Added UART test script, updated comment in example

CircuitPython_Quick_Starts/CircuitPython_UART.py

@@ -1,4 +1,4 @@
-# Gemma IO demo - USB/Serial echo
+# CircuitPython Demo - USB/Serial echo
 
 import digitalio
 import board

CircuitPython_Quick_Starts/UART_Test_Script.py

@@ -0,0 +1,38 @@
+import board
+import busio
+
+
+def is_hardware_UART(tx, rx):
+    try:
+        p = busio.UART(tx, rx)
+        p.deinit()
+        return True
+    except ValueError:
+        return False
+
+
+def get_unique_pins():
+    pin_names = dir(board)
+    if "NEOPIXEL" in pin_names:
+        pin_names.remove("NEOPIXEL")
+    if "APA102_MOSI" in pin_names:
+        pin_names.remove("APA102_MOSI")
+    if "APA102_SCK" in pin_names:
+        pin_names.remove("APA102_SCK")
+    pins = [getattr(board, p) for p in pin_names]
+    unique = []
+    for p in pins:
+        if p not in unique:
+            unique.append(p)
+    return unique
+
+
+for tx_pin in get_unique_pins():
+    for rx_pin in get_unique_pins():
+        if rx_pin is tx_pin:
+            continue
+        else:
+            if is_hardware_UART(tx_pin, rx_pin):
+                print("RX pin:", rx_pin, "\t TX pin:", tx_pin)
+            else:
+                pass