To those wanting to check the battery level on their 3DS

[LexiBigCheese]

pub struct Mcuhwc(());

impl Mcuhwc {
    pub fn new() -> ctru::Result<Mcuhwc> {
        unsafe {
            ctru::error::ResultCode(ctru_sys::mcuHwcInit())?;
            Ok(Mcuhwc(()))
        }
    }
    pub fn batt(&self) -> u8 {
        let mut out = 0u8;
        unsafe {
            let _ = ctru_sys::MCUHWC_GetBatteryLevel(&mut out);
        }
        out
    }
}

impl Drop for Mcuhwc {
    fn drop(&mut self) {
        unsafe {
            ctru_sys::mcuHwcExit();
        }
    }
}

I don't know what the values are between, but I'm pretty sure you can treat it as a percentage (as in, 88u8 is 88% battery)
There's also a function in ctru_sys to get the Charging State, but you can implement that yourself, right? I believe in you, programmer!