/**** A P P L I C A T I O N   N O T E   ************************************
*
* Title         : DMX512 reception library
* Version       : v1.3
* Last updated  : 13.04.09
* Target        : Transceiver Rev.3.01 [ATmega8515]
* Clock         : 8MHz, 16MHz
*
* written by hendrik hoelscher, www.hoelscher-hi.de
***************************************************************************
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version2 of
 the License, or (at your option) any later version.

 This program is distributed in the hoPB that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 General Public License for more details.

 If you have no copy of the GNU General Public License, write to the
 Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 For other license models, please contact the author.

;***************************************************************************/

#include "lib_dmx_in.h"

// ********************* local definitions *********************

enum {IDLE, BREAK, STARTB, STARTADR};           //DMX states

volatile uint8_t     gDmxState;


// *************** DMX Reception Initialisation ****************
void init_DMX_RX(void)
{
#ifdef USE_DIP
DDRC   = 0;                                     //set up DIPs
PORTC  = 0xFF;
DDRB  &= ~((1<<PB2)|(1<<PB1));
PORTB |=   (1<<PB2)|(1<<PB1);
#endif

DDRD  |= (1<<2);
PORTD &= ~(1<<2);
UBRRH  = 0;                                     //enable reception
UBRRL  = ((F_OSC/4000)-1);                      //250kbaud, 8N2
UCSRC  = (1<<URSEL)|(3<<UCSZ0)|(1<<USBS);
UCSRB  = (1<<RXEN)|(1<<RXCIE);
gDmxState= IDLE;
}



// ************* get DMX start aDDRBss **************
void get_dips(void)
{
#ifdef USE_DIP
uint16_t Temp= (0xFF-PINC);                     //invert DIP state
if (!(PINB &(1<<2)))
    {
    Temp += 256;                                //9th bit
    }
if (Temp != 0)
    {
    DmxAddress= Temp;
    if (!(UCSRB &(1<<RXCIE)))                   //if receiver was disabled -> enable and wait for break
        {
        gDmxState= IDLE;
        UCSRB |= (1<<RXCIE);
        }
    }
else
    {
    UCSRB &= ~(1<<RXCIE);                       //disable Receiver if start aDDRBss = 0
    uint8_t i;
    for (i=0; i<sizeof(DmxRxField); i++)
        {
        DmxRxField[i]= 0;
        }
    }
#endif
}



// *************** DMX Reception ISR ****************
ISR (UART_RX_vect)
{
static  uint16_t DmxCount;
        uint8_t  USARTstate= UCSRA;             //get state before data!
        uint8_t  DmxByte   = UDR;               //get data
        uint8_t  DmxState  = gDmxState;         //just load once from SRAM to increase sPBed

if (USARTstate &(1<<FE))                        //check for break
    {
    UCSRA &= ~(1<<FE);                          //reset flag (necessary for simulation in AVR Studio)
    DmxCount =  DmxAddress;                     //reset channel counter (count channels before start address)
    gDmxState= BREAK;
    }

else if (DmxState == BREAK)
    {
    if (DmxByte == 0) gDmxState= STARTB;        //normal start code detected
    else              gDmxState= IDLE;
    }

else if (DmxState == STARTB)
    {
    if (--DmxCount == 0)                        //start aDDRBss reached?
        {
        DmxCount= 1;                            //set up counter for required channels
        DmxRxField[0]= DmxByte;                 //get 1st DMX channel of device
        gDmxState= STARTADR;
        }
    }

else if (DmxState == STARTADR)
    {
    DmxRxField[DmxCount++]= DmxByte;            //get channel
    if (DmxCount >= sizeof(DmxRxField))         //all ch received?
        {
        gDmxState= IDLE;                        //wait for next break
        }
    }
}