PAC Exercise

In this exercise you will generate a PAC (Peripheral Access Crate) from an svd file, and write a small program that enables the UARTE0 register.

In this exercise you will learn how to

Generate a Peripheral Access Crate from an svd file
Two ways to write into a register to enable and disable it

Prerequisites

[todo!]

Tasks

Generating the PAC

✅ Install svd2rust using the following command:

cargo install svd2rust

✅ Download https://github.com/NordicSemiconductor/nrfx/blob/master/mdk/nrf52.svd (This version has an error: writeonce needs to be changed to writeOnce) Place the file into down-the-stack/dk-pac. Note how we provide a Cargo.toml file, as it will not be generated by svd2rust.

✅ In the terminal, go to the file's location. Run svd2rust with the SVD file to generate a PAC using the cortex-m flag.

svd2rust --target cortex-m -i nrf52.svd

If you check the folder down-the-stack/dk-pac now, you see three new files:

lib.rs - the file that contains the generated code for the pac
device.x - linker sections(?)
build.rs - linker script

✅ Open the generated lib.rs with an editor. Notice how it's one long line of text in the source file.

✅ Look at the PAC docs with cargo doc --open.

✅ cargo fmt the crate. No change to the docs, but a bit more readable.

✅ Install form with the following command:

cargo install form

✅ use form to process the one-big-file into one-file-per-module with the following command:

form -i src/lib.rs -o src/


✅  Re-run `cargo fmt`. 


## Enabling the UARTE0 peripheral



Write a simple program which uses the PAC to enable the UART. See how writing arbitrary values to the ENABLE field in the ENABLE register is unsafe, because only values 0 or 8 should be used.

✅ Finding your way through the PAC

find the "board" struct in docs und take()

take() assures, that only one instance of this can exist. hence, it's safe. 

Find the definition of the ENABLE register for UARTE0, in the PDF datasheet and in the SVD file, and in the svd2rust generated code.

✅ uarte0.rs/enable

read().bits
write(closure)



✅ Import the PAC

cargo.toml

dk_pac = { path = "../dk_pac", features = ["critical-section"]}

uarte_enable.rs

```rust 
use dk_pac::UARTE0;

✅ Take ownership of the peripherals with take() and bind the UARTE0 peripheral to it's own variable

✅ Write a helper function that prints the status of the uarte peripheral. Check if the enable is not 0

base address Uarte0 0x40002000 enable UARTE 0x500 ✅ Enable the peripheral ✅ Disable the peropheral with an unsafe write

2.6 KiB Raw Blame History

PAC Exercise

In this exercise you will learn how to

Prerequisites

Tasks

Generating the PAC

2.6 KiB

Raw Blame History