: Mon Sep 14 22:21:36 2026 +0100 keyboard enter done in TextDialog (emfcamp#443) Allows the enter key to trigger Done in a TextDialog commit f2f6a3d Author: Matthew Wilkes <[email protected]> Date: Mon Sep 14 22:19:22 2026 +0100 Add RMT RX peripheral (emfcamp#425) Backports micropython/micropython#18454 from MP 1.29 (or later) commit 9b833f0 Author: Sam Machin <[email protected]> Date: Mon Sep 14 21:28:10 2026 +0100 add ntpsync service (emfcamp#442) commit ee80b27 Author: Christopher Barnes <[email protected]> Date: Mon Sep 14 20:19:09 2026 +0100 Change FreeRTOS tick rate to 1mS (emfcamp#456)

commit 71f5e11 Author: robotmad <[email protected]> Date: Fri Sep 18 00:39:04 2026 +0100 update callaback arguments in interrupts-in-space files commit 68c6ca4 Author: robotmad <[email protected]> Date: Thu Sep 17 23:51:49 2026 +0100 update as per changes to aw9523b.h commit c987957 Author: robotmad <[email protected]> Date: Thu Sep 17 23:51:04 2026 +0100 Squashed commit of the following: commit a2e7dd0 Author: Chris <[email protected]> Date: Wed Aug 5 22:16:04 2026 +0100 interrupt driven spaceagon buttons, joystick and touch running on interrupts. PMIC status read limited to rate of PMIC ADC (1Hz) commit 3674e33 Author: robotmad <[email protected]> Date: Thu Sep 17 23:46:50 2026 +0100 Merge branch 'i2c-scan-selective' commit beb9122 Author: robotmad <[email protected]> Date: Thu Sep 17 23:40:48 2026 +0100 memory saving from eliminating callback args - hence only need to remember the callback function as pin/port can be reconstructed. commit 398a2ce Author: robotmad <[email protected]> Date: Tue Sep 15 21:25:59 2026 +0100 use TILDAGON_XXX_I2C_PORT definitions in place of magic numbers for I2C mux ports commit 83e1411 Author: robotmad <[email protected]> Date: Tue Sep 15 21:25:32 2026 +0100 GPIO pins via AW9523B: cache output state, direction and mode in RAM. Use tildagon-i2c-manager one-shot C callback job for the last write of any action so that micropython can return and leave that to take place in parallel. FreeRTOS Semaphore used to mange serialisation of I2C access for maximum performance. Move toggle to C layer to take advantage of caching. Update fakes for Pin and ePin. commit ffc479b Author: robotmad <[email protected]> Date: Tue Sep 15 21:23:27 2026 +0100 Frontboard 2026 compass - use tildagon-i2c-manager job for polling. The job only does data transfer - so conversion from raw bytes to meaningful values moved to the read function. commit 78da35e Author: robotmad <[email protected]> Date: Tue Sep 15 21:22:28 2026 +0100 IMU class:: use of tildagon-i2c-manager jobs for I2C polling. get and set_period() methods. Default to sensor I2C polling being Off - automatically activated on first read at 'legacy' rates 40mS for gyro/accelerometer, 1000mS for temperature and steps (now controlled separately from accel/gyro). Uses refactored BMI270 driver. Use of const to reduce RAM use. New tildagon_imu_state_t structure for RAM so that lsm6ds3 and bmi270 don't have duplicate static allocations internally. lsm6ds3 control register set to filter sensor data in sync wtih the intended I2C read poll rate. commit a78d22c Author: robotmad <[email protected]> Date: Tue Sep 15 21:21:32 2026 +0100 support 16 bit addressing of i2c device registers (e.g. SCD4X) commit 5ee12dc Author: robotmad <[email protected]> Date: Tue Sep 15 21:14:29 2026 +0100 tildagon_i2c_manager: new task in place of imu task, supports i2c operations running in parallel wtih micropython for imu, but also any other i2c transaction can now take advantage of this parallelism via C callbacks for C/micropython 'jobs'. micropython API provided for 'jobs' comprising up to 5 steps. READ/WRITE/READ16/WRITE16/CHECK step types. One-Shot (run_once) or Periodic execution with status monitoring and optional 'Pin.irq' style callback upon completion. Support for I2C devices with 8 bit and 16 bit register addressing. 10 slots for I2C callbacks/jobs. Replace extern ad-hoc declarations. commit 9c3948f Author: robotmad <[email protected]> Date: Tue Sep 15 21:01:48 2026 +0100 IMU - refactored minimal bmi270 driver in place of flow3r one, with support for setting read/update period and hence internal filters to match I2C polling period. commit f10ecb8 Author: Sam Machin <[email protected]> Date: Mon Sep 14 22:51:16 2026 +0100 Feat/utc settings (emfcamp#440) * add utc offset to settings * add utc offset to settings * store seconds use offset as label * fix formating commit 1fe0fad Author: Sam Machin <[email protected]> Date: Mon Sep 14 22:21:36 2026 +0100 keyboard enter done in TextDialog (emfcamp#443) Allows the enter key to trigger Done in a TextDialog commit f2f6a3d Author: Matthew Wilkes <[email protected]> Date: Mon Sep 14 22:19:22 2026 +0100 Add RMT RX peripheral (emfcamp#425) Backports micropython/micropython#18454 from MP 1.29 (or later) commit 9b833f0 Author: Sam Machin <[email protected]> Date: Mon Sep 14 21:28:10 2026 +0100 add ntpsync service (emfcamp#442) commit ee80b27 Author: Christopher Barnes <[email protected]> Date: Mon Sep 14 20:19:09 2026 +0100 Change FreeRTOS tick rate to 1mS (emfcamp#456) commit 42c2a0f Author: Sam Machin <[email protected]> Date: Thu Aug 6 22:15:47 2026 +0200 add missing chars in text dialog (emfcamp#433)

elvis-epx force-pushed the rmtrx branch 2 times, most recently from 078969b to 84d4181 Compare November 21, 2025 15:27

This was referenced Dec 9, 2025

RMT read pulses? #15521

Open

RMT receive #16589

Closed

dpgeorge added the port-esp32 label Dec 16, 2025

projectgus self-requested a review December 17, 2025 04:53

projectgus reviewed Jan 21, 2026

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elvis-epx force-pushed the rmtrx branch from 0e7e43f to 40c8209 Compare January 21, 2026 13:59

elvis-epx and others added 4 commits January 26, 2026 16:33

esp32: Add RMT RX module.

743f461

Signed-off-by: Elvis Pfutzenreuter <[email protected]>

esp32: Update docs.

ea218e3

Small fixes and style changes in RMT RX documentation. Co-authored-by: Angus Gratton <[email protected]> Signed-off-by: Elvis Pfützenreuter <[email protected]>

esp32: Fix coding style issues.

5e1aabe

Align the code style to esp32_rmt.c. Signed-off-by: Elvis Pfutzenreuter <[email protected]>

esp32: Add comment on magic constant.

a8d1fbb

Add comment to clarify where the 15-bit value comes from. Signed-off-by: Elvis Pfutzenreuter <[email protected]>

elvis-epx force-pushed the rmtrx branch from 2f9ec07 to 73db95e Compare January 26, 2026 19:35

elvis-epx force-pushed the rmtrx branch from 73db95e to 3bcfe5a Compare January 26, 2026 19:45

elvis-epx requested a review from projectgus January 27, 2026 14:25

elvis-epx force-pushed the rmtrx branch 2 times, most recently from 352036a to 8537c3a Compare January 28, 2026 21:18

projectgus reviewed Feb 3, 2026

View reviewed changes

Comment thread tests/target_wiring/esp32.py Outdated

projectgus added this to the release-1.28.0 milestone Feb 3, 2026

esp32: Add RMT simple test.

2a4ec5c

Add simple end-to-end test for RMT RX, and TX. Signed-off-by: Elvis Pfutzenreuter <[email protected]>

elvis-epx force-pushed the rmtrx branch from 8537c3a to 2a4ec5c Compare February 11, 2026 19:36

dpgeorge modified the milestones: release-1.28.0, release-1.29.0 Mar 27, 2026

MatthewWilkes mentioned this pull request Jul 22, 2026

Add RMT RX peripheral emfcamp/badge-2024-software#425

Merged

dpgeorge modified the milestones: release-1.29.0, release-1.30 Aug 13, 2026

ChrisDick pushed a commit to emfcamp/badge-2024-software that referenced this pull request Sep 14, 2026

Add RMT RX peripheral (#425)

f2f6a3d

Backports micropython/micropython#18454 from MP 1.29 (or later)

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RFC: Add RMT RX module. - #18454

RFC: Add RMT RX module.#18454
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elvis-epx commented Nov 21, 2025

Summary

Testing

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