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Compile and install the Tock kernel

To start with Jazda, first build the Tock kernel. Check out our Tock repository using git. Read the readme for the SMA Q3 board: boards/nordic/sma_q3/

Compile and install an example application

Once you have flashed it, try building an example application. Use git to check out the Tock userspace. Let's try to build an example.

Go to the libtock-rs directory and issue those commands:

cargo install elf2tab
EXAMPLE=leds make nrf52840

This will produce a file suitable for flashing. Look in the directory ../libtock-rs/target/thumbv7em-none-eabi/release/examples/. The file is we're looking for is called

To install the application, use tockloader again:

tockloader install ../libtock-rs/target/thumbv7em-none-eabi/release/examples/ --board sma_q3 --openocd
tockloader listen --board sma_q3 --openocd --rtt

The listen command will start the newly flashed firmware and present its output.

Compile and install jazda apps

Check out the core repository. To build the map and the speed applications use one of the below commands:

just build_bin map
just build_bin speed

To flash either of the apps, you would issue:

tockloader install target/thumbv7em-none-eabi/release/ --board sma_q3 --openocd
tockloader install target/thumbv7em-none-eabi/release/ --board sma_q3 --openocd

Currently only a single app can be flashed to the watch at the same time. Use the below commands to display and delete already installed apps:

tockloader list --board sma_q3 --openocd
tockloader uninstall --board sma_q3 --openocd

Start and Stop applications

If you issue just listen in the core directory (which is a shorthand for tockloader listen --board sma_q3 --openocd --rtt) while the watch is connected, you will reset the watch, autostart the active app on the watch. If you want to keep it running, just disconnect the watch while listening. In order to stop the app, interrupt the listening process with CTRL-C and the application will not run any longer.

This is how it is supposed to look like

jazda on a bike, speed app showing 0 km/h