ad7172: add calibrate_offset()

src/ad7172/adc.rs

@@ -2,11 +2,10 @@ use core::fmt;
 use embedded_hal::digital::v2::OutputPin;
 use embedded_hal::blocking::spi::Transfer;
 use log::{info, warn};
-use super::checksum::{ChecksumMode, Checksum};
-use super::AdcError;
 use super::{
     regs::{self, Register, RegisterData},
-    Input, RefSource, PostFilter, DigitalFilterOrder,
+    checksum::{ChecksumMode, Checksum},
+    AdcError, Mode, Input, RefSource, PostFilter, DigitalFilterOrder,
 };
 
 /// AD7172-2 implementation
@@ -42,6 +41,7 @@ impl<SPI: Transfer<u8, Error = E>, NSS: OutputPin, E: fmt::Debug> Adc<SPI, NSS>
 
         let mut adc_mode = <regs::AdcMode as Register>::Data::empty();
         adc_mode.set_ref_en(true);
+        adc_mode.set_mode(Mode::ContinuousConversion);
         adc.write_reg(&regs::AdcMode, &mut adc_mode)?;
 
         Ok(adc)
@@ -85,9 +85,6 @@ impl<SPI: Transfer<u8, Error = E>, NSS: OutputPin, E: fmt::Debug> Adc<SPI, NSS>
             data.set_enh_filt(PostFilter::F16SPS);
             data.set_order(DigitalFilterOrder::Sinc5Sinc1);
         })?;
-        let mut offset = <regs::Offset as regs::Register>::Data::empty();
-        offset.set_offset(0);
-        self.write_reg(&regs::Offset { index }, &mut offset)?;
         self.update_reg(&regs::Channel { index }, |data| {
             data.set_setup(index);
             data.set_enabled(true);
@@ -97,6 +94,20 @@ impl<SPI: Transfer<u8, Error = E>, NSS: OutputPin, E: fmt::Debug> Adc<SPI, NSS>
         Ok(())
     }
 
+    /// Calibrates offset registers
+    pub fn calibrate_offset(&mut self) -> Result<(), AdcError<SPI::Error>> {
+        self.update_reg(&regs::AdcMode, |adc_mode| {
+            adc_mode.set_mode(Mode::SystemOffsetCalibration);
+        })?;
+        while ! self.read_reg(&regs::Status)?.ready() {}
+
+        self.update_reg(&regs::AdcMode, |adc_mode| {
+            adc_mode.set_mode(Mode::ContinuousConversion);
+        })?;
+
+        Ok(())
+    }
+
     pub fn get_postfilter(&mut self, index: u8) -> Result<Option<PostFilter>, AdcError<SPI::Error>> {
         self.read_reg(&regs::FiltCon { index })
             .map(|data| {

src/ad7172/mod.rs

@@ -33,6 +33,37 @@ impl<SPI> From<SPI> for AdcError<SPI> {
     }
 }
 
+
+
+#[derive(Clone, Copy, Debug)]
+#[repr(u8)]
+pub enum Mode {
+    ContinuousConversion = 0b000,
+    SingleConversion = 0b001,
+    Standby = 0b010,
+    PowerDown = 0b011,
+    InternalOffsetCalibration = 0b100,
+    Invalid,
+    SystemOffsetCalibration = 0b110,
+    SystemGainCalibration = 0b111,
+}
+
+impl From<u8> for Mode {
+    fn from(x: u8) -> Self {
+        use Mode::*;
+        match x {
+            0b000 => ContinuousConversion,
+            0b001 => SingleConversion,
+            0b010 => Standby,
+            0b011 => PowerDown,
+            0b100 => InternalOffsetCalibration,
+            0b110 => SystemOffsetCalibration,
+            0b111 => SystemGainCalibration,
+            _ => Invalid,
+        }
+    }
+}
+
 #[derive(Clone, Copy, Debug)]
 #[repr(u8)]
 pub enum Input {

src/ad7172/regs.rs

@@ -158,12 +158,12 @@ impl status::Data {
 
 def_reg!(AdcMode, adc_mode, 0x01, 2);
 impl adc_mode::Data {
-    reg_bits!(clockset, set_clocksel, 1, 2..3, "Clock source");
+    reg_bits!(delay, set_delay, 0, 0..=2, "Delay after channel switch");
-    reg_bits!(mode, set_mode, 1, 4..6, "Operating mode");
+    reg_bit!(sing_cyc, set_sing_cyc, 0, 5, "Can only used with single channel");
-    reg_bits!(delay, set_delay, 0, 0..2, "Delay after channel switch");
+    reg_bit!(hide_delay, set_hide_delay, 0, 6, "Hide delay");
-    reg_bit!(sing_cyc, set_sing_cyc, 1, 5, "Can only used with single channel");
-    reg_bit!(hide_delay, set_hide_delay, 1, 6, "Hide delay");
     reg_bit!(ref_en, set_ref_en, 0, 7, "Enable internal reference, output buffered 2.5 V to REFOUT");
+    reg_bits!(clockset, set_clocksel, 1, 2..=3, "Clock source");
+    reg_bits!(mode, set_mode, 1, 4..=6, Mode, "Operating mode");
 }
 
 def_reg!(IfMode, if_mode, 0x02, 2);

src/main.rs

@@ -94,6 +94,7 @@ fn main() -> ! {
     let mut adc = ad7172::Adc::new(pins.adc_spi, pins.adc_nss).unwrap();
     adc.setup_channel(0, ad7172::Input::Ain0, ad7172::Input::Ain1).unwrap();
     adc.setup_channel(1, ad7172::Input::Ain2, ad7172::Input::Ain3).unwrap();
+    adc.calibrate_offset().unwrap();
     let mut dac0 = ad5680::Dac::new(pins.dac0_spi, pins.dac0_sync);
     dac0.set(0).unwrap();
     let mut dac1 = ad5680::Dac::new(pins.dac1_spi, pins.dac1_sync);