// A2) STM8 -> WS2812B (STM8S208, 25MHz Xtal)
// test driver for WS2812B using SPI (MOSI used as data ouput on PC6, SCK left unconnected, MISO free)
// variant with 2bits in 1 SPI byte

#include "stm8s.h"
#include "milis.h"

void init_spi(void);
void test(uint8_t* data, uint16_t delka);

// test pattern for (12 RGB LED ring)
uint8_t colors[36]={
0xff,0x00,0x00, // B
0x00,0xff,0x00, // R
0x00,0x00,0xff, // G
0x00,0x00,0x00, // black
0x2f,0x2f,0x2f  // light white
};

#define L_PATTERN 0b0100 // 333ns pulse, 999ns space
#define H_PATTERN 0b0110 // 666ns pulse, 666ns space

void main(void){
CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1);
CLK_ClockSwitchConfig(CLK_SWITCHMODE_AUTO, CLK_SOURCE_HSE, DISABLE, CLK_CURRENTCLOCKSTATE_ENABLE); // 24MHz Xtal oscillator
init_milis(); // millis using TIM4 - not necessary
init_spi();

 while (1){
  test(colors,sizeof(colors)); 	// transfer image into RGB LED string
  delay_ms(2);  								// wait some time
 }
}

// takes array of LED_number * 3 bytes (RGB per LED)
void test(uint8_t* data, uint16_t length){
 uint8_t mask,tmp;
 disableInterrupts(); // can be omitted if interrupts do not take more then about ~25us
 while(length){   // for all bytes from input array
  length--;
  mask=0b10000000; // for all bits in byte
  tmp=0; // combine two bit patterns into one byte there
  while(mask){
   if(mask & data[length]){ // set high nibble with corresponding bit pattern
    tmp |= H_PATTERN<<4;
   }else{
    tmp |= L_PATTERN<<4;
   }
   mask = mask >> 1;
   if(mask & data[length]){ // set low nibble with corresponding bit pattern
    tmp |= H_PATTERN;
   }else{
    tmp |= L_PATTERN;
   }
   mask = mask >> 1;
   while(!(SPI->SR & SPI_SR_TXE)); // wait for empty SPI buffer
   SPI->DR = tmp; // send pattern with two pulses / two bits for WS2812
  }
 }
 enableInterrupts();
while(SPI->SR & SPI_SR_BSY); // wait until end of transfer - now should come latch/reset (>50us in Low)
}

void init_spi(void){
// Software slave managment (disable CS/SS input), BiDirectional-Mode release MISO pin to general purpose
SPI->CR2 |= SPI_CR2_SSM | SPI_CR2_SSI | SPI_CR2_BDM | SPI_CR2_BDOE; 
SPI->CR1 |= SPI_CR1_SPE | SPI_CR1_MSTR | 2<<3; // Enable SPI as master at maximum speed (F_MCU/8, 24/2=3MHz)
}