embassy-rs/embassy · error

not implemented

Error message

not implemented

What it means

The DTS (digital temperature sensor) factory_calibration() reads T0VALR1 and maps the encoded reference temperature t0: 0 => 30 °C, 1 => 130 °C; any other encoded value hits an unimplemented!() panic. The library throws it because the register encoding is documented as 2 values and anything else indicates silicon/register surprises. In practice it fires when the DTS calibration block was not programmed (reads 0xFF / reserved values).

Solutions

1. Ensure the DTS peripheral clock is enabled (via RCC) before calling factory_calibration()
2. Verify factory calibration data exists in the calibration area for your exact chip part number
3. Call the runtime calibration path (calibrate / measure with the driver's calibration routine) instead of relying on factory constants
4. If the chip encodes additional t0 values, patch the match arms in embassy-stm32/src/dts/mod.rs

Example fix

// before
let cal = Dts::factory_calibration(); // panics if t0 encoding unexpected
// after
let cal = dts.calibrate(&mut sensor).await; // runtime calibration instead

let t0 = Dts::regs().t0valr1().read().t0();
if t0 > 1 {
    // fall back to runtime calibration
    return None;
}

fn valid_t0_encoding(t0: u8) -> bool {
    matches!(t0, 0 | 1)
}

// panic-based; guard reads first
if !valid_t0_encoding(t0_raw) {
    let cal = runtime_calibration();
}

When it happens

Trigger: Calling Dts::factory_calibration() when T0VALR1.T0 contains a value other than 0 or 1 — typically because DTS calibration data was never written to OTP/system flash, or reading before the DTS/its clock is enabled so the read returns garbage.

Common situations: Using DTS on an STM32 whose factory calibration area is erased or not loaded (custom bootloader, clone/defective chip); forgetting to enable the DTS peripheral clock before reading calibration registers.

Related errors

• DTS PCLK frequency must be less than 127 MHz.
• SYS not supported yet
• AUDIOCLK not supported yet
• invalid burst size
• invalid word size

AI-assisted analysis of embassy-rs/embassy@463a07b963 (2026-09-10). Data as JSON: /api/errors/33692e13f4089299. Report an issue: GitHub.

Appendix: source

Thrown at embassy-stm32/src/dts/mod.rs:128

        Self { _peri }
    }

    /// Reconfigure the driver.
    pub fn set_config(&mut self, config: &Config) {
        Self::regs().cfgr1().modify(|w| {
            w.set_smp_time(config.sample_time as u8);
            w.set_intrig_sel(config.trigger as u8);
        });
    }

    /// Get the read-only factory calibration values used for converting a
    /// measurement to a temperature.
    pub fn factory_calibration() -> FactoryCalibration {
        let t0valr1 = Self::regs().t0valr1().read();
        let t0 = match t0valr1.t0() {
            0 => 30,
            1 => 130,
            _ => unimplemented!(),
        };
        let fmt0 = Hertz::hz(t0valr1.fmt0() as u32 * 100);

        let ramp_coeff = Self::regs().rampvalr().read().ramp_coeff();

        FactoryCalibration { t0, fmt0, ramp_coeff }
    }

    /// Perform an asynchronous temperature measurement. The returned future can
    /// be awaited to obtain the measurement.
    ///
    /// The future returned waits for the next measurement to complete.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use embassy_stm32::{bind_interrupts, dts};
    /// use embassy_stm32::dts::Dts;

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