mimxrt/sdcard: Fix power-up issue.

Fixed card detection issue at startup caused by debouncing
of card detection signals by adding 2ms delay.

ports/mimxrt/machine_sdcard.c

@@ -28,6 +28,7 @@
 #include "py/runtime.h"
 #include "py/mperrno.h"
 #include "extmod/vfs.h"
+#include "ticks.h"
 #include "fsl_cache.h"
 
 #include "sdcard.h"
@@ -72,6 +73,9 @@ STATIC bool machine_sdcard_init_helper(mimxrt_sdcard_obj_t *self, const mp_arg_v
     sdcard_init_pins(self);
 
     self->initialized = false;
+
+    ticks_delay_us64(2ULL * 1000ULL);  // Wait 2ms to allow USDHC signals to settle/debounce
+
     return sdcard_detect(self);
 }
 

ports/mimxrt/modules/_boot.py

@@ -5,6 +5,7 @@
 import os
 import sys
 import mimxrt
+from machine import Pin
 
 bdev = mimxrt.Flash()
 try:
@@ -16,18 +17,18 @@
 os.chdir("/flash")
 sys.path.append("/flash")
 
-# do not mount the SD card if SKIPSD exists and SDCard module is available.
+# do not mount the SD card if SKIPSD exists.
 try:
-    from machine import SDCard
-
     os.stat("SKIPSD")
 except:
-    sdcard = SDCard(1)
-    if sdcard:
-        try:
+    try:
+        from machine import SDCard
+
+        sdcard = SDCard(1)
+        if sdcard:
             fat = os.VfsFat(sdcard)
             os.mount(fat, "/sdcard")
             os.chdir("/sdcard")
             sys.path.append("/sdcard")
-        except:
-            print("Mounting SD card failed")
+    except:
+        pass  # Fail silently