fixed RFID reader outputting un-aligned IDs in buffer

src/drivers/nfc_reader.rs

@@ -1,6 +1,6 @@
 use embassy_time::{Duration, Timer};
 use esp_hal::{Async, uart::Uart};
-use log::{debug, info};
+use log::{debug, info, warn};
 
 use crate::TallyPublisher;
 
@@ -18,10 +18,14 @@ pub async fn rfid_reader_task(mut uart_device: Uart<'static, Async>, chan: Tally
                 }
                 info!("Read {n} bytes from UART: {hex_str}");
 
-                // The first byte is always 0x02 (Start of text) 
-                // Followed by 12 Bytes of chars
-                // Ended by 0x03 (End of text)
-                chan.publish(uart_buffer[1..13].try_into().unwrap()).await;
+                match extract_id(&uart_buffer) {
+                    Some(read) => {
+                        chan.publish(read.try_into().unwrap()).await;
+                    }
+                    None => {
+                        warn!("Invalid read from the RFID reader");
+                    }
+                };
             }
             Err(e) => {
                 log::error!("Error reading from UART: {e}");
@@ -30,3 +34,35 @@ pub async fn rfid_reader_task(mut uart_device: Uart<'static, Async>, chan: Tally
         Timer::after(Duration::from_millis(200)).await;
     }
 }
+
+/// Scans the UART output and retuns the first propper read ID
+/// This ensures that only valid ID are parsed
+///
+/// A valid read looks like this:
+/// The first byte is always 0x02 (Start of text)
+/// Followed by 12 Bytes of chars
+/// Ended by 0x03 (End of text)
+pub fn extract_id(buffer: &[u8]) -> Option<[u8; 12]> {
+    const STX: u8 = 0x02; // Start of Text ASCII char
+    const ETX: u8 = 0x03; // End of Text ASCII char
+    const ID_LENGTH: usize = 12;
+    const MINIMUM_SEQUENCE: usize = ID_LENGTH + 2; // STX + 12 bytes + ETX
+
+    if buffer.len() < MINIMUM_SEQUENCE {
+        return None;
+    }
+
+    for window_start in 0..=buffer.len() - MINIMUM_SEQUENCE {
+        if buffer[window_start] == STX {
+            let id_end = window_start + ID_LENGTH + 1;
+
+            if buffer[id_end] == ETX {
+                let mut id = [0u8; ID_LENGTH];
+                id.copy_from_slice(&buffer[window_start + 1..id_end]);
+                return Some(id);
+            }
+        }
+    }
+
+    None
+}

src/init/sd_card.rs

@@ -132,14 +132,17 @@ impl Persistence for SDCardPersistence {
     async fn list_days(&mut self) -> Vec<Day> {
         let mut vol_0 = self.vol_mgr.open_volume(VolumeIdx(0)).unwrap();
         let mut root_dir = vol_0.open_root_dir().unwrap();
-        let mut days_dir = root_dir.open_dir("days").unwrap();
+
+        let mut days_dir = root_dir.open_dir(".").unwrap();
 
         let mut days: Vec<Day> = Vec::new();
         days_dir
             .iterate_dir(|e| {
                 let filename = e.name.clone();
-                let day: Day = filename.try_into().unwrap();
-                days.push(day);
+
+                if let Ok(day) = filename.try_into() {
+                    days.push(day);
+                }
             })
             .unwrap();
 

src/store/day.rs

@@ -3,7 +3,7 @@ use core::fmt::Write;
 use embedded_sdmmc::ShortFileName;
 use serde::{Deserialize, Serialize};
 
-#[derive(Clone, Copy, Serialize, Deserialize, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Serialize, Deserialize, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Day(u32);
 
 impl Day {

src/store/tally_id.rs

@@ -1,4 +1,4 @@
-use core::str::FromStr;
+use core::{fmt::Display, str::FromStr};
 use serde::{Deserialize, Deserializer, Serialize, Serializer, de};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
@@ -72,6 +72,21 @@ impl TryFrom<&[u8]> for TallyID {
     }
 }
 
+impl TryFrom<[u8; 12]> for TallyID {
+    type Error = ();
+
+    fn try_from(value: [u8; 12]) -> Result<Self, Self::Error> {
+        Self::try_from(&value as &[u8])
+    }
+}
+
+impl Display for TallyID {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        let s: heapless::String<12> = (*self).into();
+        write!(f, "{}", s)
+    }
+}
+
 impl Serialize for TallyID {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where