Revision 110:a930767c281c, committed 2021-10-01

Comitter:

CSTritt

Date:

Fri Oct 01 03:05:20 2021 +0000

Parent:

109:b061f9830736

Commit message:

First Mbed v. 5 version.

Changed in this revision

--- a/main.cpp	Fri Oct 01 02:45:38 2021 +0000
+++ b/main.cpp	Fri Oct 01 03:05:20 2021 +0000
@@ -1,29 +1,43 @@
 /*
-Project: 21_Button-v5
+Project: 21_TimerTest2_v5
 File: main.cpp
-
-Toogles LED1 when USER_BUTTON is tapped. Note LED1 is also PA_5 which is
-also D13. Based on built-in mbed example Nucleo_read_button. Holding the button 
-down will result in LED flashing.
+ 
+Tests timer peformance. Display new time difference with each button press
+and release. Differences of 4 or 5 microseconds are typical.
 
-Modified 12 Aug 2017 by Dr. Sheila Ross
-Last revised 9/30/21 by Dr. C. S. Tritt
+Last modified 9/30/21 by C. S. Tritt (v. 1.0)
 */
-
 #include "mbed.h"
-
-// Construct a digital input linked to the USER_BUTTON.
-DigitalIn myButton(USER_BUTTON); // Built in blue button.
-
-// Construct a digital output linked to LED1.
-DigitalOut myLed(LED1); // Built-in green LED.
-
+ 
+// Construct a USER_BUTTON digital input.
+DigitalIn myButton(USER_BUTTON);
+ 
+// Construct a timer object.
+Timer myTimer;
+ 
+// Construct a transmit only serial connection over our USB.
+Serial pc(USBTX, NC, 9600);
+ 
 int main()
 {
+    myTimer.start();  // Start the timer.
+ 
     while(true) { // Main loop.
-        if (myButton == 0) { // Button is active low.
-            myLed = !myLed; // Toggle LED on/off.
-            ThisThread::sleep_for(100);  // Avoid double-tap, 0.1 seconds.
+        if (myButton == 0) { // Button is pressed (active low).
+            // Save the time on timer.
+            int firstTime = myTimer.read_us();
+            int secondTime = myTimer.read_us();
+                     
+            // Send the time as text via the serial port.
+            pc.printf("Time difference %i microseconds.\n", secondTime - 
+                firstTime );
+            
+             // Reset the timer.
+            myTimer.reset();
+                     
+            // Wait for the user to release the button.
+            while(myButton == 0) {
+            }
         }
     }
 }
\ No newline at end of file