update PAC library

va416xx/README.md

@@ -21,9 +21,39 @@ features = ["rt"]
 
 The `rt` feature is optional and recommended. It brings in support for `cortex-m-rt`.
 
-For full details on the autgenerated API, please see the
-[svd2rust documentation](https://docs.rs/svd2rust/0.19.0/svd2rust/#peripheral-api).
+For full details on the autgenerated API, you can read the
+[svd2rust documentation](https://docs.rs/svd2rust/latest/svd2rust/).
 
 ## Regenerating the PAC
 
-You can regenerate the PAC by running the `gen-helper.sh` helper script.
+If you want to re-generate the PAC, for example if the register file `va416xx.svd` changes
+or the `svd2rust` version is updated, you can do some using the following these steps:
+
+1. Make sure all necessary tools are installed: [`svd2rust`](https://docs.rs/svd2rust/latest/svd2rust/),
+   [`svdtools`](https://github.com/rust-embedded/svdtools) and [`form`](https://crates.io/crates/form).
+   You can install all tools with `cargo`:
+
+   ```sh
+   cargo install --locked svd2rust svdtools form
+   ```
+
+2. Patch the vendor-provided SVD file `svd/va41xx.svd`. This can be done using `svdtools` in
+   conjunction with the `svd/va416xx-patch.yml` file.
+
+   ```sh
+   svdtools patch svd/va416xx-patch.yml
+   ```
+
+3. Use `svd2rust` to generate the Rust library
+
+   ```sh
+   svd2rust -i svd/va416xx.svd.patched
+   ```
+
+4. Use the `form` tool to split the generated `lib.rs` into individual modules.
+
+    ```sh
+    form -i lib.rs -o src/
+    ```
+
+The `gen-helper.sh` automates steps 2-4.