05-14-2026, 09:06 PM
Hi Devin
Thanks for the report.
With the two RCT6 boards I have here (regular iomixer and one dev board from AliExpress) I was able to send MIDI messages to Fedora Linux ok. But both of the two 'blue pill' variants showed the symptoms you describe - the device appears but no message events are received. The 'blue pill' boards use a CBT6 but I don't think that should matter. The other issue we discussed via email (pullups on the USB D+ line inhibiting soft-reset) should not matter either... I think.
Since you're also using a RCT6 the only point of difference seems to be the Linux version. I will try this with Arch Linux next, although that might take a bit longer.
While I was investigating this I noticed some code that was not handling the recent change to support 8MHz properly, so I fixed that. It did not help with my blue pills but there is a small chance it's related to this issue so it's worth giving it a try. I have updated the file here (main app only): https://iomixer.com/releases/firmware/xperimental/8MHz
Since you had it running ok on Windows you probably don't need any help with the configuration side, but for others coming to this thread who are not familiar, I will leave a link to the video you mentioned here: https://www.youtube.com/watch?v=Njruoow2stw
In particular note that the port to use for events going from the iomixer to the PC is "iomixer MIDI out". Also, on Linux using channel 0 in the configurator seems to result in channel 1 in the hardware tester page.
Thanks for the report.
With the two RCT6 boards I have here (regular iomixer and one dev board from AliExpress) I was able to send MIDI messages to Fedora Linux ok. But both of the two 'blue pill' variants showed the symptoms you describe - the device appears but no message events are received. The 'blue pill' boards use a CBT6 but I don't think that should matter. The other issue we discussed via email (pullups on the USB D+ line inhibiting soft-reset) should not matter either... I think.
Since you're also using a RCT6 the only point of difference seems to be the Linux version. I will try this with Arch Linux next, although that might take a bit longer.
While I was investigating this I noticed some code that was not handling the recent change to support 8MHz properly, so I fixed that. It did not help with my blue pills but there is a small chance it's related to this issue so it's worth giving it a try. I have updated the file here (main app only): https://iomixer.com/releases/firmware/xperimental/8MHz
Since you had it running ok on Windows you probably don't need any help with the configuration side, but for others coming to this thread who are not familiar, I will leave a link to the video you mentioned here: https://www.youtube.com/watch?v=Njruoow2stw
In particular note that the port to use for events going from the iomixer to the PC is "iomixer MIDI out". Also, on Linux using channel 0 in the configurator seems to result in channel 1 in the hardware tester page.