@Eric-Katzfey Thanks for your response, I appreciate you taking some time to think about this.

Apologies, when I said voxl-px4, I think of this as the binary that runs on the DSP, but I guess it is both the Apps and the DSP split application.

Shifting to the Apps processor isn't an option for this particular use-case but I appreciate that I may have more control / insight doing this from Linux.

Can you point me to any datasheets that I can try to access from Qualcomm which may shed some light on both the capabilities of the Sensor Hexagon DSP and the hardware access? I have a Qualcomm account to access their provided documentation and I've unfortunately not found anything useful with the underlying RTOS and practically nothing on the drivers for the UART or even how they are connected apart from the mapping in the QUP. Thanks!

Hello,

Platform: VOXL2 running PX4

I have a custom application running on the DSP in the form of a PX4 driver. It is talking over the RC UART port on the VOXL2 to a micro-controller. When I begin increasing the amount of data I am sending into the DSP (from the micro), information starts getting lost on the DSP RX side. I believe it is single bytes getting dropped but I can't rule out multiple bytes also. This happens at 460800, 921600 and 2000000 baud (slower rates are not viable for this application) and I tried varying how frequently I read data from the file handle which doesn't appear to affect anything. The data rate that I've observed issues happening can be as low as 5 KB/s and gets worse with higher rates.

In back-tracing this issue, I've come up with some questions I'd like some help with:

• Which of the DSPs is PX4 running on?
  • I'm assuming the Sensor Hexagon DSP or is it running across multiple DSPs?
  • The entire voxl-px4 stack is running on the QRT1 RTOS isn't it?
• When are the uart function pointers mapped and is the source for these available (I'm assuming no)?
• What is the underlying configuration of the UART that the DSP is talking to on the RC Port?
  • Is there a library or config file where I can inspect the config / setup?
  • For the low-level IO, is there a DMA in place and what is the buffer size?
    • Could this be an issue?
• Is there documentation or architecture diagrams covering these details?
  • Unfortunately I could not find the necessary information in the forums or on the docs site

Best Regards,
Shaun.