Add support for CH32X035 architecture #324

NoNamedCat · 2026-01-16T21:06:25Z

This PR adds full support for the WCH CH32X035 RISC-V microcontroller.

Changes:

Added IS_CH32() macro in hardware_defines.h.
Added platform-specific implementation in internal/MozziGuts_impl_CH32.hpp.
Added configuration checks in internal/config_checks_CH32.h and registered them in internal/config_checks_generic.h.

Typo

parameter hence allowing for differently sized bufers to be used (for instance with audio input)

Removed old todo

Includes platform definitions, configuration checks, and core implementation for CH32 architecture.

… and check specifically for CH32X035 in implementation.

…s and guts implementation).

Smaller audio buffers config option

…Mozzi into feat/ch32-support-standalone

tomcombriat · 2026-01-17T18:17:31Z

Hi,
Thanks very much for this.

I tried to compile some of my sketches locally, but the platform is not recognized on my IDE. I installed support for the board by using this core: https://github.com/openwch/arduino_core_ch32. What is the core you use?

Also, I saw that the PR concerning FixMath has been dropped, is it not needed after all?

NoNamedCat · 2026-01-18T07:41:19Z

Yeah is not needed. I have done some test without the FixMath PR and the library compile without that. Im using this URL for the board manager: https://github.com/openwch/board_manager_files/raw/main/package_ch32v_index.json.

Also I think that you will like this:

https://nonamedcat.github.io/MozziFlowEditor/

sensorium · 2026-01-18T11:03:37Z

Hey @NoNamedCat, the Flow Editor is awesome!

tomcombriat · 2026-01-18T18:31:59Z

Hi again,
I was using the same core but for some reason, in the Arduino IDE, the hardware define was not the same. I added one option there so that it does now compile there. Sorry for messing completely up the number of commits, this is due to merging your branch with Mozzi's master branch.

I can't unfortunately test it entirely because of lack of hardware, but I will try to have a close look soon!

The Flow Editor is neat! I did not manage to get the code updated from what is in the flow, it remains a blank script… Am I missing something?

tomcombriat

Left a few comments on some details. Also, bonus if you can add documentation for the website (both README.md and extras/website/index.markdown).

Interesting platform, I have to get my hand on one!

Also, with a platform with that many ADC channels, do you have plan to implement async ADC reads?

tomcombriat · 2026-01-18T18:33:45Z

internal/MozziGuts_impl_CH32.hpp

+ * MozziGuts_impl_CH32.hpp
+ *
+ * Implementation for WCH CH32X035 (RISC-V) using Standard Peripheral Library (SPL)
+ *


Maybe add your name/pseudo here?

There’s no need to include my pseudonym in the code or anywhere else. I just want to give back to the community that has given me so much (and while I’m at it, I’d like to say thank you for the Mozzi library and FixMath as well).
Asynchronous analog readings are definitely something that could improve this a lot, and I should implement them.
Right now, the port for this architecture works as it is, and I think it’s good enough for an initial release, but I’m definitely keeping this in mind.

Of course that's up to you, but most of Mozzi's files display such information, which also shows that this is a collaborative effort and helps to track back when things were done and who might be the expert. A new port is always a good thing :).
As per the ADC, I fully agree that this should go in without waiting for async.

tomcombriat · 2026-01-18T18:39:59Z

internal/MozziGuts_impl_CH32.hpp

+    long out = (long)f.l() + MOZZI_AUDIO_BIAS;
+
+    // Clamp to 16-bit unsigned range just in case
+    if (out < 0) out = 0;


I would think this is un-necessary: having a check for every sample will incur some drawbacks on the CPU. Other platforms don't do it so users are usually used to take care of overflows.

You are right

tomcombriat · 2026-01-18T18:41:45Z

internal/MozziGuts_impl_CH32.hpp

+    long out = (long)f.l() + MOZZI_AUDIO_BIAS; 
+    if (out < 0) out = 0;
+    out = out >> (MOZZI_AUDIO_BITS - 8); 
+    if (out > 255) out = 255;


Again. You are right.

NoNamedCat · 2026-01-19T04:51:12Z

Left a few comments on some details. Also, bonus if you can add documentation for the website (both README.md and extras/website/index.markdown).

Interesting platform, I have to get my hand on one!

Also, with a platform with that many ADC channels, do you have plan to implement async ADC reads?

I can share the KiCad design files for the 28-pin board I'm using, or you can buy some ready-made boards on AliExpress.
This chip is really awesome for the price.
I've written several libraries for using its USB hardware (MIDI, HID mouse, HID gamepad, HID keyboard, and HID Composite — which combines mouse, keyboard, and gamepad at the same time).
I really like this chip, but since it's relatively new, I'm trying to make it more usable for my own projects while sharing everything I create with the community along the way.

NoNamedCat · 2026-01-19T04:53:15Z

Hi again, I was using the same core but for some reason, in the Arduino IDE, the hardware define was not the same. I added one option there so that it does now compile there. Sorry for messing completely up the number of commits, this is due to merging your branch with Mozzi's master branch.

I can't unfortunately test it entirely because of lack of hardware, but I will try to have a close look soon!

The Flow Editor is neat! I did not manage to get the code updated from what is in the flow, it remains a blank script… Am I missing something?

I broke so many things in a PR without knowing. Now is fixed.

tomcombriat · 2026-01-19T05:33:05Z

internal/config_checks_CH32.h

+// Configure Audio Bits based on Mode
+#if MOZZI_IS(MOZZI_AUDIO_MODE, MOZZI_OUTPUT_PWM)
+    #if !defined(MOZZI_AUDIO_BITS)
+    #define MOZZI_AUDIO_BITS 16 // Internal calc at 16, output scaled to 8


Also, why not setting that to 8 in order first to be clearer about the output but also to avoid one extra shift in the output?

I was trying out some computations with the 32-bit ALU in the MCU to help reduce noise in a Mozzi sketch prior to audio output, and I simply forgot to clean it up afterward. Thanks for catching that!

Implemented ADC1_IRQHandler and setupFastAnalogRead for CH32X035 using direct SPL calls. Added robust pin-to-channel mapping fallback logic.

Fixed RCC and ADC function names, removed non-existent calibration calls, and updated sample time constants to match WCH core v1.0.4. Verified compilation with arduino-cli.

NoNamedCat · 2026-01-21T00:03:08Z

Now the Mozzi output configuration is set correctly (8-bit). I've made the changes you requested and have also been working extensively on MozziFlowEditor. It now exports much cleaner code. I've also implemented non-blocking analog reads. I've tested several example patches, and they seem to work well, but this still requires a lot of testing. I'll keep working on it in my spare time, though I expect to be very busy for at least the next couple of weeks. Any feedback bugs, suggestions, or anything else is welcome!

NoNamedCat · 2026-01-23T14:45:42Z

@tomcombriat. The port for the CH32X035 is now finished and stable. I have performed many test on actual hardware, and everything is functioning correctly, including the asynchronous ADC implementation.

tomcombriat · 2026-01-23T14:54:44Z

@NoNamedCat This is great, the addition of async ADC makes a lot of sense on such a board I think. Thank you very much for all of this. I also saw that you updated the documentation which is super.
I have very little time these days, for personal reasons, so I won't have the time to review thoughtfully any time soon. The fact that all the checks are passing indicates that nothing else is obviously broken, so I think this can likely go in with no or little change but I think it would still be nice if @sensorium or @tfry-git or me have the time to have a quick look before.

Thanks again

tomcombriat and others added 17 commits April 18, 2025 19:27

Initial changes to CircularBuffer for smaller buffer sizes

fe17896

Typo

Started documentation of MOZZI_BUFFER_SIZE

98e9cc7

Changed MOZZI_BUFFER_SIZE to MOZZI_OUTPUT_BUFFER_SIZE

1c46911

Added generic config

3d6c5ea

Modified CircularBuffer to have the buffer size as a template

ff7b782

parameter hence allowing for differently sized bufers to be used (for instance with audio input)

Updated MozziGuts for different buffer size

ba78571

Fix Renesas compilation with MOZZI_OUTPUT_BUFFER_SIZE

8c1a6e7

FixESP8266 I2S

9ecdd09

Added warning messages when defining a smaller does not have an effect

aa967f1

Removed old todo

Merge branch 'master' into dev/small_buffer

04b3263

Merge remote-tracking branch 'upstream/master' into dev/small_buffer

78ebf73

Add support for CH32X035 microcontrollers

f7cf290

Includes platform definitions, configuration checks, and core implementation for CH32 architecture.

Refine platform detection macros: use ARDUINO_ARCH_CH32V for IS_CH32,…

a034090

… and check specifically for CH32X035 in implementation.

Ensure CH32 headers are included in generic dispatchers (config check…

468b0ec

…s and guts implementation).

Merge pull request sensorium#308 from sensorium/dev/small_buffer

3e45eab

Smaller audio buffers config option

Increase version number

a621383

Merge branch 'feat/ch32-support-standalone' of github.com:NoNamedCat/…

4d4f43a

…Mozzi into feat/ch32-support-standalone

Fix compilation for CH32

d7a80c7

tomcombriat reviewed Jan 18, 2026

View reviewed changes

tomcombriat reviewed Jan 19, 2026

View reviewed changes

NoNamedCat added 4 commits January 20, 2026 10:15

feat(ch32): implement non-blocking analog read support

bf55f56

Implemented ADC1_IRQHandler and setupFastAnalogRead for CH32X035 using direct SPL calls. Added robust pin-to-channel mapping fallback logic.

chore: enable MOZZI_ANALOG_READ_STANDARD by default for CH32

a0d1678

fix(ch32): align ADC implementation with CH32X035 SPL

05570d5

Fixed RCC and ADC function names, removed non-existent calibration calls, and updated sample time constants to match WCH core v1.0.4. Verified compilation with arduino-cli.

Fixed CH32X035 ADC resolution definition to 12-bit

0678911

Add support for CH32X035 architecture #324

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Add support for CH32X035 architecture #324

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