This is a litte application using Zephyr RTOS on Teensy 4.0 hardware. It aims to test various hardware peripherals and kernel functions. Maybe it can provide a starting point for real world applications.
Every thread has a start delay of 500ms. This ensures that the device is properly listed on the usb host and com port is open before the log output runs in.
This tutorial was tested on Ubuntu 18.04.
sudo apt update
sudo apt upgrade
sudo apt install --no-install-recommends git cmake ninja-build gperf \
ccache dfu-util device-tree-compiler wget \
python3-dev python3-pip python3-setuptools python3-tk python3-wheel xz-utils file \
make gcc gcc-multilib g++-multilib libsdl2-dev putty
wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | sudo apt-key add -
sudo apt-add-repository 'deb https://apt.kitware.com/ubuntu/ bionic main'
sudo apt install cmake=3.17.3-0kitware1 cmake-data=3.17.3-0kitware1
Newer versions of cmake will not work!
pip3 install --user -U west
echo 'export PATH=~/.local/bin:"$PATH"' >> ~/.bashrc
source ~/.bashrc
west init ~/zephyrproject
cd ~/zephyrproject
west update
If you want to use the latest stable version of Zephyr instead of bleeding-edge, execute:
cd zephyr
git checkout v2.4-branch
pip3 install --user -r ~/zephyrproject/zephyr/scripts/requirements.txt
cd ~
wget https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.11.4/zephyr-sdk-0.11.4-setup.run
chmod +x zephyr-sdk-0.11.4-setup.run
./zephyr-sdk-0.11.4-setup.run -- -d ~/zephyr-sdk-0.11.4
sudo cp ~/zephyr-sdk-0.11.4/sysroots/x86_64-pokysdk-linux/usr/share/openocd/contrib/60-openocd.rules /etc/udev/rules.d
sudo udevadm control --reload
cd ~
mkdir repos
cd repos
git clone https://github.com/bdkrae/zephyr.git
cd zephyr
git checkout teensy4-branch
cd ~/zephyrproject/zephyr/boards/arm/
ln -s ~/repos/zephyr/boards/arm/teensy4
cd ~/repos
git clone https://github.com/ufechner7/zephyr_teensy4_test.git
cd zephyr_teensy4_test/
- source the script zephyr-env.sh
source ~/zephyrproject/zephyr/zephyr-env.sh - execute the build script
./build.sh
- check out and compile teensy_loader_cli
cd ~/repos
git clone https://github.com/PaulStoffregen/teensy_loader_cli.git
sudo apt-get install libusb-dev
make
cd /usr/local/bin
sudo ln -s ~/repos/teensy_loader_cli/teensy_loader_cli
- install 49-teensy.rules in /etc/udev/rules.d (download them from http://www.pjrc.com/teensy/49-teensy.rules ) and reboot
Connect Teensy 4.0 via USB. It must blink slowly. Press the button.
Execute the script ./burn.sh
The script automatically launches the terminal program putty after flashing the board, so you can see the output.
Example output
[00:00:00.357,000] <inf> usb_cdc_acm: Device configured
[00:00:00.357,000] <wrn> usb_dc_mcux_ehci: endpoint 0x1 already occupied
[00:00:00.420,000] <inf> sys: Started zephyr 2.4.0 on board teensy40.
[00:00:00.500,000] <inf> uart: Thread started
[00:00:00.500,000] <inf> but: Set up button at GPIO_1 pin 25
[00:00:00.500,000] <inf> led: Thread started
[00:00:00.500,000] <inf> pin: Thread started
[00:00:07.754,000] <dbg> but.button_main_f: Button state is now 1
[00:00:07.786,000] <dbg> but.button_main_f: Button state is now 0
Standard output is mapped to usb according to usb/console example. This is done in main.c. As described there the board will be detected as a CDC_ACM serial device.
Known limitation: In the moment the usb console cannot be used as input device.
The led flashes continously to give an visual indication that application is running. The toggle pin is mapped to teensy pin 9 (Teensy 4.0).
The names and pin numbers used by the Teensy documentation, the schematics/datasheet and by the Zephyr driver are not consistant. Here a table to translate these names:
| GPIO | PIN | Name | Teensy PIN | Remark | Tested |
|---|---|---|---|---|---|
| 1 | 3 | AD_B0_3 | 0 | UART6_RX | OK |
| 1 | 2 | AD_B0_2 | 1 | UART6_TX | OK |
| 4 | 4 | EMC_04 | 2 | OK | |
| 4 | 5 | EMC_05 | 3 | OK | |
| 4 | 6 | EMC_06 | 4 | OK | |
| 4 | 8 | EMC_08 | 5 | OK | |
| 2 | 10 | B0_10 | 6 | OK | |
| 2 | 17 | B1_01 | 7 | UART4_RX | OK |
| 2 | 16 | B1_00 | 8 | UART4_TX | OK |
| 2 | 11 | B0_11 | 9 | OK | |
| 2 | 0 | B0_00 | 10 | CS | OK |
| 2 | 2 | B0_02 | 11 | MOSI | OK |
| 2 | 1 | B0_01 | 12 | MISO | OK |
| 2 | 3 | B0_ | 13 | Onboard LED | OK |
| 1 | 18 | AD_B1_02 | 14 / A0 | OK | |
| 1 | 19 | AD_B1_03 | 15 / A1 | OK | |
| 1 | 23 | AD_B1_07 | 16 / A2 | OK | |
| 1 | 22 | AD_B1_06 | 17 / A3 | OK | |
| 1 | 17 | AD_B1_01 | 18 / A4 | OK | |
| 1 | 16 | AD_B1_00 | 19 / A5 | OK | |
| 1 | 26 | AD_B1_10 | 20 / A6 | UART8_TX | OK |
| 1 | 27 | AD_B1_11 | 21 / A7 | UART8_RX | OK |
| 1 | 24 | AD_B1_08 | 22 / A8 | OK | |
| 1 | 25 | AD_B1_09 | 23 / A9 | OK | |
| 1 | 12 | AD_B0_12 | 24 / A10 | Backside | OK |
| 1 | 13 | AD_B0_13 | 25 / A11 | Backside | |
| 1 | 30 | AD_B1_14 | 26 / A12 | Backside | OK |
| 1 | 31 | AD_B1_15 | 27 / A13 | Backside | |
| 3 | 18 | EMC_32 | 28 | Backside | OK |
| 4 | 31 | EMC_31 | 29 | Backside | |
| 3 | 23 | EMC_37 | 30 | Backside | OK |
| 3 | 22 | EMC_36 | 31 | Backside | |
| 2 | 12 | B0_12 | 32 | Backside | OK |
| 4 | 7 | EMC_07 | 33 | Backside |
Example
Add the following lines to teensy40.overlay to access Teensy pin 9 under the name toggle_gpio:
toggle_gpio: toggle-gpio {
gpios = <&gpio2 11 GPIO_ACTIVE_HIGH>;
label = "Toggle Teensy Pin 9";
};
You can find the GPIO number and PIN number in the table above.
On every edge the button pushes a string to a message queue which is then processed by the uart. Pushputton is mapped to teensy pin 23. An external pullup resistor must be used currently.
The uart always listens for incoming data and dumps it to the log. It also listens for data in the message queue, which are sent out immediately. Used uart is mapped to teens pins 7/8 (Rx2/TX2 in teensy numbering, lpuart4 in nxp numbering). Rx/Tx shorted externally. If pin 7 and 8 are connected and you press the button, you see the data that the UART received as follows:
[00:06:32.588,000] <dbg> but.button_main_f: Button state is now 1
[00:06:32.590,000] <dbg> uart: Received data:
0a 42 75 74 74 6f 6e 20 73 74 61 74 65 20 69 73 |.Button state is
20 31 0d | 1.
[00:06:33.914,000] <dbg> but.button_main_f: Button state is now 0
[00:06:33.916,000] <dbg> uart: Received data:
0a 42 75 74 74 6f 6e 20 73 74 61 74 65 20 69 73 |.Button state is
20 30 0d | 0.
Visual Studio Code works great and has good plugins for syntax highlighting, goto-definition, previewing and more. Suggested plugins:
- C/C++
- Python
- DeviceTree for Zephyr Project
- RST Preview
See: https://code.visualstudio.com/download
If you want to learn more, continue reading at: https://github.com/ufechner7/teensy4_shell
In case you have problems to run the above mentioned examples, please create an issue in this repository.
Uwe Fechner