Diff: main.cpp

Revision:

1:f4e48249b980

Parent:

0:efe13d6feef8

diff -r efe13d6feef8 -r f4e48249b980 main.cpp
--- a/main.cpp	Tue Oct 03 16:53:41 2017 +0000
+++ b/main.cpp	Tue Oct 03 17:00:33 2017 +0000
@@ -1,12 +1,15 @@
 #include "mbed.h"
 
+// You can write out debug strings via the mbed interface and the built-in mini-USB socket.
 Serial pc(USBTX, USBRX);
 
+// All 4 built-in LEDs defined.
 DigitalOut led1(LED1);
 DigitalOut led2(LED2);
 DigitalOut led3(LED3);
 DigitalOut led4(LED4);
 
+// Example initialisation function
 void initialise()
 {
     // Baud rate not required over USB.
@@ -27,6 +30,15 @@
     wait(1.0f);
 }
 
+// The LED blinking code was split out into 2 functions with different parameter
+// passing methods to incrementally add more sophistication and complexity into
+// the basic mbed_blinky example. Those familiar with C/C++ won't need this sort
+// of help, but if mbed is your first foray into C/C++, this will help...
+
+// Take the parameter passed to us in variable 'val' and use the value in it
+// to update the LEDs. We essentially use the value in 'val' as a bit field
+// telling us which LEDs to light up, in a way that corresponds directly to the
+// bit position.
 void updateLEDs(int val)
 {
     led1 = val & 0x01;
@@ -35,6 +47,10 @@
     led4 = (val & 0x08) >> 3;
 }
 
+// A simple bitwise shifting function to create an LED chaser effect.
+// This function is different as it takes a pointer to the original variable.
+// i.e., it is expecting the address to an int variable, not simply the value
+// itself.
 void advanceLEDs(int *val)
 {
     *val = *val << 1;