ad7172: readback after write_reg()

src/ad7172/adc.rs

@@ -42,7 +42,7 @@ 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.write_reg(&regs::AdcMode, &mut adc_mode);
+        adc.write_reg(&regs::AdcMode, &mut adc_mode)?;
 
         Ok(adc)
     }
@@ -87,7 +87,7 @@ impl<SPI: Transfer<u8, Error = E>, NSS: OutputPin, E: fmt::Debug> Adc<SPI, NSS>
         })?;
         let mut offset = <regs::Offset as regs::Register>::Data::empty();
         offset.set_offset(0);
-        self.write_reg(&regs::Offset { index }, &mut offset);
+        self.write_reg(&regs::Offset { index }, &mut offset)?;
         self.update_reg(&regs::Channel { index }, |data| {
             data.set_setup(index);
             data.set_enabled(true);
@@ -154,12 +154,13 @@ impl<SPI: Transfer<u8, Error = E>, NSS: OutputPin, E: fmt::Debug> Adc<SPI, NSS>
                 break;
             }
             // Retry
-            warn!("read_reg checksum error, retrying");
+            warn!("read_reg {:02X}: checksum error: {:?}!={:?}, retrying", reg.address(), checksum_expected, checksum_in);
         }
         Ok(reg_data)
     }
 
     fn write_reg<R: regs::Register>(&mut self, reg: &R, reg_data: &mut R::Data) -> Result<(), AdcError<SPI::Error>> {
+        loop {
             let address = reg.address();
             let mut checksum = Checksum::new(match self.checksum_mode {
                 ChecksumMode::Off => ChecksumMode::Off,
@@ -170,14 +171,16 @@ impl<SPI: Transfer<u8, Error = E>, NSS: OutputPin, E: fmt::Debug> Adc<SPI, NSS>
             checksum.feed(&[address]);
             checksum.feed(&reg_data);
             let checksum_out = checksum.result();
-        loop {
-            let checksum_in = self.transfer(address, reg_data.as_mut(), checksum_out)?;
-            if checksum_in.unwrap_or(0) == 0 {
-                break;
+
+            let mut data = reg_data.clone();
+            let checksum_in = self.transfer(address, data.as_mut(), checksum_out)?;
+
+            let readback_data = self.read_reg(reg)?;
+            if *readback_data == **reg_data {
+                return Ok(());
             }
-            warn!("write_reg: checksum={:02X}, retrying", checksum_in.unwrap_or(0));
+            warn!("write_reg {:02X}: readback error, {:?}!={:?}, retrying", address, &*readback_data, &**reg_data);
         }
-        Ok(())
     }
 
     fn update_reg<R, F, A>(&mut self, reg: &R, f: F) -> Result<A, AdcError<SPI::Error>>

src/ad7172/regs.rs

@@ -8,7 +8,8 @@ pub trait Register {
     type Data: RegisterData;
     fn address(&self) -> u8;
 }
-pub trait RegisterData: Deref<Target=[u8]> + DerefMut {
+
+pub trait RegisterData: Clone + Deref<Target=[u8]> + DerefMut {
     fn empty() -> Self;
 }
 
@@ -26,6 +27,7 @@ macro_rules! def_reg {
         }
         mod $reg {
             /// Register contents
+            #[derive(Clone)]
             pub struct Data(pub [u8; $size]);
             impl super::RegisterData for Data {
                 /// Generate zeroed register contents
@@ -55,6 +57,7 @@ macro_rules! def_reg {
             }
         }
         mod $reg {
+            #[derive(Clone)]
             pub struct Data(pub [u8; $size]);
             impl super::RegisterData for Data {
                 fn empty() -> Self {