Tim Johnson / Mbed 2 deprecated 7SegmentDisplay_float

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Dependencies:   mbed

Fork of 7SegmentDisplay by Svend Kaffke

main.cpp@2:3cf4eba9de56, 2016-09-04 (annotated)

Committer:
captaintim
Date:
Sun Sep 04 11:54:00 2016 +0000
Revision:
2:3cf4eba9de56
Parent:
1:46dbd77e0701
Child:
3:c747b832518f
displays decimal number to a 4 digit, 7segment display (LDQ-N514R1), reveal how to finesse digits out one at a time for display, and flash display fast enough to show decimal number

Who changed what in which revision?

UserRevisionLine numberNew contents of line
ShingyoujiPai 0:463ff11d33fa 1 #include "mbed.h"
ShingyoujiPai 0:463ff11d33fa 2
captaintim 1:46dbd77e0701 3 /*test program to learn how to write code for a 4 digit, 7-segment LED display LDQ-N524R1
captaintim 1:46dbd77e0701 4 The schematic for this (COMMON CATHODE) display shows the following connections
captaintim 1:46dbd77e0701 5 schematic located at http://www.lumex.com/ldq-n514ri (open Specs PDF for drawing)
captaintim 1:46dbd77e0701 6 The Common Cathode means that to turn on the segments of the 7-segment (including decimal point)
captaintim 1:46dbd77e0701 7 you write a one to that segment.
captaintim 1:46dbd77e0701 8 For this 4 digit display (LDQ-N524R1), each digit works backward--like its wired Common Anode so
captaintim 1:46dbd77e0701 9 You write a ZERO to turn on the selected digit AND a ONE to turn off the digit.
captaintim 1:46dbd77e0701 10
captaintim 1:46dbd77e0701 11 Pin Out wiring guide:(connect the display pin # to XX mbed pin)
ShingyoujiPai 0:463ff11d33fa 12
captaintim 1:46dbd77e0701 13 CONTROL DISPLAY Pin# MBED Pin#
captaintim 1:46dbd77e0701 14 ----------------------------------
captaintim 1:46dbd77e0701 15 Digit1 12 14
captaintim 1:46dbd77e0701 16 Digit2 9 13
captaintim 1:46dbd77e0701 17 Digit3 8 12
captaintim 1:46dbd77e0701 18 Digit4 6 11
captaintim 1:46dbd77e0701 19 DP 3 10
captaintim 1:46dbd77e0701 20 A 11 21
captaintim 1:46dbd77e0701 21 B 7 22
captaintim 1:46dbd77e0701 22 C 4 23
captaintim 1:46dbd77e0701 23 D 2 24
captaintim 1:46dbd77e0701 24 E 1 25
captaintim 1:46dbd77e0701 25 F 5 26
captaintim 1:46dbd77e0701 26 G 5 27
captaintim 1:46dbd77e0701 27
captaintim 1:46dbd77e0701 28 There is no blanking on this display,
captaintim 2:3cf4eba9de56 29 Program demonstrates writing to all four digits of the 7-segment LED display of the LDQ-N514R1 a decimal number
captaintim 2:3cf4eba9de56 30 Since the segments only light up for one selected digit, all 4 digit has to be flashed to show 4 separate numbers
captaintim 2:3cf4eba9de56 31 Television used this by flashing 30 screens per second call persistence enhanced cathode ray tubes.
ShingyoujiPai 0:463ff11d33fa 32
captaintim 1:46dbd77e0701 33 Author: Cap'n Tim Johnson PE
captaintim 1:46dbd77e0701 34 Retired Professor
captaintim 1:46dbd77e0701 35 Wentworth Institude of Technology
captaintim 1:46dbd77e0701 36 Dept. Electrical Engineering and Technology
captaintim 1:46dbd77e0701 37 Boston, MA
captaintim 1:46dbd77e0701 38 */
captaintim 1:46dbd77e0701 39
captaintim 1:46dbd77e0701 40 //Setup:
captaintim 1:46dbd77e0701 41 DigitalOut Digit1(p14); //construct to control digits
captaintim 1:46dbd77e0701 42 DigitalOut Digit2(p13);
captaintim 1:46dbd77e0701 43 DigitalOut Digit3(p12);
captaintim 1:46dbd77e0701 44 DigitalOut Digit4(p11);
captaintim 2:3cf4eba9de56 45 DigitalOut myled (LED1); //Signal used for runtime checking
captaintim 1:46dbd77e0701 46
captaintim 1:46dbd77e0701 47 //these are the pins associated with writing to the "led"
captaintim 1:46dbd77e0701 48 DigitalOut led[8]={p21, p22, p23, p24, p25, p26, p27, p10};
captaintim 1:46dbd77e0701 49
captaintim 1:46dbd77e0701 50 //segments are in alphabetical order a-g, followed by Decimal point in the array below
captaintim 1:46dbd77e0701 51
captaintim 1:46dbd77e0701 52 int matrix[11][8]={
captaintim 1:46dbd77e0701 53 {1,1,1,1,1,1,0,0}, //zero
captaintim 1:46dbd77e0701 54 {0,1,1,0,0,0,0,0}, //one
captaintim 1:46dbd77e0701 55 {1,1,0,1,1,0,1,0}, //two
captaintim 1:46dbd77e0701 56 {1,1,1,1,0,0,1,0}, //three
captaintim 1:46dbd77e0701 57 {0,1,1,0,0,1,1,0}, //four
captaintim 1:46dbd77e0701 58 {1,0,1,1,0,1,1,0}, //five
captaintim 1:46dbd77e0701 59 {1,0,1,1,1,1,1,0}, //six
captaintim 1:46dbd77e0701 60 {1,1,1,0,0,0,0,0}, //seven
ShingyoujiPai 0:463ff11d33fa 61 {1,1,1,1,1,1,1,0}, //eight
captaintim 1:46dbd77e0701 62 {1,1,1,0,0,1,1,0}, //nine
ShingyoujiPai 0:463ff11d33fa 63 {0,0,0,0,0,0,0,1} //dot
ShingyoujiPai 0:463ff11d33fa 64 };
ShingyoujiPai 0:463ff11d33fa 65
captaintim 2:3cf4eba9de56 66 //create matrix to handle decimal point
captaintim 2:3cf4eba9de56 67 int matrixdecimal[11][8]={
captaintim 2:3cf4eba9de56 68 {1,1,1,1,1,1,0,1}, //zero
captaintim 2:3cf4eba9de56 69 {0,1,1,0,0,0,0,1}, //one
captaintim 2:3cf4eba9de56 70 {1,1,0,1,1,0,1,1}, //two
captaintim 2:3cf4eba9de56 71 {1,1,1,1,0,0,1,1}, //three
captaintim 2:3cf4eba9de56 72 {0,1,1,0,0,1,1,1}, //four
captaintim 2:3cf4eba9de56 73 {1,0,1,1,0,1,1,1}, //five
captaintim 2:3cf4eba9de56 74 {1,0,1,1,1,1,1,1}, //six
captaintim 2:3cf4eba9de56 75 {1,1,1,0,0,0,0,1}, //seven
captaintim 2:3cf4eba9de56 76 {1,1,1,1,1,1,1,1}, //eight
captaintim 2:3cf4eba9de56 77 {1,1,1,0,0,1,1,1}, //nine
captaintim 2:3cf4eba9de56 78 {0,0,0,0,0,0,0,1} //dot...actually a leading null space
captaintim 2:3cf4eba9de56 79 };
ShingyoujiPai 0:463ff11d33fa 80
captaintim 2:3cf4eba9de56 81 //set persistance (wait value on digits or flash rate)
captaintim 2:3cf4eba9de56 82 float f = 0.005;
captaintim 2:3cf4eba9de56 83 //enter a float number here (with a decimal in it) starting point
captaintim 2:3cf4eba9de56 84 volatile float temp = 31.45;
captaintim 2:3cf4eba9de56 85
captaintim 2:3cf4eba9de56 86 int main(){
captaintim 2:3cf4eba9de56 87 //finessing the digits out one at a time knowing 2nd digit has the decimal
captaintim 2:3cf4eba9de56 88 int tempasinteger = temp * 100; //removes decimal and typecasts float to integer
captaintim 2:3cf4eba9de56 89 int temp1a=tempasinteger/1000; //typecast float to integer for 1st digit (was)
captaintim 2:3cf4eba9de56 90 int temp2 = tempasinteger - temp1a*1000; //gets last 3 digits
captaintim 2:3cf4eba9de56 91 int temp2a = temp2/100; //typecast float to integer for 2nd digit
captaintim 2:3cf4eba9de56 92 int temp3 = temp2 - temp2a*100; //get last 2 digits
captaintim 2:3cf4eba9de56 93
captaintim 2:3cf4eba9de56 94 int temp3a=temp3/10; //typecast float to integer for 3rd digit
captaintim 2:3cf4eba9de56 95 int temp4=temp3-temp3a*10; //gets last digit
captaintim 2:3cf4eba9de56 96 int temp4a = temp4; //convenient renaming for writing digit to display
captaintim 2:3cf4eba9de56 97
captaintim 2:3cf4eba9de56 98 //begin one write of the display by turning off all the digits
captaintim 1:46dbd77e0701 99 Digit1 = 1; //turn off digit1
captaintim 1:46dbd77e0701 100 Digit2 = 1; //turn off digit2
captaintim 1:46dbd77e0701 101 Digit3 = 1; //turn off digit3
captaintim 1:46dbd77e0701 102 Digit4 = 1; //turn off digit4
captaintim 2:3cf4eba9de56 103 while (1) {
captaintim 2:3cf4eba9de56 104 //turns off last led's segments values
captaintim 1:46dbd77e0701 105 for(int i = 0; i<8;i++){
captaintim 2:3cf4eba9de56 106 led[i] = 0;}
captaintim 2:3cf4eba9de56 107 //belows holds row of matrix and assign column value from matrix
captaintim 2:3cf4eba9de56 108 Digit1 = 0; //turns on digit1
captaintim 2:3cf4eba9de56 109 for (int i=0; i<8; i++){
captaintim 2:3cf4eba9de56 110 led[i] = matrix[temp1a][i];
captaintim 2:3cf4eba9de56 111 }
captaintim 2:3cf4eba9de56 112 wait(f);
captaintim 2:3cf4eba9de56 113 Digit1=1;
ShingyoujiPai 0:463ff11d33fa 114
captaintim 2:3cf4eba9de56 115 //turns off last led's segments values
captaintim 2:3cf4eba9de56 116 for(int i = 0; i<8;i++){
captaintim 2:3cf4eba9de56 117 led[i] = 0;}
captaintim 2:3cf4eba9de56 118 //belows holds row of matrix and assign column value from matrix
captaintim 2:3cf4eba9de56 119 Digit2 = 0; //turns on digit2 with decimal
captaintim 1:46dbd77e0701 120 for (int i=0; i<8; i++){
captaintim 2:3cf4eba9de56 121 //since we have prior knowledge of the decimal location
captaintim 2:3cf4eba9de56 122 //and this is a demonstration program, we add the decimal for this digit
captaintim 2:3cf4eba9de56 123 led[i] = matrixdecimal[temp2a][i];
captaintim 2:3cf4eba9de56 124 }
captaintim 2:3cf4eba9de56 125 wait(f);
captaintim 2:3cf4eba9de56 126 Digit2=1;
captaintim 2:3cf4eba9de56 127
captaintim 2:3cf4eba9de56 128 //turns off last led's segments values
captaintim 2:3cf4eba9de56 129 for(int i = 0; i<8;i++){
captaintim 2:3cf4eba9de56 130 led[i] = 0;}
captaintim 2:3cf4eba9de56 131 //belows holds row of matrix and assign column value from matrix
captaintim 2:3cf4eba9de56 132 Digit3 = 0; //turns on digit3
captaintim 2:3cf4eba9de56 133 for (int i=0; i<8; i++){
captaintim 2:3cf4eba9de56 134 led[i] = matrix[temp3a][i];
captaintim 2:3cf4eba9de56 135 }
captaintim 2:3cf4eba9de56 136 wait(f);
captaintim 2:3cf4eba9de56 137 Digit3=1;
captaintim 2:3cf4eba9de56 138
captaintim 2:3cf4eba9de56 139 //turns off last led's segments values
captaintim 2:3cf4eba9de56 140 for(int i = 0; i<8;i++){
captaintim 2:3cf4eba9de56 141 led[i] = 0;}
captaintim 2:3cf4eba9de56 142 //belows holds row of matrix and assign column value from matrix
captaintim 2:3cf4eba9de56 143 Digit4 = 0; //turns on digit4
captaintim 2:3cf4eba9de56 144 for (int i=0; i<8; i++){
captaintim 2:3cf4eba9de56 145 led[i] = matrix[temp4a][i]; }
captaintim 2:3cf4eba9de56 146 wait(f);
captaintim 2:3cf4eba9de56 147 Digit4=1;
captaintim 2:3cf4eba9de56 148
captaintim 2:3cf4eba9de56 149 }
ShingyoujiPai 0:463ff11d33fa 150 }