Method writeRegister

PxMatrix.h:421–479

}
#else
inline void PxMATRIX::writeRegister(uint16_t reg_value, uint8_t reg_position)
{
  if (_driver_chip == FM6124 || _driver_chip == FM6126A){

    if (_driver_chip == FM6124) {
       Serial.println("\nFM6124 - REG: " + String(reg_position));
    } else {
       Serial.println("\nFM6126A - REG: " + String(reg_position));
    }

    // All FM6126A code is based on the excellent guesswork by shades66 in https://github.com/hzeller/rpi-rgb-led-matrix/issues/746
    // Register 12 - brightness/gain settings, three 6bit values, aaaaaabbbbbbcccccc a= darkness?
    //               seems to add red to the background when the leds are off, b=main brightness c=finer brightness
    //               (i'm not sure if b & c are actually as 12 bit value but with b set to all 1's the value in c doesn't seem to make much difference)

    // Register 13 - not sure what it's doing yet, just that 1 specific bit within seems to be an overall enable function.

    // Now set all the values at the top to the same value for each of register 12/13 to get the same settings across the panel, the current code loads different settings into each 32 columns.
    // clocking in the register is simply clocking in the value (i've 2 panels so 128bits of data) and for the last 12/13 bits depending on the register setting the latch to high. the final drop of latch to low clocks in the configuration. this is done by sending the same value to r1/r2/g1/g2/b1/b2 at the same time to load the config into all the FM6126 chips

    // Some necessary magic bit fields
    // b12  - 1  adds red tinge
    // b12  - 9/8/7/6/5  =  4 bit brightness
    // b13  - 9   =1 screen on
    // b13  - 6   =1 screen off
    pinMode(_SPI_CLK,OUTPUT);
    pinMode(_SPI_MOSI,OUTPUT);
    digitalWrite(_SPI_CLK,HIGH); // CCK LOW
    digitalWrite(_OE_PIN,LOW);
    digitalWrite(_LATCH_PIN,HIGH);
    digitalWrite(_A_PIN,HIGH);
    digitalWrite(_B_PIN,LOW);
    digitalWrite(_C_PIN,LOW);
    digitalWrite(_D_PIN,LOW);

    uint8_t reg_bit=0;
    for (uint32_t bit_counter=0; bit_counter < _send_buffer_size*8; bit_counter++)
    {
      reg_bit=bit_counter%16;
      if ((reg_value>>reg_bit)&1)
        digitalWrite(_SPI_MOSI,HIGH);
      else
        digitalWrite(_SPI_MOSI,LOW);

      delay(1);
      digitalWrite(_SPI_CLK,LOW); // CLK HIGH
      delay(1);
      digitalWrite(_SPI_CLK,HIGH); // CLK LOW
      delay(1);
      if ((bit_counter ==  (_send_buffer_size*8 - reg_position-1)))
      {
        digitalWrite(_LATCH_PIN,LOW);
      }
    }
    digitalWrite(_LATCH_PIN,HIGH);
  }
  digitalWrite(_OE_PIN,HIGH);