esp_hal/analog/adc/calibration/
basic.rs

1use core::marker::PhantomData;
2
3use crate::analog::adc::{
4    AdcCalEfuse,
5    AdcCalScheme,
6    AdcCalSource,
7    AdcConfig,
8    Attenuation,
9    CalibrationAccess,
10};
11
12/// Basic ADC calibration scheme
13///
14/// Basic calibration sets the initial ADC bias value so that a zero voltage
15/// gives a reading of zero. The correct bias value is usually stored in efuse,
16/// but can also be measured at runtime by connecting the ADC input to ground
17/// internally.
18///
19/// Failing to apply basic calibration can substantially reduce the ADC's output
20/// range because bias correction is done *before* the ADC's output is truncated
21/// to 12 bits.
22#[derive(Clone, Copy)]
23pub struct AdcCalBasic<ADCX> {
24    /// Calibration value to set to ADC unit
25    cal_val: u16,
26
27    #[cfg(any(esp32c5, esp32c6, esp32c61, esp32h2))]
28    chan_compens: i32,
29
30    _phantom: PhantomData<ADCX>,
31}
32
33impl<ADCX> crate::private::Sealed for AdcCalBasic<ADCX> {}
34
35impl<ADCX> AdcCalScheme<ADCX> for AdcCalBasic<ADCX>
36where
37    ADCX: AdcCalEfuse + CalibrationAccess,
38{
39    fn new_cal(atten: Attenuation) -> Self {
40        Self::new_cal_with_channel(atten, 0)
41    }
42
43    fn new_cal_with_channel(atten: Attenuation, _channel: u8) -> Self {
44        // Try to get init code (Dout0) from efuse
45        // Dout0 means mean raw ADC value when zero voltage applied to input.
46        let cal_val = ADCX::init_code(atten).unwrap_or_else(|| {
47            // As a fallback try to calibrate via connecting input to ground internally.
48            AdcConfig::<ADCX>::adc_calibrate(atten, AdcCalSource::Gnd)
49        });
50
51        #[cfg(any(esp32c5, esp32c6, esp32c61, esp32h2))]
52        let chan_compens = ADCX::cal_chan_compens(atten, _channel).unwrap_or(0);
53
54        Self {
55            cal_val,
56            #[cfg(any(esp32c5, esp32c6, esp32c61, esp32h2))]
57            chan_compens,
58            _phantom: PhantomData,
59        }
60    }
61
62    fn adc_cal(&self) -> u16 {
63        self.cal_val
64    }
65
66    #[cfg(any(esp32c5, esp32c6, esp32c61, esp32h2))]
67    fn adc_val(&self, val: u16) -> u16 {
68        (val as i32 - self.chan_compens).clamp(0, ADCX::ADC_VAL_MASK as i32) as u16
69    }
70}
esp_hal/analog/adc/calibration/basic.rs

esp_hal/analog/adc/calibration/
basic.rs
