Diff: main.cpp

Revision:

7:031078522195

Parent:

6:0c1ab2c11252

Child:

8:8a2d07e4a8c3

--- a/main.cpp	Wed Sep 13 10:32:11 2017 +0000
+++ b/main.cpp	Fri Oct 20 17:27:02 2017 +0000
@@ -1,29 +1,91 @@
 /*
-    Project: BinaryCount
+    Project: FlexiBarDemo
     File: main.cpp
-    
-    Displays 4 bit binary count on bar graph display.
-    
+
+    Test harness for flexiBar bar graph display function.
+
     Written by: Dr. C. S. Tritt
     Created: 9/13/17 (v. 1.0)
 */
 #include "mbed.h"
 
-BusOut barGraph(D5, D4, D3, D2);  // Create barGraph BusOut object.
-DigitalOut pinD7(D7);  // Needed to force this pin off.
+// Create 10-bit BusOut object called barGraph.
+BusOut barGraph(D11, D10, D9, D8, D7, D6, D5, D4, D3, D2);
+
+// Displays specified digit on theBar. Returns non-zero in case of errors. Mbed 
+// objects generally must be based by reference. See function definition for 
+// more information.
+int flexiBar(int value, BusOut &theBar, bool single, bool active);
 
 int main() {
 
-    printf("Binary count example\n"); // ID software.
+    printf("flexiBar Test Harness\n"); // ID software.
     
-    pinD7 = 0; // Force pin D7 off. This shouldn't be necessary.
+    // Start by directly testing the display.
+    barGraph = 0b1111111111;  // Light all bars.
+    wait(2.0);
+    barGraph = 0;  // All bars off.
+    wait(2.0);
     
-    barGraph = 0;  // Light top bar.
+    // Loop through all values in both modes.
     while(true) {
-        barGraph = barGraph + 1; // Add one to count.
-        wait(1.0);
-        if (barGraph == 15) {
-            barGraph = 0;
+        bool single = true;
+        for (int n = 0; n <= 9; n++) {
+            flexiBar(n, barGraph, single, true);
+            wait(1.0);
+        }
+        single = false;
+        for (int n = 0; n <= 9; n++) {
+            flexiBar(n, barGraph, single, true);
+            wait(1.0);
+        }
+        // Test the special case of all bars off. Third argument is ignored.
+        flexiBar(-1, barGraph, false, true);
+        wait(2.0);   
+    }
+}
+
+int flexiBar(int value, BusOut &theBar, bool single, bool active) {
+/*
+    Function: flexiBar (v. 1.0)
+    Created by: Dr. C. S. Tritt, 10/20/17
+    
+    Displays value (range 0 to 9) on the specified bar graph display. If solid 
+    is true, all the lower order bars will be on. Otherwise they will be off. 
+    Active being true indicates the display is wired active high. Otherwise, it
+    is assumed to be active low. To assure display is operational, the 
+    display will show at least one bar lit at all times (0 is indicated by a 
+    single bar and 9 by 10 bars). A special case is a value of -1 which will 
+    light no bars.
+    
+    I previously thought pow would be better than left shift (<<), but now I see
+    that left shift really is the best approach.
+    
+    Mbed objects generally must be passed by reference (with &).
+    
+    Pass theBar (rather than use a global symbol) for flexibility.
+    
+    Note there are 2 returns in this function! One for value being out of range
+    errors. The other for no error.
+*/
+    if (value < -1 || value > 9) return -1; // Value out of range error.
+    
+    int output; // Use variable to make active low case easy to compute.
+    
+    if (value == -1) {
+        output = 0;  // Special case of all bars off.
+    } else {
+        if (single) {
+             output = 1 << value; // Light single bars by shifting 1 left.
+        } else {
+             output = (1 << (value + 1)) - 1; // Light a stack of bars.
         }
     }
-}
\ No newline at end of file
+    
+    if (active) { // Deal with active low vs. active high.
+        theBar = output;
+    } else {
+        theBar = ~output; // Invert bits for actived low.
+    }
+    return 0; // 
+}    
\ No newline at end of file