ATtiny102/104 WS2812 Led Driver

[Stefan A. (ripper121)]

Guten Morgen,
ich habe hier ein kleinen Led Driver für bis zu 10 WS2812b Led's 
geschrieben. Das war für uns billiger als 6 RGB Leds über ein 18 Kanal 
PWM controller zu steuern.

/*  ATTINY104_LED_DRIVER
*  Created: 07/07/2016 08:20:00 PM
*  Author : Ripper121
*  Drive up to 10 WS2812b Led's over Uart
*  Protocol: 1 Start Byte (0x01), (Led count * 3) Color Bytes, 1 CRC Byte
*  ACK = 0xFF, NAK = 0x00
*  FOSC=1000000 :"After powering up the device or after a reset the system clock is automatically
*  set to calibrated internal 8MHz oscillator, divided by 8" (Datasheet pag.32)
*   But we need at least 8MHz so we set the divider to 1
          __________
      VCC--|1       14|--GND (TPI CLK)
      PA0--|2       13|--PB3 (CDC TX) -->USART_Transmit()
(TPI DATA)  PA1--|3       12|--PB2 (CDC RX) <--USART_Receive()
(RESET)    PA2--|4       11|--PB1 (BUTTON)
      PA3--|5       10|--PB0
      PA4--|6        9|--PA7
(LED)    PA5--|7        8|--PA6
         \__________/
Atmel ATtiny104/102 Xplained Nano
*/
#include <util/delay.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/interrupt.h>
#include "ws2812.h"
#define LED_PIN    (1 << PA5)
#define BUTTON_PIN (1 << PB1)

unsigned char packCRC(unsigned char *s, unsigned char length)
{
  unsigned char c = 0;
  for (unsigned char i = 0; i < length; i++) {
    c ^= s[i];
  }
  return c;
}

void USART_Transmit( unsigned char data )
{
  /* Wait for empty transmit buffer */
  while ( !( UCSRA & (1<<UDRE)) );
  /* Put data into buffer, sends the data */
  UDR = data;
}

unsigned char USART_Receive( void )
{
  /* Wait for data to be received */
  while ( !(UCSRA & (1<<RXC)) );
  /* Get and return received data from buffer */
  return UDR;
}

void USART_Flush( void )
{
  unsigned char dummy;
  while ( UCSRA & (1<<RXC) ) dummy = UDR;
}

/*----------------------------------------------------------------------------------------------------------------------------------------------------------*/
#define LEDPIX 6 //<- Max is 10
#define MAXPIX LEDPIX*3

int main(void){
  CCP = 0xD8; //Set Unsecure
  CLKPSR = 0; //Clockdiv 0 -> 8Mhz
  PUEB |= BUTTON_PIN;         // Enable Pull-Up function in PB1.
  PORTB |= BUTTON_PIN;        // Set Pull-Up for the Button.
  DDRA |= LED_PIN;            // Configure LED pin as Output.
  /*Set baud rate */
  UBRRH = (unsigned char)(51>>8);//9600 Baud @ 8Mhz
  UBRRL = (unsigned char)51;//9600 Baud @ 8Mhz
  /*Enable receiver and transmitter */
  UCSRB = (1<<RXEN)|(1<<TXEN);
  /* Set frame format: 8data, 2stop bit */
  UCSRC = (1<<USBS)|(3<<UCSZ0);
  _delay_ms(250);
  PORTA |= LED_PIN;         // Switch off the LED.
  
  while(1){
    unsigned char rxLedPack[MAXPIX],crcRGB = 0x00,rxcrcRGB = 0x00;
    if(UCSRA & (1<<RXC)){
      if(USART_Receive()==0x01){
        for(unsigned char i=0;i<MAXPIX;i++){
          rxLedPack[i]=USART_Receive();
        }
        crcRGB = packCRC(rxLedPack,MAXPIX);
        rxcrcRGB = USART_Receive();
        USART_Flush();
        if(rxcrcRGB==crcRGB){
          ws2812_sendarray((unsigned char *)rxLedPack,MAXPIX);
          USART_Transmit(0xFF);
        }
        else
        {
          for(unsigned char i=0;i<MAXPIX;i++){
            rxLedPack[i]=0x00;
          }
          ws2812_sendarray((unsigned char *)rxLedPack,MAXPIX);
          USART_Transmit(0x00);
        }
      }
    }
  }
}