TOM SPARKS
A little twist on the blinky program using DigitalOut, PWM, and InterruptIn. User can experiment with various parameters to learn about the Mbed platform and their own hardware. User needs to supply a single wire to connect between two pins to make the light blink. PWM makes pulses that are wired to another pin with an interrupt attached to it. Upon receipt of the pulse, the interrupt calls a function to toggle the blue light off and on. Upon return from the function the program loops to await the next pulse. Lots of remarks explaining what is going on in the program.
Revision 0:faab03ae0c8a, committed 2015-02-04
- Comitter:
- Glued
- Date:
- Wed Feb 04 23:19:25 2015 +0000
- Commit message:
- V1.0 of new blinky program with annotations.
Changed in this revision
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
| mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
diff -r 000000000000 -r faab03ae0c8a main.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Wed Feb 04 23:19:25 2015 +0000
@@ -0,0 +1,86 @@
+#include "mbed.h"
+
+/* THIS PROGRAM IS WRITTEN FOR THE FRDM-Kl25Z BUT CAN BE ADAPTED TO ANY MBED BOARD
+
+ To use this program you need to add a bit of hardware: A single wire from "D1" to "D3."
+
+
+ Here's how it works: The PWN, the interrupt, and the LED are all set up with the first three lines.
+
+ Next, a one-line function is defined to toggle the blue LED.
+
+ The program enters the main() program area and makes sure the blue light is turned off.
+ Yep, on this system apparently '1' means OFF and '0' means 'ON.'
+
+ Next, the PWM parameters are set followed by the interrupt parameters
+
+ Then, the program enters an endless while() loop with nothing in it.
+
+ Upon reset, the PWM begins sending a steady pulse out of the PTD5 pin
+
+ If PTD5 pulses "high" and is connected to the PTD3 pin then it triggers an interrupt which directs
+ program control to the toggler() function which toggles the blue LED, (it turns it 'ON' if it is already 'OFF'
+ or turns it 'OFF' if it is already 'ON.')
+
+ After returning from the interrupt handling routine, toggler(), the program returns to the while() loop
+ to await the next interrupt.
+
+ Experiment with removing the wire from PTD5 and connecting the free end to ground.
+
+ Try changing the LED DigitalOut assignment from PTD1 to PTB19 or PTB18.
+
+ Look up the functions and fiddle around with the PWM parameters.
+
+ BTW, "PT" as in "PTB19" or "PTD3" stands for "PORT." And the "D" or "B" stands for Port D or Port B.
+ The number after it is its pin number in the port. So, PTB18 means Port B pin #18.
+*/
+
+
+ // The PWM setup for PTD5
+ // PTD5 is the "D5" pin
+ // on the FRDM-KL25Z
+
+PwmOut pulseout(PTD5);
+
+ // The interrupt setup for PTD3
+ // PTD3 is the "D3" pin
+ // on the FRDM-KL25Z
+InterruptIn pulsein(PTD3);
+
+ // The LED that will be
+ // toggled to indicate
+ // an incoming pulse from
+ // the PTD5 pin to the
+ // PTD3 pin.
+ // PTD1 is the blue
+ // LED on the FRDM-KL25Z
+DigitalOut blue(PTD1);
+
+
+ // The LED toggling function
+void toggler(){ blue = !blue; }
+
+int main() {
+
+ blue = 1;
+
+ // PWM pin parameters
+ pulseout.period_ms(20); // total pulse time "OFF" and "ON".
+ pulseout.pulsewidth_ms(10); // pulse "ON" time.
+
+ // Interrupt pin parameters
+
+ // Pin is set to pull up
+ pulsein.mode(PullNone);
+ // Pin triggers an intertupt
+ // the rising edge and turns
+ // control over to the
+ // function toggler().
+ pulsein.rise(&toggler);
+
+ // While awaiting an interrupt
+ // the program simply cycles
+ //in an empty while loop.
+while(1) {}
+}
+
diff -r 000000000000 -r faab03ae0c8a mbed.bld --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Wed Feb 04 23:19:25 2015 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/e188a91d3eaa \ No newline at end of file