Handle empty EEPROM more gracefully in a few other places (#291) (#292)

* Handle empty EEPROM more gracefully in a few other places

* Add empty EEPROM reference file for future testing

Author: jamwaffles

CHANGELOG.md

@@ -6,6 +6,11 @@ An EtherCAT master written in Rust.
 
 ## [Unreleased] - ReleaseDate
 
+### Fixed
+
+- [#291](https://github.com/ethercrab-rs/ethercrab/pull/291) Allow initialisation to progress
+  further for devices with empty EEPROMs by falling back to defaults if config data cannot be found.
+
 ## [0.5.4] - 2025-03-20
 
 ### Fixed
@@ -465,8 +470,8 @@ An EtherCAT master written in Rust.
 - Initial release
 
 <!-- next-url -->
-[unreleased]: https://github.com/ethercrab-rs/ethercrab/compare/ethercrab-v0.5.4...HEAD
 
+[unreleased]: https://github.com/ethercrab-rs/ethercrab/compare/ethercrab-v0.5.4...HEAD
 [0.5.4]: https://github.com/ethercrab-rs/ethercrab/compare/ethercrab-v0.5.3...ethercrab-v0.5.4
 [0.5.3]: https://github.com/ethercrab-rs/ethercrab/compare/ethercrab-v0.5.2...ethercrab-v0.5.3
 [0.5.2]: https://github.com/ethercrab-rs/ethercrab/compare/ethercrab-v0.5.1...ethercrab-v0.5.2

dumps/issue-286-empty-eeprom-example.bin

@@ -319,7 +319,7 @@ impl EtherCrabWireRead for PortStatuses {
 /// SII "General" category.
 ///
 /// Defined in ETG1000.6 Table 21
-#[derive(Debug, PartialEq, Eq, ethercrab_wire::EtherCrabWireRead)]
+#[derive(Debug, Default, PartialEq, Eq, ethercrab_wire::EtherCrabWireRead)]
 #[wire(bytes = 18)]
 pub struct SiiGeneral {
     #[wire(bytes = 1)]
@@ -372,7 +372,7 @@ pub enum PortStatus {
 }
 
 bitflags::bitflags! {
-    #[derive(Debug, PartialEq, Eq)]
+    #[derive(Debug, Default, PartialEq, Eq)]
     pub struct Flags: u8 {
         const ENABLE_SAFE_OP = 0x01;
         const ENABLE_NOT_LRW = 0x02;
@@ -401,7 +401,7 @@ impl EtherCrabWireRead for Flags {
 }
 
 bitflags::bitflags! {
-    #[derive(Debug, PartialEq, Eq)]
+    #[derive(Debug, Default, PartialEq, Eq)]
     pub struct CoeDetails: u8 {
         /// Bit 0: Enable SDO
         const ENABLE_SDO = 0x01;

src/eeprom/types.rs

@@ -436,3 +436,18 @@ impl From<ethercrab_wire::WireError> for Error {
         Self::Wire(value)
     }
 }
+
+/// Turn [`EepromError::NoCategory`] errors into `None`.
+pub(crate) trait IgnoreNoCategory<T> {
+    fn ignore_no_category(self) -> Result<Option<T>, Error>;
+}
+
+impl<T> IgnoreNoCategory<T> for Result<T, Error> {
+    fn ignore_no_category(self) -> Result<Option<T>, Error> {
+        match self {
+            Ok(result) => Ok(Some(result)),
+            Err(Error::Eeprom(EepromError::NoCategory)) => Ok(None),
+            Err(e) => return Err(e),
+        }
+    }
+}

src/error.rs

@@ -2,10 +2,10 @@ use super::{SubDevice, SubDeviceRef};
 use crate::{
     coe::{SdoExpedited, SubIndex},
     eeprom::types::{
-        CoeDetails, FmmuUsage, MailboxProtocols, Pdo, SiiOwner, SyncManager, SyncManagerEnable,
-        SyncManagerType,
+        CoeDetails, DefaultMailbox, FmmuUsage, MailboxProtocols, Pdo, SiiGeneral, SiiOwner,
+        SyncManager, SyncManagerEnable, SyncManagerType,
     },
-    error::{Error, Item},
+    error::{Error, IgnoreNoCategory, Item},
     fmmu::Fmmu,
     fmt,
     pdi::{PdiOffset, PdiSegment},
@@ -208,10 +208,34 @@ where
 
     /// Configure SM0 and SM1 for mailbox communication.
     async fn configure_mailbox_sms(&mut self, sync_managers: &[SyncManager]) -> Result<(), Error> {
+        let eeprom = self.eeprom();
+
         // Read default mailbox configuration from SubDevice information area
-        let mailbox_config = self.eeprom().mailbox_config().await?;
+        let mailbox_config = eeprom
+            .mailbox_config()
+            .await
+            .ignore_no_category()?
+            .unwrap_or_else(|| {
+                fmt::debug!(
+                    "{:#06x} has no EEPROM mailbox config, using default",
+                    self.configured_address()
+                );
+
+                DefaultMailbox::default()
+            });
 
-        let general = self.eeprom().general().await?;
+        let general = eeprom
+            .general()
+            .await
+            .ignore_no_category()?
+            .unwrap_or_else(|| {
+                fmt::debug!(
+                    "{:#06x} has no EEPROM general category, using default",
+                    self.configured_address()
+                );
+
+                SiiGeneral::default()
+            });
 
         fmt::trace!(
             "SubDevice {:#06x} Mailbox configuration: {:#?}",

src/subdevice/configuration.rs

@@ -7,7 +7,7 @@ use crate::{
         types::{FmmuEx, FmmuUsage, Pdo, PdoType, SyncManager},
         ChunkReader, EepromDataProvider,
     },
-    error::{EepromError, Error, Item},
+    error::{EepromError, Error, IgnoreNoCategory, Item},
     fmt,
     subdevice::SubDeviceIdentity,
 };
@@ -69,7 +69,7 @@ where
             // Heuristic: if every category we search for is empty, it's likely that the EEPROM is
             // blank and we should stop searching for anything.
             if num_empty_categories >= 32 {
-                fmt::debug!(
+                fmt::trace!(
                     "Did not find any non-empty categories. EEPROM could be empty or corrupt."
                 );
 
@@ -119,7 +119,11 @@ where
         // longer.
         let name_idx = 1;
 
-        self.find_string(name_idx).await
+        Ok(self
+            .find_string(name_idx)
+            .await
+            .ignore_no_category()?
+            .flatten())
     }
 
     pub(crate) async fn mailbox_config(&self) -> Result<DefaultMailbox, Error> {