add exception output

ledmatrix.py

@@ -75,13 +75,8 @@ class LedMatrix:
 		# The LEDs are laid out in a long string going from north to south,
 		# one step to the east, and then south to north, before thxy	e cycle
 		# starts over.
-		stride = self.stride
 		phys_addr = int(((x)%self.panelcolumn) + ((y)*self.panelcolumn) + (self.round_down((x)/self.panelcolumn) * self.panelcolumn * self.panelcolumn))
 
-		# if x & 1:
-		# 	phys_addr += stride - 1 - y
-		# else:
-		# 	phys_addr += y
 		return phys_addr
 
 	def get_pixel(self, x, y):

main.py

@@ -47,6 +47,7 @@ else:
 	except:
 		# ...else assume that there's an MCU (driving the display) connected
 		# to a serial port
+		print('HAL: failed: {}'.format(e.args[0]))
 		from arduinoserialhal import ArduinoSerialHAL as HAL
 
 gc.collect()