✅ Check the [User Guide in section 7.2](https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/vir_com_port.html) to find to find out which pins are reserved for these and what their configuration needs to be.
The `nrf52840-hal` is a crate that exports all the `52840` flagged features from the `nrf-hal-common`. Let's take a look at the `nrf52840-hal`'s [Uarte module](https://github.com/nrf-rs/nrf-hal/blob/v0.14.1/nrf-hal-common/src/uarte.rs).
In line 16 we see, that the nRF52840 uses the `hal::pac::UARTE1` peripheral.
In line 44 you find the `struct Uarte<T>(T)`, the interface to a UARTE instance `T`. Besides the instance `T`, the instantiating method takes variables of the following types as arguments: `Pins`, `Parity` and `Baudrate`.
A quick search of the document reveals where to find all of them:
✅ Add `struct Uarte` that serves as a wrapper for underlying HAL UART driver.
The struct has one field labelled `inner` which is of type `hal::Uarte` but with the type parameter `T` being set to `hal::pac::UARTE1`.
The main difference between using our `Uarte` object and the underlying HAL `Uarte` object is that *ours* will be pre-configured for the correct pins and baud rate, according to the layout of our nRF52840-DK board and the Virtual COM Port interface chip on the other end of the UART link.
✅ Take a closer look at the definition of the `uarte::Pins` struct in the `nrf-hal`. Compare the pin type configurations with the ones you have already imported in `lib.rs`. Add the ones you're missing.
✅ Create a Uarte driver with `hal::uarte::Uarte::new(...)` and bind it to a variable called `uarte` - we will stash this in our own `Uarte` struct later.
Creating the Uarte driver requires four arguments:
We want to implement the `fmt::Write` trait so that users can call `write!` on our Uarte object
When implementing this, we can't just write to the `Uarte` instance because a simple write of a string literal would try and read the string literal from flash memory. This does not work because the EasyDMA peripheral in the nRF52 series can only access RAM, not flash.
Instead our implementation must ensure all the strings are copied to a stack allocated buffer and that buffer is passed to the Uarte's `write` method.
✅ To copy all data into an on-stack buffer, *iterate* over *chunks* of the string and copy them into the buffer (noting that the chunk length may be less than the requested size if you are at the end of the input string).