/*
 * EXAMPLE FIRMWARE FOR THE LARGE 7-SEGMENT DISPLAY
 * driver IC: STP16C26
 * author: martin@embedblog.eu
 * see the listing at https://www.tindie.com/products/edit/dual-large-7-segment-display-w-cc-driver/
 * Arduino-compatible example (modify the defines on top to suit your device - this waas written for STM32 BluePill, but should work on any Arduino board)
 * Connect power either via the IDC 6-pin, 8-pin header or the DC jack (all the 12 V pins are connected together!)
 * Send data either via the IDC-pin or the 8-pin header
 */

#define CLK_PIN       PB8
#define DIN_PIN       PB5
#define LAT_PIN       PB6
#define OE_PIN        PB7   //if you are not using the OE pin for dimming, tie it to ground

#define DIGITS        2     //how many digits are to be displayed (ie number of boards times 2)
char buffer[DIGITS];
byte decimal_point = 1;     //position of the decimal point (from left)

//this function provides simple translation between ASCII chars and data for the display
byte translate_ascii(char c)
{
  switch (c)
  {
    case '0': return 0b11111100;
    case '1': return 0b01100000;
    case '2': return 0b11011010;
    case '3': return 0b11110010;
    case '4': return 0b01100110;
    case '5': return 0b10110110;
    case '6': return 0b10111110;
    case '7': return 0b11100000;
    case '8': return 0b11111110;
    case '9': return 0b11110110;
    default: return 0b00000010;
  }
}

void setup() {
  //setup GPIO as outputs
  pinMode(PC13, OUTPUT);
  pinMode(CLK_PIN, OUTPUT);
  pinMode(DIN_PIN, OUTPUT);
  pinMode(LAT_PIN, OUTPUT);
  pinMode(OE_PIN, OUTPUT);
  analogWrite(OE_PIN, 0);

  //fill the buffer with chars we want to display
  buffer[0] = '8';
  buffer[1] = '1';

  //this part actually sends out the data
  for (byte i = 0; i < DIGITS; i++)
    shiftOut(DIN_PIN, CLK_PIN, LSBFIRST, translate_ascii(buffer[i]) | ((decimal_point - 1) == i ? 0b1 : 0b0));
  digitalWrite(LAT_PIN, HIGH);
  digitalWrite(LAT_PIN, LOW);
}

void loop() {}

/*
  in case you don't have the shiftOut function:
void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
{
  uint8_t i;

  for (i = 0; i < 8; i++)  
  {
    if (bitOrder == LSBFIRST)
      digitalWrite(dataPin, !!(val & (1 << i)));
    else      
      digitalWrite(dataPin, !!(val & (1 << (7 - i))));
                 
    digitalWrite(clockPin, HIGH);
    digitalWrite(clockPin, LOW);            
  }
}

*/