Feature esp32s2 adccal

esp-hal/src/analog/adc/calibration/line.rs

@@ -45,6 +45,9 @@ pub struct AdcCalLine<ADCI> {
     /// number with 16 fractional bits.
     gain: u32,
 
+    #[cfg(esp32s2)]
+    offset: i32,
+
     _phantom: PhantomData<ADCI>,
 }
 
@@ -63,7 +66,7 @@ where
             .map(|code| (code, ADCI::cal_mv(atten)))
             .unwrap_or_else(|| {
                 // As a fallback try to calibrate using reference voltage source.
-                // This method is not too good because actual reference voltage may varies
+                // This method is not too good because actual reference voltage varies
                 // in range 1000..=1200 mV and this value currently cannot be read from efuse.
                 (
                     AdcConfig::<ADCI>::adc_calibrate(atten, AdcCalSource::Ref),
@@ -82,6 +85,8 @@ where
         Self {
             basic,
             gain,
+            #[cfg(esp32s2)]
+            offset: ADCI::coeff_b(atten).unwrap_or(0),
             _phantom: PhantomData,
         }
     }
@@ -93,12 +98,17 @@ where
     fn adc_val(&self, val: u16) -> u16 {
         let val = self.basic.adc_val(val);
 
-        (val as u32 * self.gain / GAIN_SCALE) as u16
+        let transformed = val as u32 * self.gain / GAIN_SCALE;
+
+        #[cfg(esp32s2)]
+        let transformed = { i32::max(transformed as i32 + self.offset, 0) };
+
+        transformed as u16
     }
 }
 
-#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s3))]
+#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s2, esp32s3))]
 impl AdcHasLineCal for crate::peripherals::ADC1<'_> {}
 
-#[cfg(any(esp32c3, esp32s3))]
+#[cfg(any(esp32c3, esp32s2, esp32s3))]
 impl AdcHasLineCal for crate::peripherals::ADC2<'_> {}

esp-hal/src/analog/adc/calibration/mod.rs

@@ -1,13 +1,13 @@
-#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s3))]
+#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s2, esp32s3))]
 pub use self::basic::AdcCalBasic;
 #[cfg(any(esp32c3, esp32c6, esp32h2, esp32s3))]
 pub use self::curve::{AdcCalCurve, AdcHasCurveCal};
-#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s3))]
+#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s2, esp32s3))]
 pub use self::line::{AdcCalLine, AdcHasLineCal};
 
-#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s3))]
+#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s2, esp32s3))]
 mod basic;
 #[cfg(any(esp32c3, esp32c6, esp32h2, esp32s3))]
 mod curve;
-#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s3))]
+#[cfg(any(esp32c2, esp32c3, esp32c6, esp32h2, esp32s2, esp32s3))]
 mod line;

esp-hal/src/analog/adc/mod.rs

@@ -225,7 +225,7 @@ impl<ADCI> AdcCalScheme<ADCI> for () {
 }
 
 /// A helper trait to get access to ADC calibration efuses.
-#[cfg(not(any(esp32, esp32s2)))]
+#[cfg(not(any(esp32, esp32h2)))]
 trait AdcCalEfuse {
     /// Get ADC calibration init code
     ///
@@ -241,6 +241,11 @@ trait AdcCalEfuse {
     ///
     /// Returns digital value for reference voltage for a given attenuation
     fn cal_code(atten: Attenuation) -> Option<u16>;
+
+    #[cfg(esp32s2)]
+    /// Get the coeff_b from efuse.
+    /// Use in the equation: millivolts = coeff_a*adc + coeff_b
+    fn coeff_b(atten: Attenuation) -> Option<i32>;
 }
 
 macro_rules! impl_adc_interface {

esp-hal/src/analog/adc/xtensa.rs

@@ -1,9 +1,9 @@
 use core::marker::PhantomData;
 
-#[cfg(esp32s3)]
+#[cfg(any(esp32s2, esp32s3))]
 pub use self::calibration::*;
 use super::{AdcCalScheme, AdcCalSource, AdcChannel, AdcConfig, AdcPin, Attenuation};
-#[cfg(esp32s3)]
+#[cfg(any(esp32s2, esp32s3))]
 use crate::efuse::Efuse;
 use crate::{
     peripherals::{APB_SARADC, SENS},
@@ -16,10 +16,10 @@ mod calibration;
 pub(super) const NUM_ATTENS: usize = 10;
 
 cfg_if::cfg_if! {
-    if #[cfg(esp32s3)] {
+    if #[cfg(any(esp32s2, esp32s3))] {
         const ADC_VAL_MASK: u16 = 0xfff;
         const ADC_CAL_CNT_MAX: u16 = 32;
-        const ADC_CAL_CHANNEL: u16 = 15;
+        const ADC_CAL_CHANNEL: u16 = 0;
     }
 }
 
@@ -61,7 +61,7 @@ where
             // Trigger ADC sampling
             ADCI::start_sample();
 
-            // Wait until ADC1 sampling is done
+            // Wait until ADCI sampling is done
             while !ADCI::is_done() {}
 
             let adc = ADCI::read_data() & ADCI::ADC_VAL_MASK;
@@ -193,14 +193,16 @@ impl RegisterAccess for crate::peripherals::ADC1<'_> {
     }
 }
 
-#[cfg(esp32s3)]
+#[cfg(any(esp32s2, esp32s3))]
 impl super::CalibrationAccess for crate::peripherals::ADC1<'_> {
     const ADC_CAL_CNT_MAX: u16 = ADC_CAL_CNT_MAX;
     const ADC_CAL_CHANNEL: u16 = ADC_CAL_CHANNEL;
     const ADC_VAL_MASK: u16 = ADC_VAL_MASK;
 
     fn enable_vdef(enable: bool) {
-        regi2c::ADC_SAR1_DREF.write_field(enable as u8);
+        // For enable value 4, see <https://github.com/espressif/esp-idf/blob/a25e7ab59ed197817d4a78e139220b2707481f67/components/hal/esp32s3/include/hal/adc_ll.h#L812>
+        // For disable value 1, see <https://github.com/espressif/esp-idf/blob/a25e7ab59ed197817d4a78e139220b2707481f67/components/bootloader_support/src/bootloader_random_esp32s2.c#L81>
+        regi2c::ADC_SAR1_DREF.write_field(if enable { 4 } else { 1 });
     }
 
     fn connect_cal(source: AdcCalSource, enable: bool) {
@@ -296,14 +298,14 @@ impl RegisterAccess for crate::peripherals::ADC2<'_> {
     }
 }
 
-#[cfg(esp32s3)]
+#[cfg(any(esp32s2, esp32s3))]
 impl super::CalibrationAccess for crate::peripherals::ADC2<'_> {
     const ADC_CAL_CNT_MAX: u16 = ADC_CAL_CNT_MAX;
     const ADC_CAL_CHANNEL: u16 = ADC_CAL_CHANNEL;
     const ADC_VAL_MASK: u16 = ADC_VAL_MASK;
 
     fn enable_vdef(enable: bool) {
-        regi2c::ADC_SAR2_DREF.write_field(enable as u8);
+        regi2c::ADC_SAR2_DREF.write_field(if enable { 4 } else { 1 });
     }
 
     fn connect_cal(source: AdcCalSource, enable: bool) {
@@ -395,6 +397,8 @@ where
             .sar_amp_ctrl2()
             .modify(|_, w| unsafe { w.sar_amp_wait3().bits(1) });
 
+        // TODO: ADC2 arbiter: https://github.com/espressif/esp-idf/blob/84df38aab927d50f7ee22d34516d7263f3e96068/components/hal/adc_oneshot_hal.c#L92
+
         Adc {
             _adc: adc_instance,
             active_channel: None,
@@ -489,7 +493,7 @@ where
     }
 }
 
-#[cfg(esp32s3)]
+#[cfg(any(esp32s2, esp32s3))]
 impl super::AdcCalEfuse for crate::peripherals::ADC1<'_> {
     fn init_code(atten: Attenuation) -> Option<u16> {
         Efuse::rtc_calib_init_code(1, atten)
@@ -502,9 +506,13 @@ impl super::AdcCalEfuse for crate::peripherals::ADC1<'_> {
     fn cal_code(atten: Attenuation) -> Option<u16> {
         Efuse::rtc_calib_cal_code(1, atten)
     }
+
+    fn coeff_b(atten: Attenuation) -> Option<i32> {
+        Efuse::rtc_calib_coeff_b(1, atten)
+    }
 }
 
-#[cfg(esp32s3)]
+#[cfg(any(esp32s2, esp32s3))]
 impl super::AdcCalEfuse for crate::peripherals::ADC2<'_> {
     fn init_code(atten: Attenuation) -> Option<u16> {
         Efuse::rtc_calib_init_code(2, atten)
@@ -517,6 +525,9 @@ impl super::AdcCalEfuse for crate::peripherals::ADC2<'_> {
     fn cal_code(atten: Attenuation) -> Option<u16> {
         Efuse::rtc_calib_cal_code(2, atten)
     }
+    fn coeff_b(atten: Attenuation) -> Option<i32> {
+        Efuse::rtc_calib_coeff_b(2, atten)
+    }
 }
 
 mod adc_implementation {