Diff: main.cpp

Revision:

0:a606cf2249ad

Child:

1:e5373c63f642

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Dec 31 02:45:31 2014 +0000
@@ -0,0 +1,50 @@
+// Cycle through a 7-segment LCD display
+
+#include "mbed.h"
+
+// Outputs used as input values to the 7-segment binary decoder
+DigitalOut signal[4] = {p17, p18, p19, p20};
+
+// For latching the 7 segment led's output
+DigitalOut latch(p16);
+
+// To show that the mbed is running
+DigitalOut status_led(LED1);
+
+// Function for writing a number to the 7-segment display
+void writeSegment(uint8_t val)
+{
+    // write out the new value
+    for (int i=0; i<4; i++)
+        signal[i] = ((1<<i) & (val)) & 0x0F;
+
+    // latch the value
+    for (int i=0; i<2; i++)
+        latch = !latch;
+}
+
+int main()
+{
+    latch = 0;  // initialize the latch pin for the CD4511B decoder
+    status_led = 0; // initialize & turn off led for startup operations
+
+    uint8_t channel;    // limit to 4 bits (0x00 to 0x0F)
+    channel = 8;    // light up all of the 7-segment's segments at startup - allows for the user to detect if there's a problem
+    writeSegment(channel);
+    wait(1.0);  // wait 2 seconds to ensure user sees the startup operation
+
+    channel = 0;    // start back over at 0
+
+    while(1) {
+        // send numerical value to 7-segment & hold for a while
+        writeSegment(channel++);
+        wait(0.3);
+        status_led = !status_led;
+        
+        // wait again just so that the status led and segment are out of sync
+        wait(0.2);
+        
+        // reset value if too high
+        channel = channel > 9 ? 0 : channel;
+    }
+}
\ No newline at end of file