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Ox64 full documentation



The Ox64 is a RISC-V based single-board computer based on the Bouffalo Lab BL808 RISC-V SoC with C906 64-bit and E907/E902 32-bit CPU cores supported by 64 MB of embedded PSRAM memory, and with built-in WiFi, Bluetooth and Zigbee radio interfaces. The Ox64 comes in a breadboard-friendly form-factor, has a microSD card slot, a USB 2.0 Type-C port, and many other peripheral interfaces for makers to integrate with sensors and other devices.

The Ox64

Pinout of the production version


Features

Network

  • 2.4 GHz 1T1R WiFi 802.11 b/g/n
  • Bluetooth 5.2
  • Zigbee
  • 10/100 Mbit/s Ethernet (optional, on expansion board)

Storage

  • On-board 16 Mbit (2 MB) or 128 Mbit (16 MB) XSPI NOR flash memory
  • MicroSD - supports SDHC and SDXC (only on the 128 Mb version)

Expansion Ports

  • USB 2.0 OTG port
  • 26 GPIO pins, including SPI, I~2~C and UART functionality, possible I~2~S and GMII expansion
  • Dual-lane MiPi CSI port, located at USB-C port, for camera module

Audio

  • Microphone (optional, on the camera module)
  • Speaker (optional, on the camera module)

Software

Releases

There is a community effort to bring updated kernels, peripherals and buildroot - Lots of communication happening in the #ox64-nutcracker channel.

  • buildroot bringing all the work below together with a bootable kernel and updated filesystem images for SD cards
  • U-Boot and OpenSBI work by Smauel
  • Kernel IRQChip, SDCard, and (WIP) USB by arm000, Alexander Horner and others
  • OpenBouffalo Firmware low_load drivers by Fishwaldo and others

Original Linux Images provided by Bouffalo - Very basic alpha build which are only fit for board bring up and testing purposes.

Toolchain:

  • elf_newlib_toolchain/bin/riscv64-unknown-elf-gcc (Xuantie-900 elf newlib gcc Toolchain V2.2.5 B-20220323) 10.2.0
  • linux_toolchain/bin/riscv64-unknown-linux-gnu-gcc (Xuantie-900 linux-5.10.4 glibc gcc Toolchain V2.2.4 B-20211227) 10.2.0
  • cmake version 3.19.3

Software Development Kits

Building

Start the building process cloning both the upstream Buildroot repository and the Buildroot Bouffalo overlay repository:

 $ mkdir -p ~/ox64
 $ cd ~/ox64
 $ git clone https://github.com/buildroot/buildroot
 $ git clone https://github.com/openbouffalo/buildroot_bouffalo

Define an environment variable for the Buildroot Bouffalo overlay path:

$ export BR_BOUFFALO_OVERLAY_PATH=$(pwd)/buildroot_bouffalo

Change directory into the cloned Buildroot folder:

$ cd ~/ox64/buildroot

Apply the default configuration for Pine64 Ox64:

$ make BR2_EXTERNAL=$BR_BOUFFALO_OVERLAY_PATH pine64_ox64_defconfig

Use the menuconfig tool to adjust the build settings:

$ make menuconfig

Within menuconfig, configure the following:

  • Select Target Options
  • Enable Integer Multiplication and Division (M)
  • Enable Atomic Instructions (A) using space key
  • Enable Single-precision Floating-point (F)
  • Enable Double-precision Floating-point (D)
  • Select Target ABI, set it to lp64d and press Exit
  • Select Toolchain, enable Fortran support, enable OpenMP support, and Save & Exit

Initiate the build process, but first make sure that your PATH variable contains no spaces. For Arch Linux distrubution you may also need to install extra-packages with sudo pacman -S cpio rsync bc.

$ make

Buildroot will output the needed files to the ~/ox64/buildroot/output/images directory in about 1 hour, according to your computer processing resources and internet connection speed.

Flashing

This page explains how to flash an Ox64 board and a microSD card to boot the system. You will need a Linux computer, a serial UART adapter, the Ox64 board, and a microSD card.

Prepare images for flashing

Download the Ox64 images from the latest OpenBouffalo release. You may skip this step if you built your own images as per the instructions in the Building page.

$ mkdir -p ~/ox64/openbouffalo
$ cd ~/ox64/openbouffalo
$ wget https://github.com/openbouffalo/buildroot_bouffalo/releases/download/v1.0.1/bl808-linux-pine64_ox64_full_defconfig.tar.gz
$ tar -xvzf bl808-linux-pine64_ox64_full_defconfig.tar.gz
$ cd ~/ox64/openbouffalo/firmware
$ xz -v -d -k sdcard-pine64_ox64_full_defconfig.img.xz
$ mv sdcard-pine64_ox64_full_defconfig.img sdcard.img

Optional: create a combined SoC image

Use the following commands to combine m0_lowload_bl808_m0.bin, d0_lowload_bl808_d0.bin, and bl808-firmware.bin into a single image. This is mainly useful for troubleshooting (e. g. when using DevCube v1.8.4 or later).

$ cd ~/ox64/openbouffalo/firmware # if you downloaded pre-built images
 # or
$ cd ~/ox64/buildroot/output/images # if you built your own images

$ fallocate -l 0x800000 bl808-combined.bin
$ dd conv=notrunc if=m0_lowload_bl808_m0.bin of=bl808-combined.bin
$ dd conv=notrunc if=d0_lowload_bl808_d0.bin of=bl808-combined.bin seek=$((0x100000))B
$ cat bl808-firmware.bin >> bl808-combined.bin

Check that you have the required files for flashing

$ cd ~/ox64/openbouffalo/firmware # if you downloaded pre-built images
 # or
$ cd ~/ox64/buildroot/output/images # if you built your own images

$ ls -1 *808*.bin *.img

Expected files:

  • bl808-combined.bin – If you created the combined image.
  • bl808-firmware.bin – OpenSBI and UBoot DTB files. Runs on the D0 core.
  • d0_lowload_bl808_d0.bin – Startup code for the D0 core.
  • m0_lowload_bl808_m0.bin – Startup code for the M0 core.
  • sdcard.img – Kernel and root filesystem. Runs on the D0 core.

Set up your UART adapter

In this section we will configure and wire up a UART adapter in order to flash the Ox64. Choose one of the options below based on the hardware available to you; the first two are the most convenient since they minimise the number of times you will need to swap electrical connections.

Option 1: Raspberry Pi Pico

First, download the Raspberry Pi Pico firmware that allows it to act as a serial UART adapter:

$ mkdir -p ~/ox64/pico
$ cd ~/ox64/pico
$ wget https://github.com/Kris-Sekula/Pine64_Ox64_SBC/raw/main/uart/picoprobe.uf2

Put the Raspberry Pi Pico board into programming mode:

  • Press the BootSel button
  • Apply power by plugging the USB cable to PC
  • Release the BootSel button

note

As an alternative to pressing the BootSel button, you can also connect the probe point TP6 (located on the bottom of the Pico board) to any ground point (e. g. pin 28).

The Pico will now appear as a USB mass storage device. Copy the UF2 file to program it:

$ cp ~/ox64/pico/picoprobe.uf2 /media/<user>/RPI-RP2

Next, connect the Ox64 board to the Pico according to the following wiring diagram:

Ox64PI PICO/dev/tty
uart0_Tx_GPIO14_pin1uart0_Rx_pin17ACM1 for flashing
uart0_Rx_GPIO15_pin2uart0_Tx_pin16ACM1 for flashing
Rxd_GPIO17_pin31uart1_Tx_pin6ACM0 for serial console
Txd_GPIO16_pin32uart1_Rx_pin7ACM0 for serial console
gnd_pin38gnd_pin38/3
vbus5v_pin40vbus5v_pin40

With the Pico flashed and wired as per the instructions above, we have access to two of the Ox64’s UART ports at the same time. This configuration eliminates the need to switch the physical connections for flashing or testing the system.

Reconnect the Pico to your computer’s USB port and verify that we have access to all the serial ports we need:

$ ls /dev/ttyACM*

Expected result:

  • /dev/ttyACM0 connects to the D0 core’s (i.e. Linux’s) serial console
  • /dev/ttyACM1 is used for flashing (but also connects to the M0 core’s serial console)

Option 2: STM32 Bluepill

The Bluepill is an affordable STM32 development board, based on the STM32F103C8T6 chip. We can program it to act as a USB serial adapter, just like we did with the Raspberry Pi Pico.

note

The one catch is that you already need a serial adapter in order to program your Bluepill board. The good news is that you serial adapter does not have to be one from from the Compatible UARTs list. These programming instructions have been tested with a FT232RL adapter (which, notably, is listed as not supported on that list).

If you own an SWD-capable debugger (ST-Link, J-link, etc.) you can use that for programming the Bluepill as well, although instead of stm32flash console command you would be using openocd or other suitable software.

warning

Your serial adapter must use 3.3V logic levels.

Install software to flash Bluepill. For Debian-based systems just install package from repository:

$ sudo apt install stm32flash

For Arch Linux systems, use the AUR repository:

$ mkdir -p ~/ox64/bluepill
$ cd ~/ox64/bluepill
$ git clone https://aur.archlinux.org/stm32flash.git
$ cd ~/ox64/bluepill/stm32flash
$ makepkg -si

Download the Bluepill Serial Monster firmware:

$ mkdir -p ~/ox64/bluepill
$ cd ~/ox64/bluepill
$ wget https://github.com/r2axz/bluepill-serial-monster/releases/download/v2.6.4/bluepill-serial-monster.hex

Put the Bluepill into programming mode:

  • Set boot jumpers for booting from rom: Boot0=1, Boot1=0.
  • Connect it to a USB-Serial adapter with A9 to Rx, A10 to Tx, GND to GND, 3v3 to Vcc.
  • Apply power by plugging the USB cable to PC. Press the Reset button.

Find your USB serial adapter’s device path with ls /dev/ttyUSB* /dev/ttyACM* (or similar); for the rest of this section we will refer to it as /dev/tty[DEVICE]. Upload the firmware:

$ cd ~/ox64/bluepill
$ sudo stm32flash -w bluepill-serial-monster.hex /dev/tty[DEVICE]

After upload, set boot jumpers for boot from flash: Boot0=0, Boot1=0. Disconnect the USB serial adapter from both the PC and Bluepill board.

Next, connect the Ox64 board to the Bluepill according to the following wiring diagram:

Ox64Bluepill/dev/tty
uart0_Tx_GPIO14_pin1uart0_Rx_A3ACM1 for flashing
uart0_Rx_GPIO15_pin2uart0_Tx_A2ACM1 for flashing
Rxd_GPIO17_pin31uart1_Tx_A9ACM0 for serial console
Txd_GPIO16_pin32uart1_Rx_A10ACM0 for serial console
gnd_pin38GND
vbus5v_pin405V

With the Bluepill flashed and wired as per the instructions above, we have access to two of the Ox64’s UART connections at the same time. This configuration eliminates the need to switch the physical connections for flashing or testing the system.

Connect the Bluepill to your computer’s USB port and verify that we have access to all the serial ports we need:

$ ls /dev/ttyACM*

Expected result:

  • /dev/ttyACM0 connects to the D0 core’s (i.e. Linux’s) serial console
  • /dev/ttyACM1 is used for flashing (but also connects to the M0 core’s serial console)
  • /dev/ttyACM2 (unused)

Option 3: Generic UART adapter

Ox64 pinout

Check that your serial adapter is on the Compatible UARTs list. You will (most likely) only have one serial interface available to you; unlike the previous options you will be using this same serial interface for both flashing and testing the system.

Find its device path with ls /dev/ttyUSB* /dev/ttyACM* (or similar); for the rest of this section we will refer to it as /dev/tty[DEVICE].

You will also need a way of powering your Ox64. If your serial adapter has a 5V line, you can connect it to VBUS (pin 40). Otherwise, you can connect either the micro-B or the USB-C port on the Ox64 to any 5V power supply.

warning

Your serial adapter must use 3.3V logic levels.

Refer to the pinout image below. Connect your UART adapter as follows:

  • RX -> UART0_TX / GPIO14 / pin 1
  • TX -> UART0_RX / GPIO15 / pin 2
  • GND -> any ground (e. g. pin 3)

Proceed with the instructions in the sections that follow, up to and including flashing_the_ox64 and flashing_the_microsd_card, but replace all occurrences of /dev/ttyACM1 with /dev/tty[DEVICE].

Next, power off the Ox64 and re-connect your UART adapter as follows:

  • RX -> TXD / GPIO16 / pin 32
  • TX -> RXD / GPIO17 / pin 31
  • GND -> any ground (e. g. pin 33)

Then, follow the instructions in booting_for_the_first_time, but replace all occurrences of /dev/ttyACM0 with /dev/tty[DEVICE]. You should then have a working Linux system.

Download flashing tools

You have a choice of flashing software:

  • DevCube: GUI-based closed source flashing tool
  • CLI (bflb-iot-tool): command line open source flashing tool

DevCube installation

Download the latest DevCube flashing tool from BouffaloLab’s website:

$ mkdir -p ~/ox64/devcube
$ cd ~/ox64/devcube
$ wget https://dev.bouffalolab.com/media/upload/download/BouffaloLabDevCube-v1.8.9.zip
$ unzip BouffaloLabDevCube-v1.8.9.zip
$ chmod u+x BLDevCube-ubuntu

If you did not create a combined image you may need an older version of the DevCube. In that case, download v1.8.3 from one of the mirrors below:

Verify that your copy of BouffaloLabDevCube-v1.8.3.zip matches the hashes below:

  • SHA1: 0f2619e87d946f936f63ae97b0efd674357b1166
  • SHA256: e6e6db316359da40d29971a1889d41c9e97d5b1ff1a8636e9e6960b6ff960913

CLI packages installation

Install bflb-iot-tool using your preferred method of managing PIP packages. One option is to set up a Python virtual environment as follows:

$ sudo apt install pipenv # for Debian-based systems
 # or
$ sudo pacman -S python-pipenv # for Arch Linux systems

$ cd ~/ox64/
$ pipenv install setuptools # install prerequisite of CLI flash tool
$ pipenv install bflb-iot-tool # install CLI flash tool
$ pipenv shell # activate virtual environment
$ # bflb-iot-tool --help # return info about the tool

note

Each time you open a new terminal window you will need to cd ~/ox64/ and re-run pipenv shell to reactivate the virtual environment.

Flashing the Ox64

Put the Ox64 into programming mode:

  • Press the BOOT button
  • Apply power or re-plug the USB cable
  • Release the BOOT button

CLI flashing method

Set up some environment variables to save typing them out later:

$ cd ~/ox64/openbouffalo/firmware # if you downloaded pre-built images
 # or
$ cd ~/ox64/buildroot/output/images # if you built your own images

$ PORT=/dev/ttyACM1
$ BAUD=230400  # safe value for macOS, set to 2000000 for faster flashing on Linux

Finally, flash the Ox64. If you created a combined image then run the command below:

$ bflb-iot-tool --chipname bl808 --interface uart --port $PORT --baudrate $BAUD \
>               --addr 0x0 --firmware bl808-combined.bin --single

Otherwise, run the following commands:

$ bflb-iot-tool --chipname bl808 --interface uart --port $PORT --baudrate $BAUD \
>               --addr 0x0 --firmware m0_lowload_bl808_m0.bin --single

$ bflb-iot-tool --chipname bl808 --interface uart --port $PORT --baudrate $BAUD \
>               --addr 0x100000 --firmware d0_lowload_bl808_d0.bin --single

$ bflb-iot-tool --chipname bl808 --interface uart --port $PORT --baudrate $BAUD \
>               --addr 0x800000 --firmware bl808-firmware.bin --single

If you get permission errors when running any of the commands above, run ls -l /dev/tty[DEVICE], to find out which group is allowed to talk to serial ports and add your user to that group, with sudo usermod -a -G [GROUP] $USER (i.e. dialout for Debian or uucp for Arch Linux). Make sure you re-login. Running the commands as root is not recommended since this will make bflb-iot-tool create root-owned files in your home directory. You can now run exit from virtual environment.

BLDevCube flashing method

Open a new terminal window to run the DevCube flasher:

$ cd ~/ox64/devcube
$ ./BLDevCube-ubuntu

Select chip [BL808], press Finish, and configure BOTH the [MCU] and [IOT] tabs as follows. When you switch between tabs double check that they still match the settings below:

InterfaceUART
Port/SN/dev/ttyACM1
UART rate230400 (safe value for macOS, set to 2000000 for faster flashing on Linux)

If you created a combined image then you only need to use the [IOT] tab:

  • Enable ‘Single Download’
  • Image Address [0x0], [PATH to bl808-combined.bin]
  • Click ‘Create & Download’ and wait until it’s done
  • Close DevCube

Otherwise, start in the [MCU] tab:

  • M0 Group[group0], Image Address [0x58000000], [PATH to m0_lowload_bl808_m0.bin]
  • D0 Group[group0], Image Address [0x58100000], [PATH to d0_lowload_bl808_d0.bin]
  • Click ‘Create & Download’ and wait until it’s done

Then, switch to the [IOT] tab:

  • Enable ‘Single Download’
  • Image Address [0x800000], [PATH to bl808-firmware.bin]
  • Click ‘Create & Download’ again and wait until it’s done
  • Close DevCube

Erasing the microSD card

Make sure there are no signatures or partitions left, and overwrite the first sectors with zeroes. You can find the target device under lsblk command.

$ sudo wipefs /dev/[DEVICE]
$ sudo wipefs --all --force /dev/[DEVICE]*
$ sudo dd if=/dev/zero of=/dev/[DEVICE] status=progress bs=32768 count=1

Optionally you can zeroes the whole device:

$ sudo dd if=/dev/zero of=/dev/[DEVICE] status=progress bs=32768 count=$(expr $(lsblk -bno SIZE /dev/[DEVICE] | head -1) \/ 32768)

Flashing the microSD card

Insert the microSD card into your PC, locate its device under lsblk and write the image:

$ cd ~/ox64/openbouffalo/firmware # if you downloaded pre-built images
 # or
$ cd ~/ox64/buildroot/output/images # if you built your own images

$ sudo dd if=sdcard.img of=/dev/[DEVICE] bs=1M status=progress conv=fsync

Booting for the first time

Power off your Ox64 and insert the microSD card.

Open a terminal window to connect to the D0 core’s (i.e. Linux’s) serial console:

$ minicom -b 2000000 -D /dev/ttyACM0

If you are using a Pico or Bluepill as your serial adapter, open another terminal window to to monitor the M0 core’s serial console (reminder: /dev/ttyACM1 is the same port we previously used for flashing):

$ minicom -b 2000000 -D /dev/ttyACM1

Re-apply power to the Ox64.

On the main/D0 console (/dev/ttyACM0) you will see Linux booting up. When prompted, log in as root with no password. In case the SD card is missing or empty, you’ll get a Card did not respond to voltage select! : -110 error.

On the M0 console (/dev/ttyACM1) you’ll see following messages until the sytem is fully loaded:

[I][MBOX] Mailbox IRQ Stats:
[I][MBOX] Peripheral SDH (33): 0
[I][MBOX] Peripheral GPIO (60): 0
[I][MBOX] Unhandled Interupts: 0 Unhandled Signals 0

Once the system is running, the “MBOX” logs will abruptly disappear and you’ll be able to manage the M0 multimedia core, i.e. wifi settings, etc. When prompted, type help to see available commands.

Connecting the Ox64 to your WiFi network

The simplest way to connect is to run the following command from the Linux console (i.e. /dev/ttyACM0):

$ blctl connect_ap <YourSSID> <YourPassword>

Wait for it to connect (if you’re monitoring the M0 console on /dev/ttyACM1 it should tell you when it’s done), then run the following command from the Linux console:

$ udhcpc -i bleth0

Unfortunately the WiFi range leaves something to be desired. When you are performing the procedure above for the first time, move the Ox64 right next to your router. Once you are successfully connected, you can try experimenting with the maximum range.

For more information on using the blctl command, see here.

Appendix

Adding Nuttx RTOS

In this section, we will set up our Ox64 to dual-boot both Linux and the NuttX real-time operating system. For more information see the official documentation.

First, write the normal Linux image to the SD card if you have not done so already. You can find the correct device under lsblk:

$ cd ~/ox64/openbouffalo/firmware # if you downloaded pre-built images
 # or
$ cd ~/ox64/buildroot/output/images # if you built your own images

$ sudo dd if=/sdcard.img of=/dev/[DEVICE] bs=1M conv=fsync status=progress

Run the following command to re-read the partition tables. Re-inserting the SD card works too:

$ sudo blockdev --rereadpt /dev/[DEVICE]

Download the NuttX image:

$ mkdir -p ~/ox64/nuttx
$ cd ~/ox64/nuttx
$ wget -O ImageNuttx https://github.com/lupyuen2/wip-pinephone-nuttx/releases/download/bl808d-1/Image

Mount the boot partition and make the required modifications:

$ sudo mount /dev/[DEVICE]2 /mnt
$ sudo cp ImageNuttx /mnt/
$ sudo tee -a /mnt/extlinux/extlinux.conf <<EOF
 LABEL PINE64 OX64 Nuttx
        KERNEL ../ImageNuttx
        FDT ../bl808-pine64-ox64.dtb
 EOF
$ sudo umount /mnt

Mount the rootfs and make the required modifications:

$ sudo mount /dev/[DEVICE]3 /mnt
$ sudo cp ImageNuttx /mnt/boot/
$ sudo tee -a /mnt/boot/extlinux/extlinux.conf <<EOF
 LABEL PINE64 OX64 Nuttx
        KERNEL ../ImageNuttx
        FDT ../bl808-pine64-ox64.dtb
 EOF
$ sudo umount /mnt

Enjoy your new Nuttx booting option!


Development Efforts


Further information

Compatible UARTs

When the Ox64 is in bootloader mode, some UARTs are unable to communicate with it. When this is the case, utilities such as BLDevCube are unable to actually program the device. If you see “Shake hand fail” and an empty ack, and your device is in bootloader mode, then it is likely an incompatible UART.

The below devices have been tested and verified as working:

  • Raspberry Pi Pico - running the following UART firmware (GP4 and GP5 are used for port 0, GP12 and GP13 for port 1)
  • Compiled binary for Pi Pico and connectivity diagram is here
  • ESP32 with CP210x - bridge the EN pin to ground to disable the ESP32 itself, and then connect the TX on the esp32 to 14 on the Ox64 and RX to pin 15. Note that only baud rate 115200 works, and this doesn’t seem to work for everyone)
  • Stand-alone CP2102 dongle works at 115200 baud. Brand used was HiLetgo.
  • STM32F401 BlackPill - running the Black Magic Debug firmware
  • STM32F103C8T6 BluePill - running Black Magic Debug.
  • STM32F103C8T6 BluePill - running BluePill Serial Monster
  • Some UART adapters based on the FT232H (note that the FT232RL does not work, and neither does the Pine 64 JTAG)
  • Some CH340G based adapters work and some don’t.

Datasheets

Bouffalo BL808 SoC information:

SPI NOR Flash information:

Power Regulator information:

MicroSD socket information:

Resources

Ox64 BL808 RISC-V SBC articles by Lup Yuen LEE:

Git repositories:

Schematics and certifications

Pinout for wiring ethernet PHY to EMAC

  • Baseboard dimensions: 51 mm x 21 mm x 19 mm x 3.5 mm (breadboard-friendly)
  • Input power: 5 V, 0.5 A through the microUSB or USB-C ports

Production version schematic:

Prototype (dispatched to developers) schematic:

Certifications:

  • Not available yet

SoC and Memory Specification

Based on the Bouffalo Lab BL808

CPU Architecture

T-Head C906 480 MHz 64-bit RISC-V CPU:

  • Supports RISC-V RV64IMAFCV instruction architecture
  • Five-stage single-issue sequentially executed pipeline
  • Level-1 instruction and data cache of Harvard architecture, with a size of 32 KB and a cache line of 64B
  • Sv39 memory management unit, realizing the conversion of virtual and real addresses and memory management
  • jTLB that supports 128 entries
  • Supports AXI 4.0 128-bit master interface
  • Supports core local interrupt (CLINT) and platform-level interrupt controller (PLIC)
  • With 80 external interrupt sources, 3 bits for configuring interrupt priority
  • Supports BHT (8K) and BTB
  • Compatible with RISC-V PMP, 8 configurable areas
  • Supports hardware performance monitor (HPM) units
  • See here

T-Head E907 320 MHz 32-bit RISC-V CPU:

  • Supports RISC-V RV32IMAFCP instruction set
  • Supports RISC-V 32-bit/16-bit mixed instruction set
  • Supports RISC-V machine mode and user mode
  • Thirty-two 32-bit integer general purpose registers (GPR) and thirty-two 32-bit/64-bit floating-point GPRs
  • Integer (5-stage)/floating-point (7-stage), single-issue, sequentially executed pipeline
  • Supports AXI 4.0 main device interface and AHB 5.0 peripheral interface
  • 32K instruction cache, two-way set associative structure
  • 16K data cache, two-way set associative structure
  • See here

T-Head E902 150 MHz 32-bit RISC-V CPU:

System Memory

  • Embedded 64MB PSRAM