Add single LED blink on succesful boot, add hotplug support.

README.md

@@ -13,8 +13,9 @@ Log messages are stored in `azullog.txt`, which is cleared on every boot.
 Normally only basic initialization information is stored, but turning `DIPSW2` on will cause every SCSI command to be logged.
 
 The indicator LED will normally report disk access.
-It also reports following error conditions:
+It also reports following status conditions:
 
+- 1 fast blink on boot: Image file loaded successfully
 - 3 fast blinks: No images found on SD card
 - 5 fast blinks: SD card not detected
 - Continuous morse pattern: firmware crashed, morse code indicates crash location
@@ -44,14 +45,22 @@ Example format for config file:
 
 Performance
 -----------
-With verbose log messages disabled, expected SCSI performance is 1.7 MB/s read and 1.5 MB/s write.
+With verbose log messages disabled, expected SCSI performance is 2.4 MB/s read and 1.5 MB/s write.
 Slow SD card or fragmented filesystem can slow down access.
 
 Seek performance is best if image files are contiguous.
 For ExFAT filesystem this relies on a file flag set by PC.
 Current versions of exfat-fuse on Linux have an [issue](https://github.com/relan/exfat/pull/101) that causes the files not to be marked contiguous even when they are.
 This is indicated by message `WARNING: file HD00_512.hda is not contiguous. This will increase read latency.` in the log.
 
+Hotplugging
+-----------
+The firmware supports hot-plug removal and reinsertion of SD card.
+The status led will blink continuously when card is not present, then blink once when card is reinserted successfully.
+
+It will depend on the host system whether it gets confused by hotplugging.
+Any IO requests issued when card is removed will be timeouted.
+
 Programming
 -----------
 The AzulSCSI v1 board can be programmed using USB connection in DFU mode.

src/AzulSCSI.cpp

@@ -941,7 +941,15 @@ void scsi_loop()
   }
 
   // Wait until RST = H, BSY = H, SEL = L
-  while (SCSI_IN(BSY) || !SCSI_IN(SEL) || SCSI_IN(RST));
+  uint32_t start = millis();
+  while (SCSI_IN(BSY) || !SCSI_IN(SEL) || SCSI_IN(RST))
+  {
+    if ((uint32_t)(millis() - start) > 1000)
+    {
+      // Service main loop while waiting for request
+      return;
+    }
+  }
 
   // BSY+ SEL-
   // If the ID to respond is not driven, wait for the next
@@ -1184,7 +1192,7 @@ int main(void)
     do
     {
       blinkStatus(BLINK_ERROR_NO_SD_CARD);
-      delay(5000);
+      delay(1000);
     } while (!SD.begin(SD_CONFIG));
     azlog("SD card init succeeded after retry");
   }
@@ -1204,12 +1212,41 @@ int main(void)
   logfile = SD.open(LOGFILE, O_WRONLY | O_CREAT | O_TRUNC);
   saveLog(logfile);
 
+  if (g_scsi_id_mask != 0)
+  {
+    // Ok, there is an image
+    blinkStatus(1);
+  }
+
   uint32_t prev_log_save = millis();
 
   while (1)
   {
     scsi_loop();
 
+    // Check SD card status for hotplug
+    uint32_t ocr;
+    if (!SD.card()->readOCR(&ocr))
+    {
+      if (!SD.card()->readOCR(&ocr))
+      {
+        azlog("SD card removed, trying to reinit");
+        do
+        {
+          blinkStatus(BLINK_ERROR_NO_SD_CARD);
+          delay(1000);
+        } while (!SD.begin(SD_CONFIG));
+        azlog("SD card reinit succeeded");
+        readSCSIDeviceConfig();
+        findHDDImages();
+
+        if (g_scsi_id_mask != 0)
+        {
+          blinkStatus(1);
+        }
+      }
+    }
+
     // Save log once a second if there are new log messages
     if ((uint32_t)(millis() - prev_log_save) > 1000)
     {

utils/run_gdb.sh

@@ -5,6 +5,7 @@
 
 killall orbuculum
 killall orbcat
+rm -f swo.log
 
 arm-none-eabi-gdb \
        -iex 'target extended | openocd -f interface/stlink.cfg -f target/stm32f1x.cfg -c "gdb_port pipe"' \