Charles Tritt / Mbed 2 deprecated FlexiBarDemo

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Dependencies:   mbed

Fork of BinaryCount by Charles Tritt

flexiBar.cpp@8:8a2d07e4a8c3, 2017-10-23 (annotated)

Committer:
CSTritt
Date:
Mon Oct 23 19:10:39 2017 +0000
Revision:
8:8a2d07e4a8c3
Child:
9:d87a0d02a0ac
Improved opening comments. Changed out-of-range error indication from -1 to 1.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
CSTritt 8:8a2d07e4a8c3 1 /*
CSTritt 8:8a2d07e4a8c3 2 Project: FlexiBarDemo
CSTritt 8:8a2d07e4a8c3 3 File: flexiBar.cpp
CSTritt 8:8a2d07e4a8c3 4 Function: flexiBar (v. 1.1)
CSTritt 8:8a2d07e4a8c3 5 Created by: Dr. C. S. Tritt, 10/22/17
CSTritt 8:8a2d07e4a8c3 6
CSTritt 8:8a2d07e4a8c3 7 This function displays an integer value (range 0 to 9) on the specified bar
CSTritt 8:8a2d07e4a8c3 8 graph display.
CSTritt 8:8a2d07e4a8c3 9
CSTritt 8:8a2d07e4a8c3 10 Precondition(s):
CSTritt 8:8a2d07e4a8c3 11
CSTritt 8:8a2d07e4a8c3 12 Physical bar graph display correctly wired to digital output pins.
CSTritt 8:8a2d07e4a8c3 13 BusOut object that collects display output pins.
CSTritt 8:8a2d07e4a8c3 14
CSTritt 8:8a2d07e4a8c3 15 Postcondition(s):
CSTritt 8:8a2d07e4a8c3 16
CSTritt 8:8a2d07e4a8c3 17 Bar graph display is left showing the appropriate output.
CSTritt 8:8a2d07e4a8c3 18
CSTritt 8:8a2d07e4a8c3 19 Arguments/Parameters:
CSTritt 8:8a2d07e4a8c3 20
CSTritt 8:8a2d07e4a8c3 21 int value - Value to be displayed. Range -1 to 9, inclusive.
CSTritt 8:8a2d07e4a8c3 22 BusOut &theBar - Bus created from connected GPIO output pins.
CSTritt 8:8a2d07e4a8c3 23 bool single - Single vs. stacked display format. True indicates single.
CSTritt 8:8a2d07e4a8c3 24 bool active - Active high flag. True indicates active high.
CSTritt 8:8a2d07e4a8c3 25
CSTritt 8:8a2d07e4a8c3 26 Returns (& Error Handling):
CSTritt 8:8a2d07e4a8c3 27
CSTritt 8:8a2d07e4a8c3 28 0 - Normal operation.
CSTritt 8:8a2d07e4a8c3 29 1 - Error, value out of range.
CSTritt 8:8a2d07e4a8c3 30
CSTritt 8:8a2d07e4a8c3 31 Notes:
CSTritt 8:8a2d07e4a8c3 32
CSTritt 8:8a2d07e4a8c3 33 To assure display is operational, at least one bar will always be lit
CSTritt 8:8a2d07e4a8c3 34 (0 is indicated by a single bar and 9 by 10 bars). A special case is the
CSTritt 8:8a2d07e4a8c3 35 the value -1, which will light no bars.
CSTritt 8:8a2d07e4a8c3 36
CSTritt 8:8a2d07e4a8c3 37 I previously thought pow would be better than left shift (<<), but now I see
CSTritt 8:8a2d07e4a8c3 38 that left shift really is the best approach.
CSTritt 8:8a2d07e4a8c3 39
CSTritt 8:8a2d07e4a8c3 40 Mbed objects generally must be passed by reference (with &). This prevents
CSTritt 8:8a2d07e4a8c3 41 there possibly two or more instances of the objects possibly having
CSTritt 8:8a2d07e4a8c3 42 conflicting states.
CSTritt 8:8a2d07e4a8c3 43
CSTritt 8:8a2d07e4a8c3 44 Pass theBar (rather than using the global symbol) for flexibility.
CSTritt 8:8a2d07e4a8c3 45
CSTritt 8:8a2d07e4a8c3 46 Note there are 2 returns in this function! One for value being out of range
CSTritt 8:8a2d07e4a8c3 47 errors. The other for no error.
CSTritt 8:8a2d07e4a8c3 48 */
CSTritt 8:8a2d07e4a8c3 49 #include "mbed.h"
CSTritt 8:8a2d07e4a8c3 50
CSTritt 8:8a2d07e4a8c3 51 int flexiBar(int value, BusOut &theBar, bool single, bool active)
CSTritt 8:8a2d07e4a8c3 52 {
CSTritt 8:8a2d07e4a8c3 53
CSTritt 8:8a2d07e4a8c3 54 if (value < -1 || value > 9) return 1; // Indicate value out-of-range error.
CSTritt 8:8a2d07e4a8c3 55
CSTritt 8:8a2d07e4a8c3 56 int output; // Use variable to make active low case easy to compute.
CSTritt 8:8a2d07e4a8c3 57
CSTritt 8:8a2d07e4a8c3 58 if (value == -1) {
CSTritt 8:8a2d07e4a8c3 59 output = 0; // Special case of all bars off.
CSTritt 8:8a2d07e4a8c3 60 } else {
CSTritt 8:8a2d07e4a8c3 61 if (single) {
CSTritt 8:8a2d07e4a8c3 62 output = 1 << value; // Light single bars by shifting 1 left.
CSTritt 8:8a2d07e4a8c3 63 } else {
CSTritt 8:8a2d07e4a8c3 64 output = (1 << (value + 1)) - 1; // Light a stack of bars.
CSTritt 8:8a2d07e4a8c3 65 }
CSTritt 8:8a2d07e4a8c3 66 }
CSTritt 8:8a2d07e4a8c3 67
CSTritt 8:8a2d07e4a8c3 68 if (active) { // Deal with active low vs. active high.
CSTritt 8:8a2d07e4a8c3 69 theBar = output;
CSTritt 8:8a2d07e4a8c3 70 } else {
CSTritt 8:8a2d07e4a8c3 71 theBar = ~output; // Invert bits for active low.
CSTritt 8:8a2d07e4a8c3 72 }
CSTritt 8:8a2d07e4a8c3 73 return 0; //
CSTritt 8:8a2d07e4a8c3 74 }