Need help to use ESP32 RMT module under Zephyr

[Alex-Stanfield]

Hi there, is it possible to use the RMT module ( https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/rmt.html ) under zephyr? I'm new to zephyr but managed already to try some sample code with zephyr.

I need to output a square wave with variable frequency in order to control stepper motors (simple direction & clock lines). I need to ramp-up, flat, slow-down the speed and have a precise number of steps so I thought a HW solution (RMT) with SW supervision (via interrupts) would be fine, however I didn't find the zephyr implementation to use RMT module. Maybe I missed something?

I'm using the esp32_devkitc_wroom board.

Thanks in advance
Alex

[rftafas]

Hi!

RMT is not supported yet. We do support LedPWM and MCPWM for such applications. If you MUST use RMT, then your options:

• DIY, You should use hal_espressif LL APIs to write a zephyr driver for RMT.
• Open a feature request and wait
• Use another OS that supports it (NuttX, ESP-IDF)

FWIW, it is on our backlog, but not scheduled on Q2 and Q3 of 24. Main reason is that the mentioned peripherals can cover for this application.

[Alex-Stanfield]

Thanks for all responses. I’ll look into ledpwm and mcpwm guess. Thanks Sds, Alex

…

On Tue, 2 Apr 2024 at 09:24 Ricardo F Tafas Jr ***@***.***> wrote: Hi! RMT is not supported yet. We do support LedPWM and MCPWM for such applications. If you MUST use RMT, then your options: - DIY, You should use hal_espressif LL APIs to write a zephyr driver for RMT. - Open a feature request and wait - Use another OS that supports it (NuttX, ESP-IDF) FWIW, it is on our backlog, but not scheduled on Q2 and Q3 of 24. Main reason is that the mentioned peripherals can cover for this application. — Reply to this email directly, view it on GitHub <#70575 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADYNY7CF2VUZIUBZ66OZU7TY3KPPXAVCNFSM6AAAAABFCCJ6QGVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM4DSOBTGM3DO> . You are receiving this because you authored the thread.Message ID: ***@***.*** com>

[LuskeyNoah]

@Alex-Stanfield I started working a bit on porting the RMT peripheral into the Zephyr driver model in this issue: vvvvvvvvvv-LLC/t-watch-s3#8 (a project of mine). Although the driver is "out-of-tree", I have structured it in such a way that it could be upstreamed to Zephyr.

If that is interesting to you, I would absolutely love some help there. Most of the structure is there, but almost none of the implementation. I didn't really see any existing driver-APIs that were a good match for the RMT peripheral, so I created a new driver-API named rmt_tx. If you have any suggestions for a base driver-API that maps well to the idea of transmitting arbitrary data and configuring a carrier, I'm open to suggestions.

Anyway, I'm pausing work on this for a bit to focus on some other features, but again, would love some help if it's interesting to you (or @rftafas )