Large 2.3" 7 segment display module with SPI interface

1// DM134B test program using hardware SPI (or ShiftOut)
2// This displays a seconds counter that counts from 0-999 seconds then resets.
3// If you added a button and relevant code you could use this as a stopwatch.
4// SoftPWM library used to avoid conflicts with timers and SPI when using hardware PWM
5// the SoftPWM library allows the display brightness to be adjusted in software.
6// This circuit will draw approx 600mA at full brightness displaying 8888 (21.5mA per segment) 
7// If high brightness not required either back off using onboard brightness pot or set to max 4 
8// brightness if using software control to adjust brightness through PWM. This will reduce power useage.
9// For example if using for a clock you could automatically dim the display at night.
10
11// 7-segment digits 0-9
12// {Q0, Q1, Q2, Q3, Q4, Q5, Q6, Q7} --> {g, f, e, d, c, b, a, DP} 
13
14#include <SPI.h>
15#include <SoftPWM.h>
16
17int dm134_clock = 13;
18int dm134_latch = 10; // DM134B datasheet says active low but seems to be active high (like a '595)?
19int dm134_data = 11;
20int dm134_OE = 9; // output enable; Active LOW. Can be used to control brightness with PWM.
21
22int brightness = 5; // set display brightness. 1-5 
23int brt = 0; // value for storing reversed PWM percentage
24
25long int cnt = 0; // counter initial value = 0
26unsigned long previousMillis = 0; 
27const long interval = 10;
28
29unsigned char Data[] = {0x7e,0x30,0x6d,0x79,0x33,0x5b,0x5f,0x70,0x7f,0x7b}; // array without decimal point in hex
30
31byte ssddigits[10] = // array without decimal points on
32{
33  B01111110,  // 0
34  B00001100,  // 1
35  B10110110,  // 2
36  B10011110,  // 3
37  B11001100,  // 4
38  B11011010,  // 5
39  B11111010,  // 6
40  B01001110,  // 7
41  B11111110,  // 8
42  B11011110,  // 9
43};
44
45byte ssddigitsDP[10] = // array with decimal points on
46{
47  B01111111,  // 0
48  B00001101,  // 1
49  B10110111,  // 2
50  B10011111,  // 3
51  B11001101,  // 4
52  B11011011,  // 5
53  B11111011,  // 6
54  B01001111,  // 7
55  B11111111,  // 8
56  B11011111,  // 9
57};
58
59void setup() 
60{
61  
62  pinMode (dm134_clock, OUTPUT);
63  pinMode (dm134_latch, OUTPUT);
64  pinMode (dm134_data, OUTPUT);
65  pinMode (dm134_OE,OUTPUT);
66  digitalWrite(dm134_OE,LOW); // enable output of DM134B.
67  setBrt();
68  SoftPWMBegin();
69  SoftPWMSet(9, 0); // init software PWM on pin 9. This pulses the DM134 OE pin on and off to control brightness.
70  SoftPWMSetPercent(9, brt);
71  
72}
73
74void setBrt() // this changes the DM134 brightness logarithmic reversed scale to a more linear one
75
76{
77  if (brightness == 1)
78  brt = 90;
79
80  else if (brightness == 2)
81  brt = 75;
82
83  else if (brightness == 3)
84  brt = 50;
85
86  else if (brightness == 4)
87  brt = 30;
88
89  else if (brightness == 5)
90  brt = 0;
91}
92
93void loop() 
94{
95   unsigned long currentMillis = millis();
96
97  if (currentMillis - previousMillis >= interval) 
98  {
99    previousMillis = currentMillis;
100    cnt++;   
101  }
102   
103   if (cnt == 999999)
104   {
105     cnt = 0;
106   }
107
108   
109   
110   displayNum();
111}
112
113void displayNum()
114{
115
116//long int num = analogRead(0);
117//long int num = 1234;
118long int num = cnt;
119
120// get digit 0
121int dig5 = num % 10; // ones
122// get digit 1
123int dig4 = (num / 10) % 10; // tens
124// get digit 2
125int dig3 = (num / 100) % 10; // hundreds
126// get digit 3
127int dig2 = (num / 1000) % 10; // thousands
128// get digit 4
129int dig1 = (num / 10000) % 10; // tenthousands
130// get digit 5
131int dig0 = (num / 100000) % 10; // hundredthousands
132
133SPI.beginTransaction(SPISettings(8000000, LSBFIRST, SPI_MODE0)); //reverse digits if left to right
134digitalWrite(dm134_latch,LOW);
135SPI.transfer(ssddigits[dig0]); 
136SPI.transfer(ssddigitsDP[dig1]);
137SPI.transfer(ssddigits[dig2]); 
138SPI.transfer(ssddigitsDP[dig3]);
139SPI.transfer(ssddigits[dig4]);
140SPI.transfer(ssddigits[dig5]);
141digitalWrite(dm134_latch,HIGH);
142SPI.endTransaction();
143
144/*
145// shift out digits
146digitalWrite(dm134_latch,LOW);
147shiftOut(dm134_data, dm134_clock, LSBFIRST, ssddigits[dig3]); 
148shiftOut(dm134_data, dm134_clock, LSBFIRST, ssddigits[dig2]); 
149shiftOut(dm134_data, dm134_clock, LSBFIRST, ssddigitsDP[dig1]);
150shiftOut(dm134_data, dm134_clock, LSBFIRST, ssddigits[dig0]);
151//shiftOut(dm134_data, dm134_clock, LSBFIRST, B00000001); // DP test
152//shiftOut(dm134_data, dm134_clock, LSBFIRST, B00000001); // DP test
153digitalWrite(dm134_latch,HIGH); 
154
155*/
156
157}