MAX7219_ LED_7segm_8digits

MAX7219_ LED_7segm_8digits.cpp

#include "Arduino.h"

void display_start();
void DisplayText(char *text);

void setup() {
    Serial.begin(115200);
    display_start();
    DisplayText("01234567");
}

void loop() {}

//****************************************************************************************************************************************************
//                         7 S E G M E N T   8 D I G I T S  MAX7219   D I S P L A Y *
//****************************************************************************************************************************************************

#define MAX_CS  21
#define MAX_DIN 22
#define MAX_CLK 17

#define SHUTDOWN_ADDR    12
#define DISPLAYTEST_ADDR 15
#define SCANLIMIT_ADDR   11
#define DECODEMODE_ADDR  9
#define BRIGHTNESS_ADDR  10

const byte ARRAY_SIZE = 23;
byte       segment_codes[ARRAY_SIZE];
String     available_chars[ARRAY_SIZE];

int indexOf(const char *base, char ch, int startIndex);

int findIndexOfChar(char character) {
    char s[24] = {"0123456789abcdefHLPS-_ "};
    int  p = indexOf(s, character, 0);
    if(p == -1) p = 22;
    return p;
}

void MAX7219_Write(volatile byte opcode, volatile byte data) {
    digitalWrite(MAX_CS, LOW);
    shiftOut(MAX_DIN, MAX_CLK, MSBFIRST, opcode);
    shiftOut(MAX_DIN, MAX_CLK, MSBFIRST, data);
    digitalWrite(MAX_CS, HIGH);
}

void _clear() {
    for(int i = 1; i <= 8; i++) { MAX7219_Write(i, segment_codes[21]); }
}

void DisplayText(char *text) {
    _clear();
    int s = strlen(text);
    for(int i = 0; i < 8; i++) {
        if(s < i) break;
        int p = findIndexOfChar(text[i]);
        MAX7219_Write(s - i, segment_codes[p]);
    }
}

int indexOf(const char *base, char ch, int startIndex = 0) {
    const char *p = base;
    for(; startIndex > 0; startIndex--)
        if(*p++ == '\0') return -1;
    char *pos = strchr(p, ch);
    if(pos == nullptr) return -1;
    return pos - base;
}

void display_start() {
    segment_codes[0] = 0b1111110;   // 0
    segment_codes[1] = 0b0110000;   // 1
    segment_codes[2] = 0b1101101;   // 2
    segment_codes[3] = 0b1111001;   // 3
    segment_codes[4] = 0b0110011;   // 4
    segment_codes[5] = 0b1011011;   // 5
    segment_codes[6] = 0b1011111;   // 6
    segment_codes[7] = 0b1110000;   // 7
    segment_codes[8] = 0b1111111;   // 8
    segment_codes[9] = 0b1111011;   // 9
    segment_codes[10] = 0b1110111;  // a
    segment_codes[11] = 0b0011111;  // b
    segment_codes[12] = 0b0001101;  // c
    segment_codes[13] = 0b0111101;  // d
    segment_codes[14] = 0b1001111;  // e
    segment_codes[15] = 0b1000111;  // f
    segment_codes[16] = 0b0110111;  // H
    segment_codes[17] = 0b0001110;  // L
    segment_codes[18] = 0b1100111;  // P
    segment_codes[19] = 0b0000001;  // -
    segment_codes[20] = 0b0001000;  // _
    segment_codes[21] = 0b0000000;  // space
    segment_codes[22] = 0b1001001;  // unknown

    pinMode(MAX_DIN, OUTPUT);
    pinMode(MAX_CS, OUTPUT);
    pinMode(MAX_CLK, OUTPUT);

    MAX7219_Write(DISPLAYTEST_ADDR, 0);
    MAX7219_Write(SCANLIMIT_ADDR, 8 - 1);
    MAX7219_Write(DECODEMODE_ADDR, 0);
    MAX7219_Write(BRIGHTNESS_ADDR, 4);  // 0 ... 15
    MAX7219_Write(SHUTDOWN_ADDR, 0x01);
    _clear();
}