= Getting started

So you want to try Embassy, great! To get started, there are a few tools you need to install:

* link:https://rustup.rs/[rustup] - the Rust toolchain is needed to compile Rust code.
* link:https://probe.rs/[probe-rs] - to flash the firmware on your device. If you already have other tools like `OpenOCD` setup, you can use that as well.

If you don't have any supported board, don't worry: you can also run embassy on your PC using the `std` examples.

== Getting a board with examples

Embassy supports many microcontroller families, but the quickest way to get started is by using a board which Embassy has existing example code for.

This list is non-exhaustive. If your board isn’t included here, check the link:https://github.com/embassy-rs/embassy/tree/main/examples[examples folder] to see if example code has been written for it.

=== nRF kits

* link:https://www.nordicsemi.com/Products/Development-hardware/nrf52-dk[nRF52 DK]
* link:https://www.nordicsemi.com/Products/Development-hardware/nRF9160-DK[nRF9160 DK]

=== STM32 kits

* link:https://www.st.com/en/evaluation-tools/nucleo-h743zi.html[STM32 Nucleo-144 development board with STM32H743ZI MCU]
* link:https://www.st.com/en/evaluation-tools/nucleo-f429zi.html[STM32 Nucleo-144 development board with STM32F429ZI MCU]
* link:https://www.st.com/en/evaluation-tools/b-l4s5i-iot01a.html[STM32L4+ Discovery kit IoT node, low-power wireless, BLE, NFC, WiFi]
* link:https://www.st.com/en/evaluation-tools/b-l072z-lrwan1.html[STM32L0 Discovery kit LoRa, Sigfox, low-power wireless]
* link:https://www.st.com/en/evaluation-tools/nucleo-wl55jc.html[STM32 Nucleo-64 development board with STM32WL55JCI MCU]
* link:https://www.st.com/en/evaluation-tools/b-u585i-iot02a.html[Discovery kit for IoT node with STM32U5 series]


=== RP2040 kits

* link:https://www.raspberrypi.com/products/raspberry-pi-pico/[Raspberry Pi Pico]

=== ESP32

* link:https://github.com/esp-rs/esp-rust-board[ESP32C3]

== Running an example

First you need to clone the link:https://github.com/embassy-rs/embassy[github repository];

[source, bash]
----
git clone https://github.com/embassy-rs/embassy.git
cd embassy
----

Once you have a copy of the repository, find examples folder for your board and, and build an example program. `blinky` is a good choice as all it does is blink an LED – the embedded world’s equivalent of “Hello World”.

[source, bash]
----
cd examples/nrf52840
cargo build --bin blinky --release
----

Once you’ve confirmed you can build the example, connect your computer to your board with a debug probe and run it on hardware:

[source, bash]
----
cargo run --bin blinky --release
----

If everything worked correctly, you should see a blinking LED on your board, and debug output similar to this on your computer:

[source]
----
    Finished dev [unoptimized + debuginfo] target(s) in 1m 56s
     Running `probe-run --chip STM32F407VGTx target/thumbv7em-none-eabi/debug/blinky`
(HOST) INFO  flashing program (71.36 KiB)
(HOST) INFO  success!
────────────────────────────────────────────────────────────────────────────────
0 INFO  Hello World!
└─ blinky::__embassy_main::task::{generator#0} @ src/bin/blinky.rs:18
1 INFO  high
└─ blinky::__embassy_main::task::{generator#0} @ src/bin/blinky.rs:23
2 INFO  low
└─ blinky::__embassy_main::task::{generator#0} @ src/bin/blinky.rs:27
3 INFO  high
└─ blinky::__embassy_main::task::{generator#0} @ src/bin/blinky.rs:23
4 INFO  low
└─ blinky::__embassy_main::task::{generator#0} @ src/bin/blinky.rs:27
----

NOTE: How does the `+cargo run+` command know how to connect to our board and program it? In each `examples` folder, there’s a `.cargo/config.toml` file which tells cargo to use link:https://probe.rs/[probe-rs] as the runner for ARM binaries in that folder. probe-rs handles communication with the debug probe and MCU. In order for this to work, probe-rs needs to know which chip it’s programming, so you’ll have to edit this file if you want to run examples on other chips.

=== It didn’t work!

If you hare having issues when running `+cargo run --release+`, please check the following:

* You are specifying the correct `+--chip+` on the command line, OR
* You have set `+.cargo/config.toml+`’s run line to the correct chip, AND
* You have changed `+examples/Cargo.toml+`’s HAL (e.g. embassy-stm32) dependency's feature to use the correct chip (replace the existing stm32xxxx feature)

At this point the project should run. If you do not see a blinky LED for blinky, for example, be sure to check the code is toggling your board's LED pin.

If you are trying to run an example with `+cargo run --release+` and you see the following output:
[source]
----
0.000000 INFO Hello World!
└─ <invalid location: defmt frame-index: 14>
0.000000 DEBUG rcc: Clocks { sys: Hertz(80000000), apb1: Hertz(80000000), apb1_tim: Hertz(80000000), apb2: Hertz(80000000), apb2_tim: Hertz(80000000), ahb1: Hertz(80000000), ahb2: Hertz(80000000), ahb3: Hertz(80000000) }
└─ <invalid location: defmt frame-index: 124>
0.000061 TRACE allocating type=Interrupt mps=8 interval_ms=255, dir=In
└─ <invalid location: defmt frame-index: 68>
0.000091 TRACE   index=1
└─ <invalid location: defmt frame-index: 72>
----

To get rid of the frame-index error add the following to your `Cargo.toml`:

[source,toml]
----
[profile.release]
debug = 2
----

If you’re get an extremely long error message containing something like the following:

[source]
----
error[E0463]: can't find crate for `std`
  |
  = note: the `thumbv6m-none-eabi` target may not support the standard library
  = note: `std` is required by `stable_deref_trait` because it does not declare `#![no_std]`
----

Make sure that you didn’t accidentally run `+cargo add probe-rs+` (which adds it as a dependency) instead of link:https://probe.rs/docs/getting-started/installation/[correctly installing probe-rs].

If you’re using a raspberry pi pico-w, make sure you’re running `+cargo run --bin wifi_blinky --release+` rather than the regular blinky. The pico-w’s on-board LED is connected to the WiFi chip, which needs to be initialized before the LED can be blinked.

If you’re still having problems, check the link:https://embassy.dev/book/dev/faq.html[FAQ], or ask for help in the link:https://matrix.to/#/#embassy-rs:matrix.org[Embassy Chat Room].

== What's next?

Congratulations, you have your first Embassy application running! Here are some suggestions for where to go from here:

* Read more about the xref:runtime.adoc[executor].
* Read more about the xref:hal.adoc[HAL].
* Start xref:basic_application.adoc[writing your application].
