Wrapper for RTC Slow memory

[weiying-chen]

Is there a wrapper for this?

RTC Slow Memory

Global and static variables used by code which runs from RTC memory must be placed into RTC Slow memory. For example deep sleep variables can be placed here instead of RTC FAST memory, or code and variables accessed by the ULP Coprocessor Programming.

The attribute macro named RTC_NOINIT_ATTR can be used to place data into this type of memory. The values placed into this section keep their value after waking from deep sleep.

I searched all over Github, but I couldn't find anything.

[Vollbrecht]

You don't need any wrapper for it since you can directly specify where you want stuff to be linked.

Here is a small example

#[no_mangle]
#[link_section = ".rtc.data"]
static mut RTC_VARIABLE: u32 = 0;

fn main() {
    // It is necessary to call this function once. Otherwise some patches to the runtime
    // implemented by esp-idf-sys might not link properly. See https://github.com/esp-rs/esp-idf-template/issues/71
    esp_idf_svc::sys::link_patches();

    // Bind the log crate to the ESP Logging facilities
    esp_idf_svc::log::EspLogger::initialize_default();

    log::info!("Current RTC Value!: {}", unsafe { RTC_VARIABLE });
    unsafe { RTC_VARIABLE += 1 };

    FreeRtos::delay_ms(2_000);
    unsafe {
        esp_deep_sleep(2_000_000);
    }
}

Keep in mind that this example only illustrate the point. Please use something more appropriate that a static mut raw pointer here as its an easy footgun

[weiying-chen]

Thanks for the reply!