Hello everyone,
With the recent momentum around multichannel audio on TDM/USB, I wanted to introduce a project that I've been working on for several years. I've kept it under wraps until now due to some commercial interests, but I believe that both the community and my project can benefit greatly from some open discussion about it. I’m curious if there might be a demand for this, and perhaps we could even explore the possibility of a group build.
Recently, I decided to scale back from the full-blown digital motherboard concept and integrate the same ideas into smaller, more specialized boards. This T-DSP Audio Board helped me to get my bearings on this project's best design format. I rethought my design strategy of including all audio jacks on the sub-modules and instead designed a universal codec module that can be integrated into a custom backplane, which then exposes the audio ports. In this new approach, the "motherboard" is still helpful. The backplane can get as complex as a standard board if someone tries to integrate some of the digital functions into the backplane. Also, this way we get natural isolation of digital and analog ground planes. With the backplane concept, having four TDM expansion headers turns out to be less necessary since we could rework the expansion modules to contain all five serial audio lines and then "select" the appropriate line on the backplane depending on the configuration required by each use-case. These backplanes could be easily shared for different use-cases.
The SAI2 is directly connected to the ESP32. AFAIK, the ESP32 has limited TDM functionality at the moment. Theoretically, the ESP32 could bridge additional modules via its other I2S port, or if we designate the SAI2 for the ESP32 and a codec, the motherboard could provide out-of-the-box audio functionality, leaving the expansion ports as simply auxiliary. If we did a group buy, this would allow us all to work on the software together to make it all work seamlessly. The ESP32 could theoretically expose the audio design tool via a server running on the MCU. This would allow us to control the device via Bluetooth or Wi-Fi on desktop or even mobile. These are just some ideas I’ve been exploring.
The expansion headers are FreeDSP compatible (as of now), and the Teensy community might be able to contribute to that audience too if we were to open this up to that community as a joint project. They had relatively recent success with the FreeDSP-Aurora, but the project stalled (last time I checked) due to the codec getting discontinued. This is yet another reason to separate the motherboard from the modules. That community currently relies on Analog Devices Sharc processors, but there is nothing in the organization's rules that says we couldn't introduce a new DSP model based on the IMXRT1060. It sure would be interesting to have a community-contributed audio development solution for pretty much anything audio, such as audio mixers, processors, recorders, converters, distributors, transceivers, instruments, art installations, etc.—the same stuff you are already doing here in this community. How can we work this project to jump-start some amazing projects?
Thanks for taking the time to read this, and I look forward to any discussions that may follow!
Best regards,
Jay Shoemaker
With the recent momentum around multichannel audio on TDM/USB, I wanted to introduce a project that I've been working on for several years. I've kept it under wraps until now due to some commercial interests, but I believe that both the community and my project can benefit greatly from some open discussion about it. I’m curious if there might be a demand for this, and perhaps we could even explore the possibility of a group build.
Project Overview:
This project centers around a board that exposes all of the TDM lines and aims to implement as many viable functions as possible through the audio library. What sets it apart from some other projects is that it distributes the audio lines digitally, which allows for modular functionality. I’ve developed sub-modules for various ADCs, DACs, and codecs, and I’ve designed a PCB-based case that I’m quite proud of. The main idea is to expose everything the audio library can do to help users create custom audio projects.Design Evolution:
This has been a massive undertaking, and while I do want to contribute to the community, I’m still figuring out the best way to do so. I also recognize and appreciate the incredible work done by many other users here—cheers and kudos to all of you! There’s a significant amount of software required to make all the available functions work in a meaningful way, and I realize that keeping this project in my pocket without any major progress is a waste of time.Recently, I decided to scale back from the full-blown digital motherboard concept and integrate the same ideas into smaller, more specialized boards. This T-DSP Audio Board helped me to get my bearings on this project's best design format. I rethought my design strategy of including all audio jacks on the sub-modules and instead designed a universal codec module that can be integrated into a custom backplane, which then exposes the audio ports. In this new approach, the "motherboard" is still helpful. The backplane can get as complex as a standard board if someone tries to integrate some of the digital functions into the backplane. Also, this way we get natural isolation of digital and analog ground planes. With the backplane concept, having four TDM expansion headers turns out to be less necessary since we could rework the expansion modules to contain all five serial audio lines and then "select" the appropriate line on the backplane depending on the configuration required by each use-case. These backplanes could be easily shared for different use-cases.
The SAI2 is directly connected to the ESP32. AFAIK, the ESP32 has limited TDM functionality at the moment. Theoretically, the ESP32 could bridge additional modules via its other I2S port, or if we designate the SAI2 for the ESP32 and a codec, the motherboard could provide out-of-the-box audio functionality, leaving the expansion ports as simply auxiliary. If we did a group buy, this would allow us all to work on the software together to make it all work seamlessly. The ESP32 could theoretically expose the audio design tool via a server running on the MCU. This would allow us to control the device via Bluetooth or Wi-Fi on desktop or even mobile. These are just some ideas I’ve been exploring.
The expansion headers are FreeDSP compatible (as of now), and the Teensy community might be able to contribute to that audience too if we were to open this up to that community as a joint project. They had relatively recent success with the FreeDSP-Aurora, but the project stalled (last time I checked) due to the codec getting discontinued. This is yet another reason to separate the motherboard from the modules. That community currently relies on Analog Devices Sharc processors, but there is nothing in the organization's rules that says we couldn't introduce a new DSP model based on the IMXRT1060. It sure would be interesting to have a community-contributed audio development solution for pretty much anything audio, such as audio mixers, processors, recorders, converters, distributors, transceivers, instruments, art installations, etc.—the same stuff you are already doing here in this community. How can we work this project to jump-start some amazing projects?
Request for Feedback:
I’m genuinely interested in hearing your thoughts on this project. Whether it’s suggestions on how best to open-source it, potential interest in a group build, or any other feedback you might have, I’m all ears. I know that sharing this project with the community could lead to exciting developments, and I’m eager to see where it could go with your input.Thanks for taking the time to read this, and I look forward to any discussions that may follow!
Best regards,
Jay Shoemaker