TTP229BSF WITH STM8S003F3

#define SCL_PIN PC4
#define SDO_PIN PC3
char keypad[16];
int key;
void setup()
{
  Serial_begin(38400);
  pinMode(SCL_PIN, OUTPUT);
  pinMode(SDO_PIN, INPUT);
  digitalWrite(SCL_PIN, HIGH);
  Serial_print_c('h');
  delay(1000);
}
void loop()
{
  readKeypad();
}
void readKeypad()
{
  WaitForTouch();
  for (int i = 0; i < 16; i++)
  {
    digitalWrite(SCL_PIN, LOW);
    delayMicroseconds(10);
    //Serial.print(digitalRead(SDO_PIN));
    keypad[i] = (1 - digitalRead(SDO_PIN)) + 0x30;
    //  Serial.print(keypad[i]);
    digitalWrite(SCL_PIN, HIGH);
    delayMicroseconds(10);
  }
  for (int i = 0; i < 16; i++)
  {
    if ( (keypad[i] - 0x30) == 1)
    {
      key = i;
      Serial_print_c(key / 10 + 0x30);
      Serial_print_c(key % 10 + 0x30);
      Serial_print_c(0XD);
      break;
    }
  }
  delay(200);
}
void WaitForTouch(void)
{
  while (digitalRead(SDO_PIN));
  while (!digitalRead(SDO_PIN));
  delayMicroseconds(10); // Tw
}