# Timers and Time

Next we'll look into the time related APIs exposed by the `dk` HAL.

Open the `src/bin/blinky.rs` file.

This program will blink (turn on and off) one of the LEDs on the board. The time interval between each toggle operation is one second. This wait time between consecutive operations is generated by the blocking `timer.wait` operation. This function call will block the program execution for the specified [`Duration`] argument.

[`Duration`]: https://doc.rust-lang.org/core/time/struct.Duration.html

The other time related API exposed by the `dk` HAL is the `dk::uptime` function. This function returns the time that has elapsed since the call to the `dk::init` function. This function is used in the program to log the time of each LED toggle operation.

Next, we'll look into the radio API exposed by the `dk` HAL. But before that we'll need to set up the nRF52840 Dongle.

[❗️assignment to chnge something]