This is just some test thing for the Arduino multi-function shield or as it funnily is spelled on the board "Mulie-function shidle" where it parses numbers in CSV lines and turns on the 7 segment display and LEDs plus some debouncing that does not work that well

mulie-shidle.cpp

#define BUZ 3
#define KNB A0
#define BT1 A1
#define BT2 A2
#define BT3 A3
#define LD1 10
#define LD2 11
#define LD3 12
#define LD4 13
#define DAT 8
#define CLK 7
#define LAT 4

uint8_t bpn[] = { BT1, BT2, BT3 }, bps[sizeof(bpn)] = { 0 }, hasval = 0, glyphs[4] = { 0 }, glpos = 0;
uint16_t everysectime = 0, lastaread = 0, last7seg = 0, lastup = 0, rval = 0, rpos = 0, dev = 0, lastanalog = 9999, thenum = 0;

void setup() {
  pinMode(KNB, INPUT);
  pinMode(BT1, INPUT_PULLUP);
  pinMode(BT2, INPUT_PULLUP);
  pinMode(BT3, INPUT_PULLUP);
  pinMode(LAT, OUTPUT);
  pinMode(CLK, OUTPUT);
  pinMode(DAT, OUTPUT);
  pinMode(BUZ, OUTPUT);
  pinMode(LD1, OUTPUT);
  pinMode(LD2, OUTPUT);
  pinMode(LD3, OUTPUT);
  pinMode(LD4, OUTPUT);
  Serial.begin(9600);
  digitalWrite(BUZ, LOW);
  delay(10);
  digitalWrite(BUZ, HIGH);
  setLeds(0);
  sendShift(0);
}

void loop() {
  readButtons();
  readAnalogs();
  checkTimers();
  readSerial();
  emit7Seg();
}

void onValue(uint16_t pos, uint16_t val, uint8_t end) {
  if (pos == 0 && !end) {
    dev = val;
  }

  if (pos == 1 || (end && pos == 0)) {
    useDevice(dev, val);
  }
}

void checkTimers() {
  uint16_t cur = millis();
  if (abs(cur - everysectime) >= 1000) {
    everysectime = cur;
    everySecond();
  }
}

void setLeds(uint8_t n) {
  digitalWrite(LD1, !(n & 1));
  digitalWrite(LD2, !((n >> 1) & 1));
  digitalWrite(LD3, !((n >> 2) & 1));
  digitalWrite(LD4, !((n >> 3) & 1));
}

void readAnalogs() {
  uint16_t now = millis();
  if (abs(now - lastaread) < 100) return;
  lastaread = now;
  int16_t read = analogRead(KNB);
  if (abs(read - lastanalog) >= 3) {
    lastanalog = read;
    Serial.print("3,");
    Serial.print(read);
    Serial.print(",");
    Serial.println(now);
  }
}

void readSerial() {
  int16_t read = Serial.read();
  if (read == -1) {
    return;
  } else if (read == ',') {
    endField(false);
    rpos++;
  } else if (read == '\n') {
    endField(true);
    rpos = 0;
  } else if (read >= '0' && read <= '9') {
    if (!hasval) {
      hasval = 1;
    }
    rval *= 10;
    rval += read - '0';
  }
}

void endField(uint8_t end) {
  if (!hasval) return;
  onValue(rpos, rval, end);
  hasval = 0, rval = 0;
}

void readButtons() {
  uint16_t now = millis();
  for (uint8_t i = 0; i < sizeof(bpn); i++) {
    bool down = !digitalRead(bpn[i]);
    if (bps[i] != down) {
      if (!down && abs(now - lastup) < 20) {
        return;
      }
      lastup = now;
      bps[i] = down;
      onButton(i, down);
    }
  }
}

void onButton(uint8_t butto, uint8_t state) {
  Serial.print(butto);
  Serial.print(",");
  Serial.print(state);
  Serial.print(",");
  Serial.println(millis());
  /*if (state == 1) {
    if (butto == 2) {
      thenum++;
    } else if (butto == 1) {
      thenum += 10;
    } else if (butto == 0) {
      thenum += 100;
      //glyphs[0] = glyphs[1] = glyphs[2] = glyphs[3] = 0;
      //sendShift(0);
    }
    if (thenum > 9999) thenum = 0;
    set7SegNum(thenum);
  }*/
}

void sendShift(uint16_t i) {
  digitalWrite(LAT, LOW);
  shiftOut(DAT, CLK, LSBFIRST, (i >> 8) & 255);
  shiftOut(DAT, CLK, LSBFIRST, i & 255);
  digitalWrite(LAT, HIGH);
}

void emit7Seg() {
  if (glyphs[0] == 0 && glyphs[1] == 0 && glyphs[2] == 0 && glyphs[3] == 0) return;
  uint16_t now = millis();
  if (abs(now - last7seg) < 5) return;
  last7seg = now;
  glpos = (glpos + 1) % 4;
  uint16_t out = 0;
  out |= ((~glyphs[glpos]) << 8);
  out |= 128 >> glpos;
  sendShift(out);
}

void set7SegNum(uint16_t num) {
  thenum = num;
  if (num > 9999) {
    glyphs[0] = 0;
    glyphs[1] = 0;
    glyphs[2] = 0;
    glyphs[3] = 0;
    return;
  }
  int16_t thousands = num / 1000;
  if (thousands) {
    glyphs[0] = numToGlyph(thousands);
  } else {
    glyphs[0] = 0;
  }
  num = num - (thousands * 1000);
  int hundreds = num / 100;
  if (hundreds || thousands) {
    glyphs[1] = numToGlyph(hundreds);
  } else {
    glyphs[1] = 0;
  }
  num = num - (hundreds * 100);
  int tens = num / 10;
  if (tens || hundreds || thousands) {
    glyphs[2] = numToGlyph(tens);
  } else {
    glyphs[2] = 0;
  }
  num = num - (tens * 10);
  glyphs[3] = numToGlyph(num);
}

uint8_t numToGlyph(uint8_t i) {
  switch (i) {
    case 0:
      return B11111100;
    case 1:
      return B01100000;
    case 2:
      return B11011010;
    case 3:
      return B11110010;
    case 4:
      return B01100110;
    case 5:
      return B10110110;
    case 6:
      return B10111110;
    case 7:
      return B11100000;
    case 8:
      return B11111110;
    case 9:
      return B11110110;
    default:
      return 0;
  }
}

void everySecond() {
  uint16_t n = random();
}

void useDevice(uint16_t dev, uint16_t val) {
  Serial.print("dev=");
  Serial.print(dev);
  Serial.print(" val=");
  Serial.println(val);

  if (dev == 0) {
    set7SegNum(val);
  } else if (dev == 1) {
    setLeds(val);
  }
}