HIGHLY WORK-IN-PROGRESS, CODE NOT COMPLETELY WORKING YET AND MAY NOT BUILD.
Lego Mindstorms NXT2 (ARM7-TDMI, AT91SAM7S, 64 kB RAM, bare-metal) C/C++ FW communicating with Raspberry Pi Zero 2 W (ARM Cortex-A53, 512 MB RAM, Cortex-A53, Debian Linux 10/11) C++/Python SW.
Unfortunately I only have Lego NXT2s and don't want to buy a new EV3 set (the NXT2 was phased out several years ago). However, ARM low-level programming is more fun for me. So I experiment with own bare-metal firmware on the NXT (for sensor/actuator servicing) and control software on the Raspberry Pi (for the algorithms).
Long-term goal: Raspberry Pi4 (or: Pi 3, Pi Zero 2 W) solving a Rubik's cube via Python/OpenCV and then controlling the NXT to physically solve it.
The FW is partly inspired by the LeJos project (especially the AVR support code and the I2C driver code initially based on the code from there).
TODO License?
I'm using Ubuntu 20 as development platform and a RasPi Zero 2 W (or RasPi 3B) as the computer controlling the NXT2.
The embedded cross-build environment can be caught via Docker image below.
Install host build environment
sudo apt install git cmake gcc g++ gdb-multiarch
Install required libraries
sudo apt install python3-dev
sudo apt install python3-pybind11
sudo apt install libncurses5-dev
sudo apt install libusb-1.0-0-dev
Install required libraries
sudo apt install python3
sudo apt install libusb-1.0-0
Run install:
sudo apt install docker.io
Setup privileges for socket:
sudo usermod -aG docker $USER
Run setup script:
cd docker/nxt-build
./setup.sh
Run the container:
docker run --name rpi-nxt2 -it -v <root>/rpi-nxt2:/home/rpi-nxt2 ubuntu20-gcc-arm-none-eabi:latest
To re-run after exit:
docker start rpi-nxt2 -i
Run (in container):
cd /home/rpi-nxt2
scripts/build_nxt.sh <build_type> <app_name>
Run:
cd /home/rpi-nxt2
scripts/build_linux.sh <build_type>
SAM-BA is a flash programmer formerly developed by Atmel (from where the AT91S silicon was originally coming).
The SAM-BA flash programmer can be downloaded from MICROCHIP: https://www.microchip.com/en-us/development-tool/SAM-BA-IN-SYSTEM-PROGRAMMER#
Unpack it and set a soft-link for sam-ba_64:
sudo ln -s /opt/atmel/sam-ba/sam-ba_64 /usr/local/bin/sam-ba
Bring the NXT into flash mode and connect it to USB or JTAG, then:
ice/sam-ba.sh
To start the NXT, just insert the batteries, and it will boot. You should see the title according to your selected
application (see <app_name> above).
There is only the USB connection monitoring console tool available yet:
build/linux/nxt_console/nxt_console
You need to apply the USB permissions rules in the config/udev/rules.d directory to get it running.
For debugging on the NXT I use the SEGGER J-Link ICE (EDU version). For that I soldered pins of the NXT board to expose the JTAG interface. Via adapter, I then connect the ICE to the NXT.
The Debian package can be downloaded from SEGGER: https://www.segger.com/downloads/jlink.
Set soft-link for JLinkGDBServerCLExe:
sudo ln -s /opt/segger/jlink/JLinkGDBServerCLExe /usr/local/bin/jlink-gdbserver
Connect the JTAG connector to the J-Link ICE and run:
tools/jlink_gdbserver.sh
This is tools specific. I use CLion which controls the GDB. Use the host-stools GDB script tools/gdb/host_init.gdb.
This is a trivial process and well-documented for your tools.
See linux/examples/python/hello_world.
See linux/examples/python/nxt_console.
See linux/examples/python/cube_solver.
