The template `down-the-stack/dk_bsc/src/lib.rs` already contains the LED and Timer implementations.
You can test after each step by running the following command out of `down-the-stack/apps`
```
cargo run --bin hello
```
This program will not call any of the functions you are implementing, so it does not matter if they are incomplete. It will refuse to build if there are errors present in the lib!
Note for trainer: Introduction to the exercise is a guided tour through the template, and it's architecture. Make the participants aware of the placeholders for their implementations. run the hello example on the unmodified lib.
The boards peripherals are represented as nested structs. The `struct Board` contains fields that represent single peripherals or groups of peripherals as structs, which in turn either contain a field of the single peripheral or ...
You have to add structs to represent the buttons and the UARTE peripheral to the board struct.
Go to [Nordic Infocenter](https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/intro.html) to download the User Guide. You can find all the information that is relevant to this exercise in there.