Adding support for Nordic nRF52833

[blueluna]

This PR adds support for the Nordic nRF52833. This chip is similar to the nRF52840 with less flash and memory, no CryptoCell, some radio differences and probably som other smaller differences.

I have tested using clocks, gpio, timer and uarte in a RTFM program running on a Nordic nRF52833-DK.

[jonas-schievink]

Great! We're approaching #[cfg]-hell though, maybe we should rethink how we handle different chips...

[fmckeogh]

Is there a good pattern for solving #[cfg] hell?

[jonas-schievink]

I could imagine using a build.rs script to set various cfgs based on the enabled features. Other than that and cfg_if, I don't think there are any good solutions.

[Yatekii]

When you're talking about cfg-hell you mean from a developer perspective, right? Because from a user perspective I like it quite much :)

[blueluna]

With regards to cfg-hell. I experimented a bit with adding a build.rs that generated features from the features defined in Cargo.toml. I am on the fence on if the result is better or not. Maybe open a issue for cfg opportunity for improvement?

impl Instance for SPIM0 {}

#[cfg(feature = "peripheral_spim1_enable")]
impl Instance for SPIM1 {}

#[cfg(feature = "peripheral_spim2_enable")]
impl Instance for SPIM2 {}

#[cfg(feature = "peripheral_spim3_enable")]
impl Instance for SPIM3 {}

build.rs

use std::env;

fn is_feature_enabled(name: &str) -> bool {
    match env::var(format!("CARGO_FEATURE_{}", name.to_uppercase())) {
        Ok(val) => {
            if val == "1" {
                true
            } else {
                false
            }
        }
        Err(_) => false,
    }
}

fn get_chip_code() -> u32 {
    if is_feature_enabled("51") {
        51
    } else if is_feature_enabled("52810") {
        52810
    } else if is_feature_enabled("52811") {
        52811
    } else if is_feature_enabled("52820") {
        52820
    } else if is_feature_enabled("52832") {
        52832
    } else if is_feature_enabled("52833") {
        52833
    } else if is_feature_enabled("52840") {
        52840
    } else if is_feature_enabled("5340") {
        5340
    } else if is_feature_enabled("9160") {
        9160
    } else {
        0
    }
}

fn spim_count(chip_code: u32) -> u32 {
    match chip_code {
        52833 | 52840 => 4,
        52832 => 3,
        _ => 1,
    }
}

fn emit_feature(value: &str) {
    println!("cargo:rustc-cfg=feature=\"{}\"", value);
}

fn main() {
    let chip_code = get_chip_code();
    for n in 0..spim_count(chip_code) {
        emit_feature(&format!("peripheral_spim{}_enable", n));
    }
}

[jonas-schievink]

PR looks good to me, thanks!