Added examples for Switch object (USR button)

mithru · mithru · commit 6b391b216b60 · 2014-08-18T01:19:48.000+08:00
diff --git a/02.Inputs/SwitchCallback/boot.py b/02.Inputs/SwitchCallback/boot.py
@@ -0,0 +1 @@
+import pyb
diff --git a/02.Inputs/SwitchCallback/main.py b/02.Inputs/SwitchCallback/main.py
@@ -0,0 +1,31 @@
+# USR button is controlled using a Switch object
+# This is the one closer to the center of the pyboard
+sw = pyb.Switch()
+led = pyb.LED(4) # 4 is the blue LED
+
+# toggles the LED when the USR button is released
+# no need for while True: statement to keep this running
+# read up on interrupts to understand how the below statement works
+sw.callback(lambda:led.toggle())
+
+'''
+INTERRUPTS: 
+to put it simply, when a function is registered with callback(), 
+the microcontroller listens to a state change (low to high) on the USR button and registers this change. 
+It then pauses any running code, executes the set function and resume code as usual
+'''
+
+'''
+LAMBDA:
+Python supports the creation of anonymous functions using lambda.
+The above script could be rewritten to support user-defined functions as shown below.
+Comment out the above script and uncomment the script below, and load it on your pyboard.
+'''
+
+
+'''
+def toggleLED():
+	pyb.LED(4).toggle()
+
+sw.callback(toggleLED)
+'''
diff --git a/02.Inputs/SwitchObject/boot.py b/02.Inputs/SwitchObject/boot.py
@@ -0,0 +1 @@
+import pyb
diff --git a/02.Inputs/SwitchObject/main.py b/02.Inputs/SwitchObject/main.py
@@ -0,0 +1,11 @@
+# USR button is controlled using a Switch object
+# This is the one closer to the center of the pyboard
+sw = pyb.Switch()
+led = pyb.LED(4) # 4 is the blue LED
+
+# LED is on only when the USR button is pressed down
+while True:
+	if sw() == True:
+		led.on()
+	else:
+		led.off()
