Illegal instruction on Jetson Nano, don't show camera if no display connected

Author: janjongboom

examples/image/classify-full-frame.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import device_patches       # Device specific patches for Jetson Nano (needs to be before importing cv2)
+
 import cv2
 import os
 import sys, getopt
@@ -8,7 +10,6 @@
 from edge_impulse_linux.image import ImageImpulseRunner
 
 runner = None
-show_camera = False
 
 def now():
     return round(time.time() * 1000)

examples/image/classify-image.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import device_patches       # Device specific patches for Jetson Nano (needs to be before importing cv2)
+
 import cv2
 import os
 import sys, getopt

examples/image/classify.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import device_patches       # Device specific patches for Jetson Nano (needs to be before importing cv2)
+
 import cv2
 import os
 import sys, getopt
@@ -8,7 +10,10 @@
 from edge_impulse_linux.image import ImageImpulseRunner
 
 runner = None
+# if you don't want to see a camera preview, set this to False
 show_camera = True
+if (sys.platform == 'linux' and not os.environ.get('DISPLAY')):
+    show_camera = False
 
 def now():
     return round(time.time() * 1000)

examples/image/device_patches.py

@@ -0,0 +1,15 @@
+import os
+
+def get_device():
+    # On Jetson Nano `OPENBLAS_CORETYPE=ARMV8` needs to be set, otherwise including OpenCV
+    # throws an illegal instruction error
+    if (os.path.exists('/proc/device-tree/model')):
+        with open('/proc/device-tree/model', 'r') as f:
+            model = f.read()
+            if ('NVIDIA Jetson Nano' in model):
+                return 'jetson-nano'
+    return 'unknown'
+
+device = get_device()
+if (device == 'jetson-nano'):
+    os.environ['OPENBLAS_CORETYPE'] = 'ARMV8'