Fix PR #208 review-thread findings

Author: Copilot

src/sdcard/sdcard.c

@@ -9,6 +9,7 @@
 #include "fatfs/ff.h"
 #include "fatfs/ffconf.h"
 #include "sd_spi.h"
+#include "sdcard.h"
 
 #define SFN_MAX 8
 #define SFN_SUFFIX_LEN 4 // Period + at most three chars.
@@ -18,6 +19,7 @@
 #define CONFIG_FILENAME "PSLAB.CFG"
 
 static bool s_mounted = false;
+static FATFS s_standalone_drive;
 static TCHAR s_sector_buf[BUF_MAX];
 _Static_assert(
     sizeof(s_sector_buf) == 512,
@@ -172,8 +174,7 @@ response_t SDCARD_standalone_check(void) {
         return FAILED;
     }
 
-    FATFS drive;
-    if (f_mount(&drive, SDCARD_DRIVE, 1) != FR_OK) {
+    if (f_mount(&s_standalone_drive, SDCARD_DRIVE, 1) != FR_OK) {
         return FAILED;
     }
     s_mounted = true;

src/sdcard/sdcard.h

@@ -102,10 +102,12 @@ response_t SDCARD_get_file_info(void);
  * 
  * @details Checks if the SD-card can be mounted and if the configuration file is present and valid.
  *          If the configuration file is not present or invalid, or if the SD-card is not mounted, the function returns FAILED.
- *          The configuration file is expected to be named "PSLAB.CFG" and contain a magic header of 5 bytes with a null terminator.
+ *          The configuration file is expected to be named "PSLAB.CFG" and
+ *          contain the 5-byte magic header "PSLAB".
  * 
- * @return SUCCESS
+ * @return SUCCESS or FAILED
  */
 response_t SDCARD_standalone_check(void);
+void SDCARD_standalone_unmount(void);
 
 #endif // _SDCARD_H

src/states.c

@@ -45,6 +45,7 @@ state_t Standalone(void) {
         return STATE_RUNCOMMAND;
     }
 
+    WATCHDOG_TimerClear();
     return STATE_STANDALONE;
 }