OpenCentauri FreeRTOS DSP Firmware

This repository contains a modified version of FreeRTOS-HIFI4-DSP adapted for the OpenCentauri project, specifically for the r528 SoC.

How to Use

Prerequisites

1. OpenCentauri v0.0.4 or later.
2. Serial UART connection at 115200 baud.
3. Install the compiler to tools/xtensa-hifi4-gcc/.

Method 1: Serial Console Deployment

1. Compile the firmware:

   make

2. Copy the compiled firmware to your printer's USB stick:

   scp build/dsp.elf carbon:/boot/exUDISK/

3. Set a boot delay in uBoot (via SSH on the mainboard):

   fw_setenv bootdelay 10

4. Add a uBoot command to start the new DSP firmware from the USB stick:

   fw_setenv dsp_oc 'usb start;usb dev 0;fatload usb 0:1 43000000 dsp.elf;bootr 43000000 0 0'

5. Reboot your Centauri, interrupt the boot process when prompted, and enter:

   run dsp_oc
   

6. To boot into Linux afterward, enter:

   run setargs_mmc boot_normal
   

Method 2: Alternate Deployment (No Serial Console)

This method sets the custom DSP firmware as the default, booting from the external USB drive.

1. Build dsp.elf using the instructions above and copy it to /mnt/exUDISK.
2. Ensure /mnt/exUDISK is a vfat partition mounted from /dev/sda1. You can verify with:

   mount | grep sda1
   # Expected output:
   # /dev/sda1 on /mnt/exUDISK type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=utf8,shortname=mixed,utf8,errors=remount-ro)

3. Backup your current uBoot settings!

   fw_printenv > uboot_backup.txt

4. Run these commands to change the default boot process:

   fw_setenv bootdelay 4
   fw_setenv dsp_oc 'usb start;usb dev 0;fatload usb 0:1 43000000 dsp.elf;bootr 43000000 0 0;sleep 2'
   fw_setenv bootcmd "run setargs_mmc dsp_oc boot_normal"

5. Reboot. The device should now boot using dsp.elf from the USB drive.

Rollback

• If the device doesn't boot, you can copy a stock dsp.elf to the USB drive and reboot.
• To restore the default boot from eMMC, run:

  fw_setenv bootcmd "run setargs_mmc boot_dsp0 boot_normal"

Todo

• Port Klipper MCU firmware to this FreeRTOS environment.
• Enable GPIO drivers if they don't already exist/work (examples in upstream Allwinner sources).
• Establish communication between the DSP and the Linux Processing System, possibly via the MsgBox API.

---

Original FreeRTOS-HIFI4-DSP

⚠ NOTE: This is not an official RTOS SDK or Compiler and does NOT support all DSP features.

This is FreeRTOS for the Cadence Tensilica HIFI 4 DSP, using the GCC Compiler.

About the Compiler

The Cadence Tensilica HIFI 4 typically uses Xtensa Xplorer and XCC for development. This project uses GCC instead.

How to Build

1. Clone the repository:

   git clone https://github.com/YuzukiHD/FreeRTOS-HIFI4-DSP.git

2. Download the Compiler and unzip it into the tools directory.
3. Run the make command:

   make

Firmware Loader

SyterKit

SyterKit provides a hifi4 loader: https://github.com/YuzukiHD/SyterKit/tree/main/board/100ask-d1-h/load_hifi4

U-Boot Driver

A U-Boot driver is available to load firmware to the HIFI4 DSP: uboot-driver/dsp